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A thorough understanding of SCERT Kerala Syllabus 10th Standard Biology Notes Pdf and Class 10 Biology Chapter 5 Immunity and Healthcare Notes Questions and Answers English Medium can improve academic performance.

SSLC Biology Chapter 5 Notes Questions and Answers Pdf Immunity and Healthcare

SCERT Class 10 Biology Chapter 5 Immunity and Healthcare Notes Pdf

SSLC Biology Chapter 5 Questions and Answers – Let Us Assess

Question 1.
From the sequence of activities related to phagocytosis, select the correct answer.
a) Expulsion of waste materials
b) Engulfment of pathogens in phagosome
c) Enzymes destroy the pathogen
d) Phagocyte approaches the pathogen
e) Phagolysosome is formed
i) d, c, e, b, a
ii) d, b, e, c, a
iii) b, c, e, a, d
iv) b, e, c, a, d
Answer:
ii) d, b, e, c, a

Question 2.
Find out those related to B lymphocytes from the following and choose the correct option.
a) Production of antibodies
b) Destruction of cancer cells
c) Maturation in the thymus gland
d) Formation in the bone marrow
i) a, b and d are correct
ii) a, c and d are correct
iii) b and c are correct
iv) a and d are correct
Answer:
iv) a and d are correct

Question 3.
Which of the following is the correct pair of phagocytes?
• Eosinophil, Neutrophil
• Basophil, Neutrophil
• Neutrophil, Monocyte
• Monocyte, Lymphocyte
Answer:
• Neutrophil, Monocyte

Question 4.
Analyse the given table and find the one in which both the statement and the reason are correct.

Answer:
ii. Blood clotting is a defence mechanism. –  Prevents the flow of blood as well as blocks the entry of pathogens when there is a wound.

Question 5.
From the following, select the statements that are correct, regarding vaccines:
• The immunity produced by vaccines is innate immunity.
• Vaccines help to produce antibodies against pathogens.
• All vaccines contain deactivated pathogens.
Answer:
Vaccines act as antigens. Vaccines help to produce antibodies against pathogens.

Question 6.
The following text is from a placard prepared in connection with World AIDS Day:
Change ourselves, Change the Perspectives
Evaluate the text on the placard based on the following indicators.
i) Social responsibility to stop the disease
ii) Approach toward those affected by the disease
Answer:
i) Social responsibility to stop the disease:
The spread of HTV is a social problem. Therefore, the community must come together to gain knowledge about preventive measures and implement them in life. Every citizen has the responsibility to disseminate correct information and correct misconceptions.

ii) Approach toward those affected by the disease: HIV is not transmitted by sharing food, touching, coughing, or shaking hands. Society needs to embrace this fact. It is a social duty to provide the necessary love, respect, and support to those affected by the disease. Only when discrimination is eliminated patients can seek treatment without fear and lead normal lives.

Question 7.
Analyse the table showing certain pathogens in an area and the number of people affected by them and answer the questions.

i) Which disease affected more people in the region?
ii) Which bacterial disease affected the people?
iii) Which pathogen affected the residents who bathed in stagnant fresh water?
iv) Prepare a note on the precautions to be taken to prevent vectors in the region.
Answer:
i) Malaria (Plasmodium)
ii) Leptospirosis (pathogen: Leptospira)
iii) Naegleria fowleri, Leptospira
iv) Precautions to be taken to prevent disease vectors:

• Completely avoid stagnant water around and inside the house (plant pots, refrigerator trays, tyres, gutters, broken containers).
• Keep wells, tanks, and other water reservoirs netted or closed.
• Clean the house and surroundings once a week and observe a Dry Day.
• Dispose household waste properly. Accumulation of waste attracts rats.

Question 8.
Give reasons.
Although antibiotics are effective medicines, their irrational use is harmful.
Answer:
The indiscriminate use of antibiotics increases the resistance of bacteria. When antibiotics are taken, they not only kill disease-causing bacteria, but also bacteria that are beneficial to the body (especially those in the digestive system).

Biology Class 10 Chapter 5 Notes Kerala Syllabus Immunity and Healthcare

Question 1.
In what ways do pathogens enter our bodies?
Answer:

1. Through the air
2. Through contaminated water or food
3. Through skin

Question 2.
Even though we live in the midst of pathogens, most of the time we don’t suffer from diseases. What would be the reason?
Answer:
Although germs are always around us, the main reason why most of us do not get sick all the time is because of our body’s very strong immune system. In addition, the amount and strength of germs, and a healthy lifestyle are also factors that influence this.

Question 3.
Analyse illustration 5.2 and complete Table 5.1.


Answer:

Answers to the indicators on page 140 of the textbook
Question 4.
Phagosome:
Answer:
Phagocytes (phagosome) are blood cells that engage in the process of phagocytosis.

Question 5.
Importance of the formation of phagolysosome:
Answer:
Inside the phagolysosome, powerful enzymes in the lysosome digest the pathogen and break it into pieces to destroy it. Phagolysosome formation is essential for inactivating pathogens such as bacteria, viruses, and fungi that have entered the body and breaking down their harmful components.

Question 6.
Phagocytosis – stages:
Answer:

• The phagocyte cell is attracted to the site of infection by chemicals released by the pathogen or by signals from damage to the body.
• The phagocyte cell uses its cell membrane to engulf the pathogen. This cavity inside the cell where the pathogen has entered is called the phagosome.
• The phagosome fuses with a lysosome. The resulting cavity is called the phagolysosome. This step is crucial for destroying the pathogen.
• Inside the phagolysosome, powerful digestive enzymes (for example, hydrolytic enzymes) in the lysosome digest the pathogen’s cell wall and proteins.
• After the pathogen is completely destroyed and digested, the unwanted debris is expelled from the cell.

Answers to the indicators on page 141 of the textbook
Question 7.
Histamine – Function:
Answer:
By dilating blood vessels and increasing their permeability, histamine helps to deliver immune cells and factors needed to destroy pathogens to the injured area as quickly as possible.

Question 8.
The advantage of the dilation of the capillary wall:
Answer:
The dilation of the capillary wall rapidly delivers
immune cells, plasma, and antibodies to the site of infection, increasing the body’s ability to destroy pathogens and repair damage.

Question 9.
Inflammatory response – an immune activity:
Answer:
The inflammatory response is a local immune response that occurs when the body is injured or invaded by pathogens. It is an emergency response that the body takes to destroy pathogens, repair damage, and heal. This response creates a barrier to pathogens, rapidly recruits phagocytes to the site of injury, and ultimately allows cells to destroy the pathogens and repair the damage.

Question 10.
Are neutrophils and monocytes the only types of phagocytes? Find out.
Answer:
Phagocytes are mainly divided into three types of cells:

• Neutrophils: These are the most abundant white blood cells. They are the first to arrive at the site of infection. They play a key role in the rapid response to disease.
• Macrophages: Macrophages are large cells that are transformed when monocytes leave the blood vessels and enter the tissues.
• Dendritic cells: These are found mainly in the skin, lungs, and digestive tract. They are capable of engulfing pathogens.

Question 11.
Why does the inflamed area become red and warm? Find out.
Answer:
The main reason for redness and increased heat in an inflamed area is increased blood flow to that area. Both of these symptoms (redness and heat) indicate the body’s attempt to quickly mobilize immune cells (phagocytes) to the site of infection.

Question 12.
Pyrogens – importance
Answer:
When the body temperature rises above the normal range, infection or inflammation occurs, and then the white blood cells release chemical substances called pyrogens. These trigger the brain to raise the body temperature.

Question 13.
The advantage of the rise in body temperature
Answer:
High temperature helps phagocytes to destroy pathogens more quickly by engulfing them, inhibits the growth of pathogens, and enhances immunity. This is a sign that the body is fighting against the disease. Once the infection is gone, the body temperature returns to the normal level.

Answers to the indicators on page 141 of the textbook
Question 14.
Factors that help in the clotting of blood:
Answer:
The enzyme thromboplastin, the protein prothrombin, thrombin, the inactive protein fibrinogen, and fibrin.

Question 15.
Processes involved in the clotting of blood:
Answer:

• When an injury occurs, the platelets and damaged tissues at the site produce an enzyme called thromboplastin. This converts a protein in the blood plasma called prothrombin into thrombin.
• Thrombin then converts an inactive protein called fibrinogen into fibrin.
• The fibrin forms a network of fibres that traps red blood cells, forming a blood clot.
• This clot prevents further blood loss until the wound is healed.

Question 16.
Clotting of blood – an immune activity:
Answer:
Blood clotting (Coagulation) is an integral part of the body’s immune system. It is the first line of defence that prevents pathogens from entering the body and controls blood loss.

Question 17.
To which category does the immunity received through antibodies from breast milk belongs? Find out.
Answer:
The immunity provided to the baby through antibodies through breast milk falls under the category of Natural Passive Immunity.

Question 18.
Analyse illustration 5.5 and appropriately complete table 5.2 containing information about lymphocytes.

Answer:

Question 19.
Analyse table 5.3 related to vaccines and gain understanding. Find out how vaccines are classified based on their components.

Answer:

Answers to the indicators on page 144 of the textbook
Question 20.
Vaccination:
Answer:
Vaccination is an important process that provides our body with immunity against diseases. It is a way to achieve Artificial Active Immunity.

Question 21.
Vaccines components:
Answer:

Question 22.
Types of vaccines:
Answer:
Vaccines are classified into several types based on the method used to make them. Each type of vaccine induces immunity in the body in a different way.

1. Live-Attenuated Vaccines
2. Inactivated Vaccines
3. Subunit / Toxoid Vaccines
4. mRNA Vaccines

Question 23.
The components of vaccines are pathogens or their parts. How do they impart immunity?
Answer:
Vaccines act as antigens in our body. It stimulates our immune system and helps to produce antibodies against pathogens. These antibodies remain in the body and provide long-term protection against diseases. By taking the doses accurately, vaccines help to gain protection from a disease for many years or even for a lifetime.

Question 24.
Are there vaccines which are taken by other means than by injection? Find out.
Answer:
Non-injectable vaccines are available in two main forms:

• Oral Vaccines: Oral Polio Vaccine (OPV).
• Nasal Spray Vaccines: Influenza (Flu) Vaccine

Question 25.
What can be done to strengthen the immune system in humans? Discuss.
Answer:

• Lifestyle adjustments (proper sleep, stress reduction, regular exercise, etc.)
• Healthy diet
• Disease prevention methods (vaccination, personal hygiene, avoiding drugs, etc.).

Question 26.
What are the ways to prevent the spread of diseases? Discuss.
Answer:

1. Personal hygiene
2. Environmental hygiene
3. Healthy habits

Answers to the indicators on page 149 of the textbook
Question 27.
Disease – pathogens:
Answer:
AIDS: Human Immunodeficiency Virus (HIV).

Question 28.
Mode of transmission:
Answer:
HIV can be transmitted through sexual contact with an infected person, by sharing needles and syringes that are not HIV-free, through transfusion of blood or organs containing HIV, and from an infected mother to the foetus.

Question 29.
Precautions to prevent the disease:
Answer:

• Use condoms and take preventive medications to prevent transmission through sexual intercourse.
• Do not use the same needle repeatedly to prevent transmission through blood.
• To prevent transmission from mother to child, HIV-infected mothers should avoid breastfeeding and give formula milk instead.
• Give medicines to the baby during pregnancy and childbirth, and continuously monitor the baby’s health after birth and provide necessary medicines.

Question 30.
People infected with COVID-19 lose their ability to taste and smell? Find out the reason.
Answer:
This is because this virus affects the nervous system and the cells in the respiratory tract.

Question 31.
Disease – pathogens:
Answer:
Nipah: Nipah virus

Question 32.
Mode of transmission:
Answer:

1. From bats to humans
2. From animals to humans
3. From humans to humans

Question 33.
Precautions to prevent the disease:
Answer:

1. Do not eat fruits that have been bitten or eaten by bats, especially dates and mangoes.
2. If you see symptoms (shortness of breath, cough, fever) in pigs or other domestic animals, avoid contact completely.
3. Wash your hands frequently with soap and water, especially after touching public places and before eating.
4. Avoid close contact with individuals with Nipah symptoms.

Answers to the indicators on page 152 of the textbook
Question 34.
Disease – pathogen:
Answer:
Malaria: Plasmodium

Question 35.
Mode of transmission:
Answer:
Female Anopheles mosquito transmits this pathogen from one person to another.

Question 36.
Precautions for the prevention of disease:
Answer:

1. Prevent mosquito bites
2. Prevent mosquito breeding
3. Prevention through medication

Answers to the indicators on page 153 of the textbook
Question 37.
Disease – pathogen:
Answer:
Filariasis: Filarial worm

Question 38.
Symptoms:
Answer:
Body parts such as legs, arms, and genital organs become excessively swollen and enlarged.

Question 39.
Prevention:
Answer:
Prevent mosquito breeding, dispose of waste, and install screens on windows and doors to prevent mosquitoes from entering the house.

Question 40.
The disease condition called cancer:
Answer:
Cancer is a condition in which abnormal and uncontrolled cell division leads to the multiplication of cells.

Question 41.
Reasons:
Answer:
Genetic changes, Environmental factors, Viral infections, Lifestyle

Question 42.
Peculiarity of cancer cells:
Answer:
Normal cells become cancerous when the control mechanisms in the cell division process are disrupted. Cancer cells divide uncontrollably.

Question 43.
Treatment methods:
Answer:
Surgery, Chemotherapy, Radiation therapy. Immunotherapy, Targeted therapy, Hormone therapy, etc. are the treatment methods.

Question 44.
There are also diseases that are not transmitted from one person to another. What are some such diseases that you know of? Collect information and complete Table 5.5.

Answer:

Question 45.
Haven’t you understood about various diseases? Based on this, complete illustration 5.12

Answer:

Question 46.
When should one seek treatment?
Answer:

1. When symptoms appear
2. As a precaution
3. Before and during pregnancy

Answers to the indicators on page 157 of the textbook
Question 47.
Medicines used in Ayurveda:
Answer:
In Ayurveda, plant and animal-based substances are used as medicines.

Question 48.
Treatment method in Homeopathy:
Answer:
This is a method of treatment that uses diluted doses of natural substances that cause symptoms in a healthy person to prevent disease.

Question 49.
Modern medicine:
Answer:
This system corrected superstitions related to diseases and gave importance to pathogens, diagnosis and the medicines.

Answers to the indicators on page 158 of the textbook
Question 50.
Stages of modern medical treatment:
Answer:

1. Assessing the symptoms
2. Laboratory test
3. Body check-up
4. Treatment (Medicine, Surgery, Organ transplantation, Radiation therapy).

Question 51.
Diagnostic measures:
Answer:

1. Assessing the symptoms
2. Laboratory test
3. Body check-up

Question 52.
Methods of treatment:
Answer:
Medicine, Surgery, Organ transplantation, Radiation therapy, etc. are the treatment methods.

Question 53.
Among the devices used for diagnosis, list those that you know.
Answer:
DIAGNOSTIC EQUIPMENT

1. Along with assessing the symptoms, diagnosis is also important.
2. Some examples of instruments used for diagnosis are:

a) Stethoscope
b) Sphygmomanometer
c) Digital BP apparatus
d) Pulse oximeter
e) Thermometer
f) Endoscope
g) US scanner, CT scanner, MRI scanner

Question 54.
Analyse the given collage in page 158 and complete table 5.6


Answer:

Question 55.
There are various specialisations to make treatment more effective.
Analyse the board displayed in the hospital, identify more departments and find out what each one is related to.
Answer:

• General Medicine – The medical speciality concerned with the diagnosis, treatment, and prevention of diseases that do not require surgery.
• Cardiology – The branch of medicine concerned with the study, diagnosis, and treatment of diseases that affect the heart and blood vessels.
• Paediatrics – The branch of science concerned with the health, diseases, and care of infants, children, and adolescents.
• Gynaecology – The branch of science concerned with the health problems, diseases, and treatment of the female reproductive system.
• Urology – The branch of science concerned with the diseases and surgeries that affect the urinary system of men and women, as well as the male reproductive system.
• Nephrology – The branch of science concerned with the study, diagnosis, and treatment of diseases related to the kidneys.
• Neurology – The branch of science concerned with the study, diagnosis, and non-surgical treatment of the nervous system and diseases that affect it.
• ENT – It is the branch of science that deals with diseases related to the ear, nose, and throat and their treatment.

Question 56.
Analyse the description given on page 162 of the textbook and complete Table 5.7 appropriately.

Answer:

Question 57.
Do other animals have blood groups? Find out.
Answer:
Each species has its own blood group system. These differ from the ABO system in humans. These groups are determined based on the presence or absence of proteins and antigens on the surface of red blood cells.

Answers to the indicators on page 162 of the textbook
Question 58.
Basis of blood groups:
Answer:
Blood groups are determined by the presence of the A antigen and the B antigen present on the surface of RBCs. The type of antigen present in the blood determines the blood group.

Question 59.
Antibodies present in each blood group:
Answer:

1. A group – antibody b
2. B group – antibody a
3. AB group – no antibodies
4. group – antibodies a and b.

Question 60.
Rh factor and blood groups:
Answer:
In addition to A and B antigens, some individuals have another antigen called the D antigen. If D antigen is present, the blood group is called positive; if absent, it is called negative. Since the D antigen was first discovered in Rhesus monkeys, it is also known as the Rhesus factor (Rh factor).

Question 61.
Importance of determining blood group in blood transfusion:
Answer:
If the donor’s blood contains an antigen that is naturally absent in the recipient’s blood, the antibodies present in the recipient’s plasma may act against it, leading to agglutination of the blood. Therefore, it is essential to consider blood groups in blood transfusion.

Question 62.
Is there a threat of plant diseases in your area? Prepare a project report by interviewing local farmers and the agricultural officer about the diseases and the control measures they have adopted, and present in the class.
Answer:
A sample project report is given below:

• Introduction: The objective of this project was to study the major diseases affecting agricultural crops in our region, how they affect farmers economically, and the scientific preventive measures adopted by the Agriculture Department to control these diseases. For this, information was collected by visiting the farms and the Agriculture Office in the region.
• Include an interview questionnaire conducted with farmers and Agriculture Officers
• Add information about one of the most threatening diseases from the interview and other studies.
• Conclusion: Currently, diseases like blight in rice and bunchy top in banana are a major threat in our region. Although farmers rely on chemicals to control these diseases, it is essential to implement integrated pest management, which includes resistant seeds, organic pesticides, and regular inspections as per the instructions of the Agriculture Department.

Question 63.
Do plants have an immune system like animals?
Answer:
Yes, plants have an immune system to protect against pathogens, but it is an innate immune system that is distinct from the animal immune system. Key differences include the absence of specialized immune cells and an adaptive immune system in plants; instead, plants rely on cell-surface and intracellular immune receptors to detect microbial molecules and launch defensive responses like producing antimicrobials and reinforcing cell walls.

Std 10 Biology Chapter 5 Notes – Extended Activities

Question 1.
Organise a blood group determination camp in the school under the auspices of the Health Club and prepare a Blood Group Directory.

Question 2.
Conduct a survey to find out the vaccination status of school children in your area and plan awareness programmes accordingly.
Answer:
Tips to include in an awareness campaign about the importance of vaccination:

• The fundamental importance of vaccination
• Individual and societal benefits
• Dispelling common doubts and misconceptions
• Raising awareness about authoritative sources
• Providing an opportunity to share the experiences of those who have recovered from the disease or avoided the disease through vaccination.

Question 3.
Prepare an action plan to eliminate mosquitoes at home and in your school and submit the report to the concerned authorities of the school and the Panchayath.
Answer:
Below are some important tips and suggestions for preparing an action plan to eliminate mosquitoes in homes and schools:
Action Plan Step 1: Identify and eliminate breeding sites.

In homes:

• Standing water
• Sewage
• Coolers/fridge trays
• Water tanks

In schools:

• Playgrounds/premises
• Tanks and pipes
• Garden/farming

Action Plan Step 2: Prevention Methods In homes and schools:

• Install mosquito nets on windows and doors.
• Encourage children to wear long clothing that covers their arms and legs, if possible, to avoid mosquito bites.
• Use mosquito nets when sleeping.

Action Plan Step 3: Awareness and Monitoring In schools:

• Campaigns
• Form a mosquito control monitoring squad, including children.
• Weekly “Dry Day”

In homes:

• Family meetings
• Regularly ensure that there is no water stagnation in the terrace of the house, rainwater pipes, and air conditioner drainage.

Question 4.
Conduct interviews with the agricultural officer, veterinary doctor and farmers to learn about plant and animal diseases in your area, prepare a presentation and present it in class.
Answer:
Questions for interviewing the Agriculture Officer:

1. What are the major agricultural crops in the area and the diseases that mainly affect them?
2. What was the plant disease that caused the most damage this year? What is its cause?
3. What are the current aids and subsidies provided by Krishi Bhavan for disease control?

Questions to interview a veterinarian:

1. What are the main diseases that affect domestic animals (cattle, poultry, goats, pigs) in your area?
2. Have zoonotic diseases (transmitted from animals to humans) been reported in the area? What precautions are taken to prevent them?
3. What are the awareness programs provided by the veterinary hospital to prevent recurrence of the disease after treatment?

Questions to interview farmers:

1. What are the diseases that mostly affect your crops and livestock?
2. Are you satisfied with the assistance you receive from the Krishi Bhavan or the Agriculture Officer?
3. What are two main suggestions you would like to put forward to improve the plant and animal disease control system in this area?

Immunity and Healthcare Class 10 Notes

Immunity and Healthcare Notes Pdf

• Health is a state of complete physical, mental, and social well-being.
• Anything that can enter our bodies and cause disease, including germs, can be called antigens. Germs, pollen, dust, some foods, and chemicals are all examples of antigens.
• The immune system is the body’s ability to prevent the entry of pathogens and destroy pathogens that have entered. These are of two types: innate immunity and acquired immunity.
• Phagocytosis is the process by which white blood cells engulf and destroy pathogens.
• The inflammatory response is a way to increase blood flow to the area of a wound or injury and recruit white blood cells to fight infection.
• Fever is a condition in which the body’s temperature rises above normal (98.6°F or 37°C).
• Blood clotting is a way to stop blood flow and prevent the entry of germs when there is a cut on the skin.
• Lymphocytes are the main cells responsible for acquired immunity. There are two types of lymphocytes – T lymphocytes and B lymphocytes.
• Vaccines act as antigens in the body. This stimulates our immune system to produce antibodies against pathogens.
• Immunisation is an artificial way of preparing Immune cells for a potential attack by a pathogen. The immunity acquired in this way is called artificial immunity.
• Acquired diseases are diseases that occur during a person’s lifetime. In addition to these, there are also hereditary diseases. Environmental factors, pathogens, lifestyle, etc., can all cause such diseases.
• Most infectious diseases are caused by microorganisms. Such diseases are known as contagious diseases. Such diseases can be transmitted by bacteria, viruses, fungi, protozoa, and worms.
• Cancer is a non-communicable disease. It is a condition in which cells multiply through abnormal and uncontrolled cell division and spread to other parts of the body.
• Hereditary diseases are diseases caused by genetic defects. Sickle cell anaemia and haemophilia are examples of some such diseases.
• In different parts of the world, treatment methods have been developed according to the lifestyle, culture, and available natural resources of the respective region. Ayurveda and Unani are traditional treatment methods that have evolved over time.
• Antibiotics are drugs that are made from microorganisms or are synthetically produced and used against bacteria.
• Blood transfusion is the process of transferring blood or blood components from one person to another. The person who gives blood is called a donor, and the person who receives blood is called a recipient.
• The study of diseases affecting animals and plants, their symptoms, causes, and methods of control are important fields in biology, agriculture, and veterinary sciences.

INTRODUCTION

Health
Health is the greatest wealth and blessing in human life. According to the definition of the World Health Organisation (WHO), “Health is a state of complete physical, mental and social well-being and not merely the absence of disease, or infirmity.”

Innate and acquired immunity
Immunity is the natural ability of an organism to protect its body from pathogens and other foreign substances. The immune system of humans and other organisms mainly relies on two types of immunity:

• Innate Immunity: This is a general and non-specific immunity that exists in a person at birth.
• Acquired or Adaptive Immunity: This is immunity that is acquired during a person’s life through exposure to diseases or through vaccination.

Acquired diseases
Acquired diseases are diseases that a person does not have at birth or are not genetically inherited, but are acquired during life. Acquired diseases can be divided into two broad categories based on their nature: communicable diseases and non-communicable diseases. In modern healthcare, the increase in these communicable diseases is a major challenge. A healthy lifestyle and preventive measures (vaccination, hygiene) are essential to prevent and control them.

Cancer
The human body is made up of billions of cells. These cells grow, divide, and die when needed in an orderly process. However, cancer is a condition in which this natural growth control is lost. There is no single-cause for cancer. Many factors can cause cancer, including genetic factors, unhealthy lifestyle choices such as smoking and alcohol consumption, ultraviolet rays,
certain types of viruses (for example: HPV), and environmental toxins.

Hereditary diseases
Hereditary diseases are diseases that are passed down from a person’s parents or ancestors to the next generation through genetic factors. These fall under the larger category of genetic disorders. Haemophilia and sickle cell anaemia are examples of such diseases.

Treatment
Treatment refers to all activities performed to alleviate, eliminate, or mitigate the effects of a disease, injury, or other health-related issue. The basic goal of treatment is to restore or maintain human health and well-being. There are various types of treatment methods in modern medicine.

Blood transfusion
Blood transfusion is the process of transferring blood or blood components into a patient’s body through veins. It is a treatment method that is used frequently all over the world to save lives. Blood transfusion is a process that must be done with great care. This is because incompatibilities in blood group and Rh factor between the donor’s blood and the recipient’s blood can cause serious reactions. Therefore, it is essential to perform accurate tests such as cross-matching before donating blood.

Animal and plant diseases
Diseases are defined as abnormal conditions in living organisms that threaten the survival, food supply, and economic security of living organisms on Earth. The study of diseases affecting animals and plants, their symptoms, causes, and methods of control are important areas of biology, agriculture, and veterinary sciences.

HEALTH

• Health is a complete state of physical, mental and social well-being. It means not merely the absence of disease or infirmity.
• Drug abuse is one of the biggest threats to health.
• Apart from drugs, the list of other factors that adversely affect health are:
  • Pathogens
  • Malnutrition
  • Environmental factors (pollution, chemicals)
  • Poor diet
  • Lack of exercise
  • Stress
• Any change in the homeostasis of the body due to these factors is called disease.
• Pathogens around us cause different types of diseases. They enter our body in many ways.

Antigens

• Anything, including pathogens that enter our body and cause diseases, is called an antigen.
• Pathogens, pollen grains, dust, certain food items, chemicals, etc., are examples of antigens.

Immunity
Immunity is the ability of the body to prevent the entry of pathogens and to destroy those that have already entered. Some of them are innate and some others are acquired.

INNATE IMMUNITY

• The natural immune mechanism that exists in the body by birth is called innate immunity.
• Innate immunity includes various mechanisms to prevent antigens from entering the body. These are generally called primary level immunity.
• If the pathogens bypass the primary level immunity and enter the body, the innate immune system that defends against them is called the secondary level immunity.
• It includes the coordinated action of defence mechanisms that destroy the pathogens that have entered the body.
• White blood cells are mainly involved in secondary-level immunity.
• All innate immune functions are independent of the type or mode of action of the pathogens. Therefore, they are called non-specific immunity.

PHAGOCYTOSIS

• Phagocytosis is the process by which white blood cells engulf and destroy pathogens.
• The blood cells that take part in phagocytosis are called phagocytes.
• White blood cells such as neutrophils and monocytes are phagocytes.

INFLAMMATORY RESPONSE

• It is the process by which blood flow increases to the injured or bruised area to bring white blood cells to fight an infection.
• The cells at the injured part releases histamine and other chemical substances. This dilates the blood vessels.
• As blood flow increases, blood cells such as monocytes and neutrophils reach the injured area.
• They engulf and destroy the pathogens.

Fever

• Fever is the condition that occurs when the body temperature rises above the normal range (98.6° F or 37° C).
• When infection or inflammation occurs, white blood cells release chemical substances called pyrogens. These trigger the brain to raise the body temperature.
• Fever is a kind of immune mechanism.
• High temperature helps phagocytes to destroy pathogens more quickly by engulfing them, inhibit the growth of pathogens, and enhance immunity.
• This is a sign that the body is fighting against the disease.
• Once the infection is gone, the body temperature returns to the normal level.

CLOTTING OF BLOOD

• It is a mechanism to prevent the flow of blood as well as to block the entry of pathogens into the body when a wound forms on the skin.
• When an injury occurs, the platelets and damaged tissues at the site produce an enzyme called thromboplastin. This converts a protein in the blood plasma called prothrombin into thrombin.
• Thrombin then converts an inactive protein called fibrinogen into fibrin.
• The fibrin forms a network of fibres that traps red blood cells, forming a blood clot.
• This clot prevents further blood loss until the wound is healed.

Wound healing

• As blood clots and inflammation occur at the wound, new tissues are formed, leading to wound healing.
• If the wound is healed with connective tissue replacing the lost tissues, a scar will remain.

ACQUIRED IMMUNITY

• This is the immunity that develops after birth.
• This immune mechanism specifically recognises and defends antigens (like the pathogens) that enter the body. Hence, this is also called as specific immunity.
• This immune defence is primarily carried out by lymphocytes. There are two types of lymphocytes -T lymphocytes and B lymphocytes.

VACCINES

• In deadly diseases like Diphtheria and Tetanus, by the time natural immunity develops and becomes effective, the pathogens will have multiplied and the chances of death are high.
• In such situations, we have to rely on artificial immune mechanisms. Vaccines are the substances used for this.
• Vaccines act as antigens in our body.
• It stimulates our immune system and helps to produce antibodies against the pathogens.
• These antibodies remain in the body and provide long-term protection against diseases. By taking the doses accurately vaccines help to gain protection from a disease for many years or even for a lifetime.
• There are many vaccines available, including MMR, OPV, HPV, and the COVID-19 vaccine.
• Immunisation is an artificial method of preparing the immune cells in advance, expecting the attack of pathogens. The immunity acquired in this way is called artificial immunity.

ACQUIRED DISEASES

• Malfunction of the immune system, genetic defects, unhealthy lifestyle, abundance of pathogens etc. disrupt the homeostasis of the body and cause diseases.
• There are diseases that occur during a person’s lifetime and also diseases that are inherited.
• Diseases which occur during the course of one’s life are called acquired diseases. Environmental factors, pathogens, lifestyle etc. may cause these diseases.
• There are communicable and Non-communicable diseases.
• Most communicable diseases are caused by microorganisms. Such diseases are known as contagious diseases.

BACTERIA

• When bacteria enter the body and multiply, the toxins released by them destroy the host tissues and disrupt bodily functions.
• Some produce enzymes that damage the cell membrane and destroy cells.
• Tuberculosis and Leptospirosis are some diseases spread by bacteria.

VIRUS

• Viruses enter the body and multiply using the genetic mechanism of the host cells.
• Thereby, they destroy the cells and cause diseases.
• AIDS and Nipah are examples of diseases transmitted by viruses.

a) AIDS (Acquired Immuno Deficiency Syndrome)

• Pathogen: Human Immunodeficiency Virus (HTV).
• Affects T lymphocytes.
• The virus attacks, and destroys them by multiplying using the genetic mechanism of T lymphocytes. As a result, the body’s ability to fight diseases is reduced and gradually the condition reaches to AIDS.
• Symptoms: Primary symptoms are similar to other viral diseases, but when the immunity decreases, fatal diseases such as Pneumonia, Tuberculosis, some types of cancer, etc., may develop.
• Mode of Transmission: HIV can be transmitted through sexual contact with an infected person, by sharing needles and syringes that are not HTV-free, through transfusion of blood or organs containing HIV, and from an infected mother to the foetus.
• Treatment – Currently, there is no medicine to completely cure AIDS. However, through Antiretroviral Therapy (ART), it is possible to control the multiplication of the virus and maintain the patient’s immunity.
• Scientists are working on technologies like CRISPR gene editing to cut and remove the HTV virus gene from cells.
• Along with this, efforts are also underway to develop medicines that ean activate and destroy the hidden HIV in the body, as well as to discover an effective HIV vaccine.

b) Nipah

• Pathogen: Nipah virus
• Symptoms: Fever, headache, muscular pain, cough, and vomiting are the initial symptoms. As the disease becomes severe, disorientation, epilepsy, and loss of consciousness may occur.
• Mode of transmission:

Treatment: Only supportive care is available to reduce the symptoms and complications of the disease. There are currently no antiviral medicines or vaccines.

FUNGUS

• Fungi can also cause various types of diseases in humans.
• These may directly infect the skin and nails, or produce toxins, leading to different diseases.

PROTOZOA

• They are unicellular eukaryotes.
• Some protozoa infect the red blood cells, multiply inside them and destroy them.

• Some others release harmful substances that affect the physiological activities.
• Malaria is a disease spread by protozoa.
• The protozoan named Plasmodium is the pathogen. Female Anopheles mosquito transmits this pathogen from one person to another.

• Symptoms: Intermittent fever, chills and shivering, headache, vomiting, muscular pain, body pain and fatigue.
• Treatment: Antimalarial medicines are used.

WORMS

• The parasitic worms such as pin worm, round worm etc. cause diseases.
• These diseases are generally known as worm infestations.
• The infection spreads through habits like nail- biting, eating without washing hands, or drinking contaminated water.
• Worm infestation causes fatigue, lack of enthusiasm,’tiredness, lack of concentration, nutritional deficiency, loss of appetite, weight loss, stomach pain, dizziness, and vomiting.
• Albendazole destroys various types of worms and helps prevent worm infestation. Albendazole tablets are effective in preventing the spread of worm infestation too.

a) Filariasis

• Filariasis occurs when filarial worms lodge in the lymphatic vessels and obstruct the normal flow of lymph.
• Female culex mosquitoes transmit these pathogens from one person to another.

• When a mosquito bites, the larvae of the worms enter the bloodstream, grow, and reach the lymphatic vessels and settle there.
• As a result, lymphatic fluid accumulates, and over time, body parts such as legs, arms, and
  genital organs become excessively swollen and enlarged.

CANCER

• Cancer is a non-contagious disease.
• Cancer is a condition in which abnormal and uncontrolled cell division leads to the multiplication of cells.
• This spreads to other parts of the body. When the control mechanisms of the cell division process fail, normal cells turn into cancer cells.
• Cancer cells spread to other parts of the body through the blood and lymph.
• Causes of Cancer: Genetic changes, Environmental factors, Viral infections, Lifestyle
• Treatment Methods: Surgery, Chemotherapy, Radiation therapy. Immunotherapy. Targeted therapy, Hormone therapy, etc. are the treatment methods.

HEREDITARY DISEASES

• Diseases caused by genetic defects are called hereditary diseases.
• Sickle cell anaemia and haemophilia are examples of such diseases.

TREATMENT

• In different parts of the world, treatment methods have evolved according to the lifestyle, culture, and available natural resources of the respective region.
• Ayurveda and Unani are traditional treatment methods that have evolved in this way.

AYURVEDA

• Ayurveda is a world-renowned system of treatment that originated in India.
• It aims at maintaining the balance of bodily functions through diet regulation, herbal medicines and exercise.
• In Ayurveda, plant and animal-based substances are used as medicines.
• Charaka is known as the Father of the Ayurvedic system of treatment.

HOMEOPATHY

• Homeopathy is a system of treatment introduced by the German doctor Samuel Hahnemann.
• This is a method of treatment that uses diluted doses of natural substances that cause symptoms in a healthy person to prevent disease.

MODERN MEDICINE

• The foundation of modern medicine was laid by the Greek physician Hippocrates.
• This system corrected superstitions related to diseases and gave importance to pathogens, diagnosis and the medicines.

MEDICINES

• Following the diagnosis, various medicines are used for treatment.
• These may be derived from plants, animals, microorganisms, or they may be artificially synthesised.
• Among these, antibiotics deserve special mention.

ANTIBIOTICS

• Antibiotics are medicines that are either derived from microorganisms or produced synthetically, and are used
• against bacteria.
• Although they are the most effective medicines available to treat bacterial diseases, their unscientific and excessive use can lead to several side effects.
• Some of these side effects include:
  • Problems in the digestive system such as diarrhoea, vomiting and stomach pain
  • Allergy
  • Damage to the liver and kidneys
  • Destruction of beneficial bacteria in the intestine
  • Resistance against antibiotics (Antibiotic resistance)
• A major concern is antibiotic resistance, which is developed in bacteria. This makes treatment more complicated.
• Use antibiotics only as prescribed by a doctor.

Alexander Fleming and Penicillin

Scottish bacteriologist Alexander Fleming accidentally discovered penicillin in 1928. While examining a petri dish containing Staphylococcus bacteria, he noticed that a fungus called Penicillium notatum had grown on it and was destroying the bacteria. This was the first antibiotic in the world that could kill bacteria without harming human cells.

Although Fleming could not purify penicillin himself, after a decade, Howard Florey and Ernst Boris Chain succeeded in purifying it and began large-scale production during the Second World War. This discovery revolutionised medical science. In 1945, Fleming, Florey, and Chain were awarded the Nobel Prize for this work. This led to the beginning of the antibiotic era.

BLOOD TRANSFUSION

• The process of transferring blood or its components from one person to another is called blood transfusion.
• The person who gives blood is known as the donor, and the person who receives blood is called the recipient.
• Blood groups are determined by the presence of A antigen and B antigen present on the surface of RBCs.
• The type of antigen present in the blood determines the blood group.
• The antibodies present in the plasma also play an important role in blood transfusion.
• In addition to A and B antigens, some individuals have another antigen called the D antigen. If D antigen is present, the blood group is called positive; if absent, it is called negative.
• Since the D antigen was first discovered in Rhesus monkeys, it is also known as the Rhesus factor (Rh factor).
• If the donor’s blood contains an antigen that is naturally absent in the recipient’s blood, the antibodies present in the recipient’s plasma may act against it, leading to agglutination of the blood. Therefore, it is essential to consider blood groups in blood transfusion.

ANIMAL AND PLANT DISEASES
Diseases affect not only humans but also animals and plants.

ANIMAL DISEASES

PLANT DISEASES

IMMUNITY IN PLANTS

• A rigid cell wall, epidermis and waxy coating on leaves and stems prevent the entry of pathogens.
• Antimicrobial substances either kill pathogens or inhibit their growth.
• Enzymes break down the cell walls of pathogens.
• The cells in the infected area undergo autolysis to prevent the spread of the disease.
• When one part of the plant is attacked, it sends warning signals from cell to cell about the disease.
• If pathogens cross the cell wall and enter, a polysaccharide called callose prevents their spread.

A thorough understanding of SCERT Kerala Syllabus 10th Standard Biology Notes Pdf and Class 10 Biology Chapter 6 Biology and Technology Notes Questions and Answers English Medium can improve academic performance.

SSLC Biology Chapter 6 Notes Questions and Answers Pdf Biology and Technology

SCERT Class 10 Biology Chapter 6 Biology and Technology Notes Pdf

SSLC Biology Chapter 6 Questions and Answers – Let Us Assess

Question 1.
Which of the following statements about recombinant DNA technology is correct?
I. Restriction enzymes are used to cut the DNA of an organism.
II. Ligase enzymes join the cut DNA fragments together.
III. Vectors are usually bacterial plasmids.
IV. When recombinant DNA enters a host cell, it does not replicate.
a) I and II only
b) I, II, III only
c) I, III, IV only
d) I, II, III, IV all
Answer:
b) I, II, III only

Question 2.
Identify A, B, and C and choose the correct option.
A: A technology that joins together DNA segments from two or more different organisms
B: A technology used to locate genes in DNA
C: A technology used to identify individuals by analysing the arrangement of nucleotides in DNA

i) A – Recombinant DNA Technology, B – Gene Mapping, C – DNA Fingerprinting
ii) A – Human Genome Project, B – Gene Therapy, C – CRISPR Technology
iii) A – Recombinant DNA Technology, B – DNA Fingerprinting, C – CRISPR Technology
iv) A – Gene Therapy, B – Gene Mapping, C – Human Genome Project
Answer:
i) A – Recombinant DNA Technology, B – Gene Mapping, C – DNA Fingerprinting

Question 3.
What is the importance of the host cell in recombinant DNA technology? Analyse how this technology would be limited if there were no host cells.
Answer:
The importance of the host cell in recombinant DNA technology:

• Multiplication: The host cell makes many copies of the recombinant DNA through cell division. This process is called cloning. When a new DNA molecule is introduced into 100,000 cells, the DNA multiplies in each cell to make many copies.

• Expression: The host cell helps the gene contained in the recombinant DNA (for example, the gene for making insulin) to fulfil its purpose. The host cell’s RNA and ribosomes produce the necessary protein (for example, insulin) according to the instructions of this gene.

Without a host cell, recombinant DNA technology would not be able to exist in its current form. All of the following would be limited:

• Quantitative limitation: Recombinant DNA is produced in very small quantities. We get this DNA in sufficient quantities because it multiplies in the host cell. Without a host cell, we would not be able to produce the required amount of DNA or protein.

• Protein production limitation: Recombinant DNA technology is used to produce proteins such as insulin, vaccines, and enzymes. Without a host cell, these genes cannot make proteins.

• Gene therapy limitation: In gene therapy, a new gene is introduced into a patient’s cells to try to reverse the disease. Without a host cell, this new gene would not be able to function in the patient’s body.

Question 4.
Analyse how the information provided by the Human Genome Project will help in the future development of recombinant DNA technology, CRISPR editing technology and Al in biology.
Answer:
a) Human Genome Project (HGP): The Human Genome Project helped to understand the complete structure of human DNA. It provides information about the location of each gene, their function, and how changes in them cause diseases.

b) Recombinant DNA Technology: Recombinant DNA technology helps to cut out the desired genes and make new combinations using the information provided by HGP. For example, the gene that produces insulin was found and transferred to bacteria to produce large amounts of insulin.

c) CRISPR Editing Technology: CRISPR is the next generation of recombinant DNA technology. It makes gene editing easier, faster, and more precise. It helps to edit any part of the human genome. Using the information obtained from HGP, it is possible to accurately identify genes that cause diseases and use CRISPR to correct them. This will make a big difference in the treatment of hereditary diseases in the future.

d) AI in Biology: AI plays a major role in integrating these three technologies. AI helps in analysing large data sets like the Human Genome Project and finding hidden patterns and relationships in it. AI can be used to predict diseases and develop personalised treatments. AI can analyse a patient’s genome and suggest the most suitable medicine for them.

Question 5.
How can the use of genome data be helpful in prescribing drugs that are appropriate for the patient?
Answer:
Genomic data can be used to understand how a drug will work in a patient.

Each person’s genome contains genes that control enzymes responsible for breaking down drugs. Small differences (called genetic variations) in these genes can cause drugs to be broken down very quickly in some people and very slowly in others. Analysing a patient’s genome can help determine which group they belong to and aid in determining the right dose of the drug. Some drugs cause serious side effects only in some people. The genetic variations that cause these side effects can be found in genomic data. Some drugs work in one group of patients but not in another. By studying their genomes, it is possible to find out which patients are more likely to benefit from a particular drug.

Question 6.
Analyse the fundamental similarities and differences between recombinant DNA technology and gene therapy.
Answer:
Similarities:

• Use of genetic molecules: Both technologies are based on genetic molecules such as genes, DNA, or RNA.
• Use of vectors: Both technologies use vectors such as viruses to deliver new genes into cells.

Differences:

Question 7.
Observe the illustration and answer the questions.

a) Name the technology indicated in the illustration.
b) Identify and name A and B.
c) What is the role of A and B?
Answer:
a) The illustration refers to the CRISPR-Cas 9 gene editing technology.

b) A is the guide RNA (gRNA) and B is the Cas 9 protein.

c) CRISPR uses an enzyme called Cas9 (B) as scissors to cut DNA. It also includes an RNA that identifies the DNA segment to be cut. This is called as guide RNA (gRNA) (A)

Question 8.
Imagine that you have received a DNA fingerprinting report in a forensic case. Explain how the perpetrator can be identified by analysing the patterns in this report. How can this technology be used to identify the unidentified dead bodies found in natural disasters?
Answer:
To identify a criminal from a DNA report, repeated DNA patterns at specific locations are analysed, comparing the number and length of repeating DNA sequences between crime scene evidence and suspect samples. For unidentified bodies after a natural disaster, this technology identifies victims by comparing their DNA profiles to reference samples from their families or other biological material found at the scene.

Question 9.
How does artificial intelligence (AI) help data analysis and discoveries in biological research?
Answer:
AI plays a key role in many areas of biological research, such as disease diagnosis, drug discovery, and genetic engineering
BIOLOGY AND ARTIFICIAL INTELLIGENCE (AI)

• AI plays a major role in many areas of biological study, including disease diagnosis, drug discovery and genetic engineering.
• Bioinformatics is a new scientific discipline of science that analyses biological data by combining the latest technological disciplines such as computer science, mathematics and statistics.

Potential applications of artificial intelligence (AI) in biological fields:

• Diagnosis, treatment: For discovering new drugs, for predicting the effectiveness of chemical substances and recommendation of the most suitable treatment.
• Personalised medicine: analyses each individual’s genetic makeup and health information and recommends the most suitable treatment regimens for them.
• Genome sequencing: Utilised in gene editing technology for the treatment of genetic disorders.
• Improving agriculture: Monitors the health of the soil, predicts the diseases that might affect crops.
• Pollution: Predicts air and water pollution levels and recommends mitigation strategies.
• Bioinformatics: Analyses large amounts of genetic data and suggests simplification strategies

Question 10.
Prepare a note on the following concepts to present in a seminar on the possibilities of technology for environmental conservation:
i) Data Collection
ii) Biodiversity Conservation
iii) Pollution Control
Answer:
Technology plays a crucial role in environmental protection, data collection, biodiversity conservation, and pollution control. Technologies such as satellite remote sensing, drones, and sensors can be used to monitor the condition of forests and water resources in real time and quickly identify the source of pollution. Gene banking technology can be used to preserve the genes of endangered species. Similarly, biodiversity can be preserved by developing resistant plants and animals. In addition, microbiology can be used to remove wastes such as oil through bioremediation and reduce pollution by using renewable energy sources.

Biology Class 10 Chapter 6 Notes Kerala Syllabus Biology and Technology

Question 1.
How is genetic constitution altered through recombinant DNA technology?
Answer:

Answers to the indicators on page 170 of the textbook
Question 2.
Recombinant DNA Technology:
Answer:
Recombinant DNA technology combines DNA segments from two or more different organisms to form recombinant DNA.

Question 3.
Enzymes and their functions:
Answer:
a) Restriction Endonuclease Enzyme: The genetic scissor that cuts a specific gene
b) Ligase enzyme: Genetic glue that joins two DNA segments.

Question 4.
Vectors-fiinction:
Answer:
Vectors carry the genes and a host cell into which the recombinant DNA is inserted, (circular DNA), and some viruses are used as gene carriers or vectors)

Question 5.
Various stages of recombinant DNA technology:
Answer:

• Cuts the desirable gene from human DNA
• Cuts the plasmid and removes a specific part
• The cut human gene is ligated to the plasmid
• The plasmid with the incorporated human gene is inserted into the host cell.
• As the inserted genes become active in the cell, the desired products are formed.

Question 6.
This technology is widely used in various fields. An example for this is the production of human insulin using bacteria. What are the other fields in which this technology is used?

a) Medicine

• Hormones: This technology helps in the production of important hormones such as human insulin and human growth hormone.
• Vaccines: Vaccines are developed against diseases such as hepatitis B using the DNA of pathogenic microorganisms.
• Gene therapy: This technology is used to replace damaged genes with healthy genes to treat certain inherited diseases.

b) Agriculture

• Genetically Modified Crops: Recombinant DNA technology is used to produce crops that are resistant to pests and diseases. This helps reduce the use of chemical pesticides. For example, BT Cotton.
• Increased Yield: Crops are developed that are more resistant to drought and adverse weather conditions.
• Nutrient-rich crops: This is used to produce plants with higher nutrient content. For example, Golden Rice with increased levels of vitamin A.

c) Industry

• Enzyme production: This technology helps produce enzymes needed to make cheese, biofuels, and detergents.
• Pollution control: Genetically modified microorganisms can be used to remove pollutants such as oil and mercury from the environment.

Question 7.
Is CRISPR technology the only technology used in gene editing? Find out.
Answer:
No, CRISPR technology is not the only technology used for gene editing; other technologies such as zinc finger nucleases (ZFNs), transcription factor-like effector nucleases (TALENs), and mega nucleases existed before it. The CRISPR-Cas9 system has become very popular due to its ease of use, low cost, and precise operation.

Answers to the indicators on page 171 of the textbook
Question 8.
CRISPR technology:
Answer:
CRISPR is a modern technique used to edit DNA with extreme precision.

Question 9.
Guide RNA, Cas9 enzyme:
Answer:
CRISPR technology uses an enzyme called Cas9 as scissors to cut DNA. It also includes an RNA that identifies the DNA segment to be cut. This is called as guide RNA (gRNA).

Question 10.
Gene editing:
Answer:
The arrangement of nitrogen bases in DNA can be edited in a way that is necessary to change the characteristics of an organism. This can remove unwanted traits or add new traits. This is called gene editing.

Answers to the indicators on page 172 of the textbook
Question 11.
The various fields in which beneficial changes are brought about, and the resultant changes.
Answer:
Agriculture: It has been possible to produce plants that are resistant to pests, weeds, and viruses. It is possible to ensure high production efficiency.
Health: It is also helpful in the production of hormones like insulin and vaccines, as well as in the diagnosis and treatment of diseases.

Question 12.
The changes that can be brought about in nature by genetically modified organisms:
Answer:

• If GMOs have a higher survival rate than normal organisms, they may multiply rapidly in nature. This could threaten native flora and fauna and lead to their extinction.
• Some genetically modified crops may have a negative impact on soil structure and microorganisms.
• Continued use of genetically modified crops may lead to pests developing resistance to them. This may force us to use more powerful pesticides.
• Genetically modified foods may cause allergies in some people.

Question 13.
Has the genome information of other organisms been discovered? Find out.
Answer:
In addition to the human genome, the genomes of thousands of animals, plants, bacteria, and fungi have already been analysed, and data collected.
Major organisms whose genomes have been studied include:

• Animals: dog, cat, monkey, rat, cow, chicken, pig, etc.
• Plants: rice, wheat, cassava, apple, grape, etc.
• Microorganisms: various bacteria, yeast, and viruses.

Answers to the indicators on page 173 of the textbook
Question 14.
Genome:
Answer:
The genome is the sum total of all the genetic materials in an organism.

Question 15.
Gene Mapping:
Answer:
Gene mapping is a technique used to locate genes in DNA.

Question 16.
Human Genome Project:
Answer:
The Human Genome Project was a global scientific initiative that began in 1990 and was completed in 2003, with the goal of completely understanding the information in the human genome.

Question 17.
List the various steps of stem cell therapy.
Answer:

• The stem cells that produce blood cells are collected.
• The active gene is incorporated into the stem cells using viruses as vectors.
• The stem cells incorporated with the gene are injected to the patient.

Question 18.
Analyse the illustration 6.5 a and find out how the relationship between parents and offspring is identified and also analyse illustration 6.5 b and identify the person to whom the sample resembles.

Answer:
Illustration 6.5a Analysis:
A child gets half of their DNA from their mother and half from their father. This will be reflected in the DNA fingerprinting.

1. Identify the individuals: Look at which lane the mother, father, and child DNA samples are in the image.
2. Compare the bands: Carefully examine each DNA band in the child’s lane.
3.  Find the relationship: Each of the child’s DNA bands must be in exactly the same position in either the mother’s lane or the father’s lane. That is, each band in the child must match either the mother’s or the father’s band. If the child does not have a single band in either of the parents, the child is not their biological child.

Illustration 6.5b Analysis:
Each person has a unique DNA structure (except for twins). This principle is used in forensic cases to identify criminals.

1. Identify the samples: Look at which row in the image is the sample from the crime scene and which row is the sample from the suspect.
2. Compare the patterns: Carefully compare the pattern of DNA bands of the unknown sample (labelled sample) with the pattern of each suspect.
3. Find an exact match: The person whose band pattern of the unknown sample matches the band pattern of the person exactly (all bands fall in the same position) is the owner of the sample. If not even one band matches, then the sample does not belong to him.

The sample in the given illustration matches that of person 2.

Answers to the indicators on page 176 of the textbook
Question 19.
DNA Fingerprinting:
Answer:
The technology that is used to analyse the sequence of nucleotides in DNA and to identify individuals accordingly is called DNA fingerprinting.

Question 20.
DNA Fingerprinting – basis:
Answer:
The basis of DNA fingerprinting is the differences in the repeating sequences in each person’s DNA. Although these repeating sequences are found in everyone, there are large differences in their number and arrangement from person to person.

Question 21.
Application possibilities of DNA fingerprinting:
Answer:
The possibilities of DNA fingerprinting are endless in forensic science, in proving paternity and relationships, in healthcare diagnostics, organ donation, and in crop management in agriculture.

Question 22.
Match with the sample and the culprit in the illustration:
Answer:
The person whose band pattern of the unknown sample in the illustration matches the band pattern of the person completely (all bands fall in the same position) is the owner of the sample. If not even one band matches, then the sample does not belong to him. The sample in the given illustration matches that of person 2.

Answers to the indicators on page 177 of the textbook
Question 23.
Microbiome:
Answer:
The human microbiome is the collection of microorganisms and their genes that inhabit and interact within the human body.

Question 24.
Microbiome Project:
Answer:
To develop knowledge about microorganisms, the Human Microbiome Project (HMP) was launched by the National Institutes of Health (NIH) in the United States in 2007.

Question 25.
Services provided by Microbiome:
Answer:

1. Improves digestion
2. Boosts immunity
3. Protects mental health
4. Prevents obesity
5. Produces vitamins and other nutrients.

Question 26.
Organise a seminar on the topic Biotechnology Opportunities and Challenges.
Answer:
Hint: (Below is an outline for organising a seminar on this topic. You can present the seminar using this outline).

Seminar: Biotechnology, Opportunities and Challenges

Introduction

• Importance of Biotechnology
• Major recent advances in this field
• Need to discuss the opportunities and challenges these technologies offer to humanity and nature.

Possibilities (Technologies and their benefits)
a) Genetic engineering:

• In health: gene therapy, vaccine production, production of artificial insulin.
• In agriculture: production of plants with higher yields and immunity (for example, BT cotton).

b) DNA fingerprinting:

• Forensics: helps to find criminals and identify bodies.
• Relationships: used to determine paternity and other family relationships.

c) Stem cell research:

• The potential to grow new cells and organs.
• Helps to regenerate damaged cells and treat and cure diseases.

Challenges (topics to discuss)
a) Genetically modified organisms (GMOs):

• Potential harmful changes they can cause in nature.
• Potential health problems in humans from eating genetically modified plants.

b) Ethical issues:
• Ethical concerns about modifying human behavior and abilities through gene editing.

c) Illicit use:

• Potential for misuse of these technologies to produce biological weapons.
• Concerns about the leakage of individuals’ genetic information.

Conclusion

• Biological technologies are a great opportunity, but it must be ensured that they are safe and ethical.
• The need to raise public awareness about this technology.
• The importance of society working together to use these technologies only for good.

Std 10 Biology Chapter 6 Notes – Extended Activities

Question 1.
Prepare a short video on the topic ‘The Role of the Microbiome in a healthy lifestyle’ by including the Human Microbiome Project, the importance of microorganisms in our body as well as their relationship with health and diseases, and present it under the leadership of Little KITES.
Answer:
Some helpful tips for making videos:
1. Start with an engaging question like, “Did you know there’s a microbial world inside you?”

2. Use simple language: Avoid technical terms like “microbiome” and simply say “the community of microbes in our bodies.”

3. Use visuals:

• Animation: Simple animations can show how bacteria digest food and help the immune system.
• Charts and images: Simple charts or images can be used to explain the structure of the microbiome.
• Similes: Simple similes can help make the idea clearer.

4. Keep it short and to the point: Reduce the length of the video. Focus only on the main points.

• Introduction: What is the microbiome?
• Content: How does it help us, and what happens if it becomes unhealthy?
• Conclusion: How can we keep it healthy?

5. End the video with a message like “Remember that the food you eat helps the microbes inside you make the world healthier.”

Question 2.
Organise a debate to discuss on the topic ‘The Social and Ethical Aspects of Biotechnology including Genetic Engineering’ by involving experts and the general public.
Answer:
Suggestions for discussion:
a) Moral aspects:

• Designer babies: Is it morally right to create ‘superior humans’ by rewriting the genes that determine intelligence and beauty? Won’t this create new kinds of inequalities in society?
• Human evolution: How will genetic engineering affect the natural evolution of humans? What changes will the creatures created by humans make in nature?

b) Socio-economic aspects:

• Economic inequality: Genetic treatments are likely to be very expensive. Will this become a privilege only available to the rich?
• Food security: Are genetically modified crops (GMOs) a solution to food shortages or will they cause health problems in the long run?

c) Legal aspects: How can we prevent the potential for misuse of these technologies? What should be the rules regarding keeping genetic information confidential?

Question 3.
Conduct a publicity campaign in schools and nearby areas, by using posters and pamphlets prepared on the importance of biotechnology.
Answer:

Question 4.
Prepare a science article exploring the possibilities and problems that could arise if gene editing were applied to humans.
Answer:
Some tips the writing an essay:

• Explain briefly what gene editing is and how technologies like CRISPR-Cas9 can help with this. Mention its importance in the field of human health.
• Potential (benefits): Treating hereditary diseases: It is possible to provide a permanent solution to genetic diseases such as cystic fibrosis and sickle cell anaemia.
• Enhancing immunity: Genes can be modified to increase the body’s immunity to fight HIV and some types of cancer.
• Problems and challenges (disadvantages): Safety issues: Gene editing technology is prone to errors. This can cause unwanted changes and lead to new diseases or other health problems.
•  Social implications: It is possible to create a new kind of social division between genetically enhanced humans and those who are not. This may create new conflicts in society.
•  Gene editing is a critical technology. Although it has great potential, it must be used responsibly and with legal restrictions. The article concludes by noting that more discussion and study is needed on how to use this technology for the welfare of humanity.

Biology and Technology Class 10 Notes

Biology and Technology Notes Pdf

• Biotechnology is the technology that uses living organisms or their parts to provide products and services that are useful to humans.
• Genetic engineering is the technology that creates desirable traits in organisms by adding or removing genes.
• Recombinant DNA technology combines DNA segments from two or more different organisms to form recombinant DNA.
• CRISPR is a modern technique used to edit DNA with extreme precision. It uses an enzyme called Cas9 as scissors to cut DNA. It also includes an RNA that identifies the DNA segment to be cut. This is called as guide RNA (gRNA).
• There are plants, animals, and microorganisms whose genetic constitutions have been altered through genetic engineering. They are called Genetically Modified Organisms (GMOs).
• The genome is the sum total of all the genetic materials in an organism.
• The Human Genome Project was a global scientific initiative that began in 1990 and was completed in 2003, with the goal of completely understanding the information in the human genome.
• Gene mapping is a technology that locates the location of genes in DNA.
• Gene therapy is a method of treating diseases by removing defective genes and replacing them with functional genes.
• DNA fingerprinting is a technique used to identify individuals by analysing the arrangement of nucleotides in DNA.
• The human microbiome is the collection of microorganisms and their genes that inhabit and interact with the human body.
• The Human Microbiome Project (HMP) is a project launched by the National Institutes of Health (NIH) in the United States in 2007 to expand knowledge about microorganisms.
• AI plays an important role in many biological fields such as diagnosis, drug discovery, and genetic engineering.
• Many biological techniques have been developed to help protect ecosystems and biodiversity. Technology plays a major role in effectively combating the challenges facing nature.

INTRODUCTION

Genetic Revolution
Human evolution is moving from a life in harmony with nature to the advanced era of biotechnology and artificial intelligence (AI). From the use of fire, agriculture, and social life, to major discoveries such as cell biology, genes, DNA analysis, and synthetic biology, humans are conquering new heights of knowledge. These advances are bringing about major changes in areas such as environmental protection, food security, agriculture, health, and industry. By producing artificial meat in labs, we can avoid slaughtering animals. Gene editing is beneficial for the agricultural sector. Similarly, DNA analysis in the field of forensics helps in identifying criminals. These technologies have the potential to change the future of humanity.

Biotechnology and Genetic Engineering
Biotechnology and genetic engineering are two related scientific disciplines. Biotechnology is a large branch of science that uses living organisms and their parts to develop products and technologies for the welfare of humanity. Genetic engineering is a sub-discipline of this. Genetic engineering is a technology that changes the genetic structure of an organism. It helps in cutting out genes, adding new genes, and controlling the functions of genes. Technologies like recombinant DNA technology and CRISPR-Cas9 are examples of this. These technologies have brought about great changes in sectors such as health, agriculture, and industry.

Genetically Modified Organisms – GMOs
Genetically modified organisms (GMOs) are plants, animals, or microorganisms that have had their genetic makeup scientifically altered. Typically, these alterations are made by removing a beneficial gene from one organism and inserting it into another.

Human Genome Project (HGP)
The Human Genome Project (HGP) is a large international research project that aims to understand the entire genetic makeup (genome) of the human body.

Begun in 1990 and completed in 2003, the project sequenced approximately 3 billion base pairs of human DNA and mapped approximately 20,000 – 25,000 genes in humans.

The project opened up new avenues for research into genetic diseases, their causes, and treatments. The information provided by the Human Genome Project is considered a maj or milestone in the study of biology and medicine.

Human Microbiome Project (HMP)
The Human Microbiome Project (HMP) is a large research project aimed at studying the community of microbes (the microbiome) inside and outside the human body. Its main goal is to understand how these microbes play a role in our health and disease. Like the Human Genome Project, this project is also providing new knowledge about our bodies.

Biology and Artificial Intelligence (AI)
In today’s scientific world, biology and artificial intelligence (AI) are rapidly merging. AI is helping to analyse biological big data, make new discoveries, and bring revolutionary changes in human health and agriculture. Genome studies, protein structure analysis, drug discovery, and disease diagnosis can all be made more efficient with AI.

Technological possibilities in environmental conservation
Modern technologies open up great possibilities for environmental protection. Today, technology is an important tool for scientifically tackling problems such as climate change, pollution, and biodiversity loss. Technologies such as remote sensing, drones, and artificial intelligence (AI) help monitor the environment and collect information. Similarly, biotechnology such as bioremediation and renewable energy sources provide new ways to control pollution and protect biodiversity. In short, technology plays a major role in effectively combating the challenges facing nature.

GENETIC REVOLUTION
Genetic technology is having a major impact on various areas of human life today. Instead of relying on animals for meat production, it is possible to produce artificial meat in labs using stem cells. This is already available in countries such as the USA, Israel, and Singapore. In addition, the development of immune-resistant plants through gene editing, for example, tomato plants that are resistant to fungal diseases, holds great promise for the agricultural sector. This technology is also crucial in the field of forensics; although the body could not be found in a murder case in 2020, the DNA analysis of a hair sample obtained from the suspect’s car was able to identify and convict the murderer. Such examples illustrate the growth of genetic technology and its practical possibilities.

From ancient humans who lived in harmony with nature, humanity has reached the modern era of biotechnology, genetics, and artificial intelligence (AI). From the use of fire, the beginning of agriculture, social life, and the domestication of animals, humans are conquering new heights of knowledge through great discoveries such as cell biology, genes, DNA analysis, and synthetic biology. From primitive man to modern man, and from there to the heights of biotechnology, other technologies, and artificial intelligence (AI), man is taking a step forward. Through this, environmental protection, food security, agriculture, health, and industry are all undergoing major changes.

BIOTECHNOLOGY AND GENETIC ENGINEERING
Biotechnology

• Biotechnology is the technology of using living things or their parts to provide products and services that are useful to humans.
• The discovery of the structure of DNA has accelerated the growth of biotechnology.

Genetic engineering

• Genetic engineering is the technology for creating desired traits in organisms by combining or deleting genes.
• For this, various technologies are used in genetic engineering.

RECOMBINANT DNA TECHNOLOGY
Recombinant DNA technology combines DNA segments from two or more different organisms to form recombinant DNA.
Key components of recombinant DNA technology and their functions:
a) Restriction Endonuclease Enzyme: The genetic scissors that cuts a specific gene
b) Ligase enzyme: Genetic glue that joins two DNA segments.
c) Vector: This carries the genes and a host cell into which the recombinant DNA is inserted, (circular DNA), and some viruses are used as gene carriers or vectors)
d) Host cell: The cell that receives the recombinant DNA.

CRISPR TECHNOLOGY

• CRISPR is a modern technique used to edit DNA with extreme precision.
• Emmanuel Charpentier and Jennifer A. Doudna discovered this technology.
• The CRISPR technology was designed from a natural defence mechanism that bacteria use, to defend viruses.
• It uses an enzyme called Cas9 as scissors to cut DNA.
• It also includes an RNA that identifies the DNA segment to be cut. This is called as guide RNA (gRNA).

GENETICALLY MODIFIED ORGANISMS (GMOs)
There are plants, animals, and microorganisms whose genetic constitutions have been altered through genetic engineering. They are called Genetically Modified Organisms (GMOs).

HUMAN GENOME PROJECT (HGP)

• Genes control our characteristics and activities.
• The genome is the sum total of all the genetic materials in an organism.
• The human genome contains approximately 300 crore DNA base pairs.
• The Human Genome Project was a global scientific initiative that began in 1990 and was completed in 2003, with the goal of completely understanding the information in the human genome.
• Gene mapping technology, which identifies the location of genes in DNA, has helped in this.
• The Human Genome Proj ect is a maj or milestone in biology.
• It is very helpful in understanding how genetic diseases arise and finding new treatments.

The following facts were discovered through this project:
a) The exact sequence of 300 crore base pairs in the human genome.
b) Humans have 20,000 to 25,000 genes.
c) Functional genes make up approximately 1 – 2% of human genome. The remaining bulk part is known as ‘junk DNA’. (Studies are going on about its exact functions.)

GENE THERAPY

Gene therapy is the method of treating diseases by removing the defective genes and replacing them with functional genes.

E.g., Sickle cell anaemia. This is a hereditary disease. Previously, there was no effective treatment for this disease. However, the World Health Organisation has approved gene therapy treatment to completely reverse sickle cell anaemia. This treatment method can be described as gene therapy or stem cell therapy, as it involves genetic modification of the stem cells of the patient and their injection back into the body.

How does gene therapy work?

Somatic gene therapy delivers healthy genes to body cells. Examples: muscles, liver, blood cells. The effect of this therapy will be only in the person being treated; that is, these changes in genes will not be passed on to the next generation. However, in germline gene therapy, the genes are transferred into the reproductive cells. The genetic changes that occur in this way will be transmitted to the next generations. This raises so many ethical and social questions.

DNA FINGERPRINTING

• The technology that is used to analyse the sequence of nucleotides in DNA and to identify individuals accordingly is called DNA fingerprinting.
• 99.9% of DNA is the same in all humans. Variations are seen in the remaining 0.1 % of the DNA of individuals.
• Just as fingerprints that vary from person to person, the sequence of nucleotides in each person also vary. This peculiarity helps to identify individuals.
• These differences are mainly seen in the parts of DNA that do not help to make proteins. In these parts, some DNA sequences are repeated.
• The number of repeats and their order differ in each individual.
• More resemblances can be seen in the DNA patterns of parents, their offspring and siblings.

British geneticist Sir Alex Jeffrey discovered DNA fingerprinting on 10 September, 1984, at the University of Leicester. While examining a DNA X- ray film, he realised that differences in the DNA patterns of individuals could be used to identify them. He also discovered that each individual has a unique DNA pattern, as unique as the fingerprint.

Uses of DNA Fingerprinting:

• To identify culprits
• To identify genetic disorders and learn about hereditary diseases
• To determine the biological relationship between parents and offspring
• To understand lineage by identifying fossils
• To identify victims of accidents or disasters
• To track endangered species

Organoids and 3D printing

Organoids are tiny, three-dimensional tissue models that are grown in the lab. They help to study diseases, test new drugs, and develop regenerative therapies. Currently, the shortage of donors, infection, and the tendency of the body to reject the new organ are major challenges in organ transplantation surgery. 3D printing of organs is a technology that can help to overcome these challenges. By using M.R.I or C.T scan the image of organs are collected. These images and bioinks (consisting of living cells, other organic materials and growth factors) are sent to the 3D bioprinter. Using the bioinks, the 3D bioprinter creates organ models. This technology could effect major changes in organ transplantation surgery in future.

HUMAN MICROBIOME PROJECT (HMP)

• The human microbiome is the collection of microorganisms and their genes that inhabit and interact within the human body.
• It is a community of microorganisms that includes bacteria, archaea, fungi and viruses.
• The number of microorganisms in our body is ten times more than the cells.
• They provide us with many services, including immunity, digestion, and the production and absorption of vitamins.
• To develop knowledge about microorganisms, the Human Microbiome Project (HMP) was launched by the National Institutes of Health (NIH) in the United States in 2007.
• HMP proved that the human body is not only composed of cells but also crores of microorganisms, and co-existence is essential for our well-being.
• It also revealed that the cause of disease is not only the pathogen but the change in the equilibrium of microorganisms in the body.
• This knowledge has opened new avenues for diagnostic and treatment methods.
• This project opened a great opportunity to design personalised medicine and to arrange treatment according to each individual’s microbiome.

The science that converts even feces to medicine

Our bodies are home to trillions of microbes working for us. The main ones are bacteria. Antibiotics are ineffective against serious intestinal infections caused by the drug-resistant bacterium Clostridium difficile. That’s where a new treatment using human feces as medicine comes in. For this treatment, beneficial bacteria that help with digestion are collected from the feces of a healthy person and put into capsules. When these “poop pills” are given to the patient, the number of good bacteria increases, and they can fight Clostridium difficile infections. The World Health Organisation (WHO) has approved the poop treatment. As strange as it may sound, this is an example of how science will take any path to solve a problem through its method.

TECHNOLOGICAL POSSIBILITIES IN ENVIRONMENTAL CONSERVATION
Numerous biological techniques have been developed to help conserve the ecosystems and biodiversity. The following are some examples:
a) Wildlife Tracking Sensors: These help wildlife conservationists and researchers to plan conservation strategies by monitoring the movement, behaviour, and location of wild animals.

b) Global Biodiversity Data Sensors: A technology that collects information about biodiversity using satellite remote sensing, acoustic analysis and camera traps

c) Cryopreservation: This is the process of preserving living cells, tissues and organs at very low temperatures (- 196°C). It is used for long-term preservation in fields such as medicine, agriculture and research.

d) Bioremediation: Uses microorganisms and plants to remove pollutants from contaminated environments such as soil, water and air. This converts the pollutants into harmless compounds.

A thorough understanding of SCERT Kerala Syllabus 10th Standard Biology Notes Pdf and Class 10 Biology Chapter 4 Chemoreception in Organisms Notes Questions and Answers English Medium can improve academic performance.

SSLC Biology Chapter 4 Notes Questions and Answers Pdf Chemoreception in Organisms

SCERT Class 10 Biology Chapter 4 Chemoreception in Organisms Notes Pdf

SSLC Biology Chapter 4 Questions and Answers – Let Us Assess

Question 1.
The illustration related to the transmission of hormones to their target cells is given below. Analyse it and answer the questions.

i. Write the function of A with respect to the formation of C.
ii. If A is the releasing hormone, where can B be found?
in. How does the secretion and transmission of A differ in plants and animals?
Answer:
i) Function of A (Hormone): It combines with B (Receptor) to form C (Hormone—Receptor complex).
ii) If A is a releasing hormone, B (Receptor) will be found in the pituitary gland.
iii) In animals, hormones are secreted into the blood and carried to target cells. In plants, hormones move cell- to-cell or through xylem and phloem.

Question 2.
The illustration given below is related to the regulation of calcium level in blood. Analyse it and answer the questions.

(a) Which hormone is indicated as 1?
(b) Redraw the illustration showing glucose instead of calcium.
Answer:
(a) 1. Calcitonin.
(b)

Question 3.
The amount of thyroxine in the blood decreases. Through various stages, the amount of thyroxine is brought back to an adequate level. List the actions that take place for this in order and the hormones responsible for it.
Answer:
Hypothalamus secretes TRH (Thyrotropin Releasing Hormone)
Stimulates Pituitary gland to secrete TSH (Thyroid Stimulating Hormone)
TSH stimulates Thyroid gland to produce Thyroxine
Thyroxine level returns to normal.

Question 4.
Is it possible to sleep during the day just as one can sleep at night? Justify your opinion by relating it to the functions of the pineal gland.
Answer:
Yes, sleep is possible during the day, but it is not as natural as at night. The pineal gland produces melatonin mainly in darkness at night, which induces deep sleep. Light reduces melatonin secretion, so daytime sleep is lighter and less effective.

Question 5.
The hypothalamus functions as part of the nervous system and the endocrine system. Evaluate the statement.
Answer:
The hypothalamus works as part of both systems: Nervous system: Regulates body temperature, hunger, thirst, and emotions.
Endocrine system: Produces releasing and inhibitory hormones that control the pituitary gland and, indirectly, other endocrine glands.
Hence, it acts as a link between nervous and endocrine systems.

Question 6.
‘A person runs very fast and escapes from a ferocious dog’. This incident involves the functions listed below. Write them in the correct sequence.
• Action of adrenal gland
• Action of the sympathetic nervous system
• Action of parasympathetic nervous system
Answer:
• Action of sympathetic nervous system.
• Action of adrenal gland.
• Action of parasympathetic nervous system.

Question 7.
Informat ion about a chemical substance is provided in the box.
Analyse it and answer the questions.

i) Which chemical substance is mentioned in the box?
ii) Write any two other properties of this chemical substance.
iii) How do farmers make use of this chemical substance?
Answer:
i) Pheromone.

ii) Other properties: Used for communication in same species; can signal danger, mark territory, attract mates, guide food trails.

iii) Farmers use pheromone traps to control pests in agricultural fields.

Question 8.
X, Y, and Z are the functions of different plant hormones.Analyse them and choose the correct option.

Answer:
X = Abscisic acid Y = Cytokinin Z = Auxin

Question 9.
Explain how the pancreas regulates the amount of glucose in the blood in the following situations.
• A person eats carbohydrate-rich food.
• A person fasts for 12 hours.
• A person has type-1 diabetes and takes insulin regularly.
Answer:
A person eats carbohydrate – rich food
Blood glucose increases – Insulin secreted – Stores glucose as glycogen – Blood sugar decreases.
A person fasts for 12 hours.
Blood glucose decreases – Glucagon secreted – Converts glycogen to glucose – Blood sugar rises.
A person has type-1 diabetes and takes insulin regularly.
Type-1 diabetic with insulin treatment: Since natural insulin is absent, injected insulin helps cells absorb glucose – Maintains normal glucose level.

Question 10.
Explain how hormones influence plant growth in the following situations?
• A seedling grows in complete darkness.
• A farmer sprays gibberellins on a crop
Answer:
• Seedling in darkness: Auxin distributes evenly – Stem elongates abnormally – Seedling becomes pale and weak.
• Spraying gibberellins: Promotes stem elongation, breaks seed dormancy, increases fruit size.

Biology Class 10 Chapter 4 Notes Kerala Syllabus Chemoreception in Organisms

Question 1.
How was the discovery of auxin, that influence the growth of plants?
Answer:
F. W. Went, a botanist from Holland cut the coleoptile of the oats plant while studying the growth of plants,and kept it in a jelly like substance called agar. After a few hours, he removed the coleoptile from agar and cut the agar into small pieces. When he kept the agar block on the cut end of coleoptile, he observed that the tip of the plant showed growth towards the upper side. When it was placed on one side, the plant bent and grew towards the opposite side. It was later discovered that the chemical substance diffused into the agar from the coleoptile was responsible for the growth of the plant tip. It was later named auxin.

Question 2.
What are known as plant hormones?
Answer:
Later, many such substances that influence the growth of plants were discovered by scientists. They are known as plant hormones.

Question 3.
What all things understood about hormones?
Answer:

• Hormones are chemical substances.
• Hormones control and coordinate various functions in the body.
• Hormones are produced in small amounts.

Answers to the indicators on page 113 of the textbook
Question 4.
Target cells
Answer:
All hormones do not function in all cells. A cell in which a hormone acts is called the target cell.

Question 5.
Relationship between hormones and target cells
Answer:
A cell in which a hormone acts is called the target cell. The target cell of each hormone has receptors suitable for that hormone. Receptors are seen in the cell membrane and within the cells. Hormones combine with their receptors to form a hormone receptor complex. This complex controls activities inside the cell.

Question 6.
Transport of plant and animal hormones
Answer:
In animals, the hormones that are produced by endocrine glands reach the target cells through blood. Plant hormones are produced at the tip of the shoot or root, in seeds or in sprouting leaves. They reach the target cells via cell-to-cell transport or through xylem and phloem.

Question 7.
How does auxin help in the bending and growth of the plant?
Answer:

Auxins have a tendency to stay away from light. When sunlight falls vertically on the stem of a plant, auxin is distributed uniformly to all sides of the stem. When light falls on the stem from only one direction, auxin moves to the opposite side of the stem. There, auxin combines with hormone receptors in the cells to form a hormone receptor complex and as a result, changes occur in cellular activities. The cells on the shaded side elongate and the part where cell elongation occurs bends towards the opposite side.

Question 8.
Completed worksheet 4.1 on page 115

Answer:

Question 9.
Write about the name and use of synthetic plant hormones used in the agricultural sector.
Answer:
Natural plant hormones are also artificially synthesized after a detailed study of their chemical struture and are being widely used in the field of agriculture.

Synthetic auxins – Used to induce root formation in stem cuttings. Also used as a weedicide (2, 4 – D). Synthetic gibberellins – To increase the size of fruits in grapevines and to promote stem elongation in sugarcane.

Synthetic ethylene – In agricultural sector, ethylene is used to make fruits ripen uniformly for harvest at the same time. Ethylene is used to ripen bananas and tomatoes simultaneously.

The ideas related to debate on the topic – the health issues and environmental problems caused by synthetic plant hormones.

The use of synthetic plant hormones causes diseases, allergies, and genetic problems.
Environmental issues: The spread of synthetic hormones to other habitats, affecting soil and water, and im-pacting other organisms.

Answers to the indicators on page 113 of the textbook
Question 10.
Photoperiodism
Answer:
Flowering is closely related to the length of day and night. This response of plants to the photoperiod is known as photoperiodism. Based on this, plants regulate flowering time, pollination, and seed formation.

Question 11.
Phytochrome
Answer:
Phytochrome, alight-sensitive pigment, plays a major role inphotoperiodism. Phytochrome is synthesized in the fully developed leaves at the shoot apex.

Question 12.
Flowering
Answer:
Phytochrome is synthesized in the fully developed leaves at the shoot apex. These leaves, perceive the length of day and night through phytochrome and transmit a signal to the shoot apical meristem to induce flowering. As a result of this, genes that control flowering is stimulated.

Question 13.
Position of the gland
Answer:
The thyroid gland is located in the front of a person’s neck, just below the larynx.

Question 14.
Cells
Answer:
There are two types of cells in the thyroid gland: Follicular cellsand Parafollicular cells.

Question 15.
Hormone
Answer:
Follicular cells produce the hormone thyroxine, while parafollicular cells produce the hormone calcitonin.

Question 16.
Function
Answer:
Thyroxine – Controls metabolism and body temperature. Development of brain in newborn babies and children, Helps to maintain the health of the heart, skin, reproductive system, etc.

Question 17.
Collect more information about the various forms of thyroxine, such as T3 and T4.
Answer:
The thyroid gland produces two main hormones: T4 (Thyroxine) and T3 (Triiodothyronine). T4 has 4 iodine atoms, is made in larger amounts, less active, and mainly acts as a storage form. T3 has 3 iodine atoms, is made in smaller amounts, but is more active and directly controls metabolism. T4 converts into T3 in the body for actual use. Both are important for growth, metabolism, and body temperature.

Question 18.
What are the diseases caused by the fluctuations in thyroxine production and the malfunction of the gland?
Answer:
Hyperthyroidism, Hypothyroidism, Goitre

Question 19.
Write the cause and symptoms of Hyperthyroidism.
Answer:
Cause – Excessive secretion of thyroxine.
Symptoms – Increase in the rate of metabolism, weight loss, heart beat increases, excessive sweating, anxiety

Question 20.
Write the cause and symptoms of Hypothyroidism.
Answer:
Cause – Reduced secretion of thyroxine
Symptoms- Metabolism decreases, body weight increases, heart rate slows down, fatigue, intolerance to cold.

Question 21.
Write the cause and symptoms of Goitre.
Answer:
Cause – Various disorders of thyroid gland, deficiency of iodine.
Symptoms – Swelling in the neck region, difficulty in swallowing

Answers to the indicators on page 119 of the textbook
Question 22.
Normal level of calcium
Answer:
The normal level of calcium in blood is 9-11 mg/dL.

Question 23.
Action of Calcitonin
Answer:
When the level of calcium increases in blood – Thyroid gland produces Calcitonin.
Calcitonin – Inhibits the reabsorption of calcium and phosphate from blood. Decreases the absorption of calcium from blood. Inhibits the activity of mixing of calcium and phosphate from the bones.

Question 24.
Action of Parathormone
Answer:
When the level of calcium decreases in blood – Parathyroid gland produces Parathormone.

Parathormone – Accelerates the reabsorption of calcium and phosphate from blood. Accelerates the absorption of calcium from blood. Stimulates the activity of mixing of calcium and phosphate from the bone into the blood.

Question 25.
What is the normal level of glucose in the blood?
Answer:
The fasting blood glucose (FBS) level in healthy individuals typically ranges from 70 to 100 mg/ dL. The glucose level should be below 140 mg/ dL, two hours after having food(PPBS). If the average blood glucose level of three months measured using HbAlc test is below 5.7 %, it can be considered a normal glucose level.

Question 26.
What are the hormones that help regulate the level of glucose in the blood?
Answer:
The glucose level is regulated by the actions of insulin and glucagon.

Question 27.
Where are insulin and glucagon produced?
Answer:
If the level of glucose in the blood increases, insulin produced by the beta cells of the Islets of Langerhans in the pancreas regulates it.

If the level of glucose in the blood decreases, glucagon produced by the alpha cells of the Islets of Langerhans in the pancreas regulates it.

Answers to the indicators on page 121 of the textbook
Question 28.
Action of insulin
Answer:
If the amount of glucose in the blood increases, insulin produced by the beta cells of the pancreas regulates it.

Insulin – Speeds up the entry of glucose into cells. In the liver and muscle cells, glucose is converted into glycogen.

Question 29.
Action of glucagon
Answer:
If the amount of glucose in the blood decreases, glucagon produced by the alpha cells of the pancreas regulates it.

Glucagon – Helps in the formation of glucose from glycogen and amino acids with the help of the liver.

Question 30.
Completed table 4.4 on page 122 of the text book

Answer:

Answers to the indicators on page 123 of the textbook
Question 31.
Different type of diabetes
Answer:
Diabetes mellitus is a condition in which the level of glucose in blood rises above normal (FBS above 126mg/dL).
There are two types of diabetes- Type I and type II

Question 32.
Causes
Answer:
There are two types of diabetes- Type I and type II. Type II diabetes is a condition caused by factors such as variation in insulin production, lack, of dietary control, and decreased effectiveness of insulin. Type – 1 diabetes is the condition in which insulin production capacity is lost due to the destruction of beta cells.

Question 33.
Symptoms
Answer:
Excessive thirst, hunger, frequent urination, weight loss and fatigue are its symptoms.

Question 34.
Prepare a questionnaire based on the hints given below, conduct an interview with a doctor
Answer:

• What is retinopathy, and how does it affect the eyes of a diabetes patient?
• What is nephropathy, and why are the kidneys at risk in diabetes?
• Could you explain what neuropathy is and its common symptoms?
• What do you mean by resistance to insulin, and how does it lead to diabetes?
• What are some preventive treatments or lifestyle changes to control or avoid diabetes?
• How important are regular check-ups for people with diabetes?
• What advice would you give to teenagers to prevent diabetes in the future?

Question 35.
Report based on the interview
Answer:
The doctor explained that retinopathy affects the eyes and may lead to vision loss, while nephropathy damages the kidneys. Neuropathy affects the nerves, causing pain or numbness. He further explained that insulin resistance is when the body’s cells do not respond properly to insulin, which increases blood sugar levels. For preventive treatment, the doctor advised maintaining a healthy diet, regular exercise, avoiding junk food, and going for routine health check-ups. The doctor concluded by emphasizing that if healthy habits are adopted early in life, the chances of getting diabetes can be reduced. This interview helped us understand the seriousness of diabetes and the importance of prevention.

Question 36.
Why are hormones needed when the sympathetic system is able to control physical changes during emergencies?
Answer:
The sympathetic nervous system controls emergency situations by sending quick nerve signals, but its effect lasts only for a very short time. Hormones, on the other hand, are released into the blood and can circulate throughout the body. They make the response stronger and keep it active for a longer duration. Thus, hormones are needed along with the sympathetic system to ensure that the body’s emergency response is both quick and long-lasting.

Answers to the indicators on page 124 of the textbook
Question 37.
Position of the adrenal gland
Answer:
Above the kidneys

Question 38.
Parts
Answer:
Outer part cortex and inner part medulla

Question 39.
Hormones secreted by the medulla
Answer:
The inner part of the adrenal gland called medulla secretes two hormones namely epinephrine and norepinephrine.

Question 40.
The way to overcome an emergency
Answer:
These hormones prepare the body to deal with an emergency situation through a number of physiological changes such as an increased heart rate and blood pressure, increased blood glucose levels, increased blood flow to the heart and muscles, decreased blood flow to the skin and digestive organs, etc.

Question 41.
What are corticosteroids?
Answer:
The cortex of the adrenal gland produces various hormones that belong to the class of glucocorticoids, mineralocorticoids, and gonadocorticoids. They are generally known as corticosteroids.

Question 42.
What are the different types of corticosteroids?
Answer:
Cortisol, Aldosterone, Androgens

Question 43.
Completed table 4.5 in page 125 of the text book (The hormones produced by cortex and their functions)

Answer:

Question 44.
What are the functions of Melatonin?
Answer:
The pineal gland, located near the thalamus in the human brain, produces a hormone called melatonin. The variations in the secretion of this hormone influences sleep and wakefulness.

Question 45.
Why pineal gland is known as the biological clock?
Answer:
Melatonin plays a major role in controlling the activities that occur at regular intervals throughout the day. Therefore, pineal gland is known as the biological clock.

Question 46.
How we can promote quality sleep?
Answer:
Using a computer or mobile phone for a long time at night can lead to difficulty falling asleep, disrupt sleep and feeling sleepy during the day. The use of such devices should be completely avoided before sleeping. Melatonin is produced in the required quantity for the brain only under such conditions”, thereby promoting quality sleep.

Question 47.
Is darkness necessary for sleeping? Why?
Answer:
Darkness is necessary for sleep because it helps the brain release melatonin, the sleep hormone. Melatonin makes us feel sleepy and maintains the sleep-wake cycle. Too much light reduces melatonin, so people sleep better in darkness.

Question 48.
What is the role of thymus gland in the body’s immune system?
Answer:
The thymus gland, located behind the sternum, plays a majorrole in the body’s immune system. The hormone thymosin produced by thymus gland helps in the maturation of lymphocytes.

Question 49.
How can the hypothalamus be considered the master controller of the hormone production process?
Answer:
The functions of most endocrine glands are controlled by the hypothalamus. The pituitary gland is seen below the hypothalamus. The hypothalamus controls the functioning of other endocrine glands by regulating the production of tropic hormones secreted by the anterior lobe of the pituitary gland. Therefore, we can say that the hypothalamus can be considered as the master controller of the hormone production process.

Answers to the indicators on page 127 of the textbook
Question 50.
Parts of the pituitary gland
Answer:
Two parts – Anterior lobe, Posterior lobe

Question 51.
The lobes of the pituitary gland and their relationship with hypothalamus
Answer:
The neurosecretory cells of the hypothalamus are connected to the anterior lobe of the pituitary gland via the portal vein and to the posterior lobe of the pituitary gland via nerve fibres.

Question 52.
The hypothalamus hormone which reaches the anterior lobe and its function
Answer:
The neurosecretory cells of the hypothalamus are connected to the anterior lobe of the pituitary gland via the portal vein. Releasing hormone reaches the anterior lobe of the pituitary and stimulates the production of tropic hormones. Inhibitory hormones inhibit their production.

Question 53.
The hypothalamus hormone which reaches the posterior lobe and its function.
Answer:
Vasopressin and oxytocin, which are produced by the neurosecretory cells of the hypothalamus, are stored in the posterior lobe of the pituitary gland via nerve fibres. Vasopressin helps in the reabsorption of water in the kidneys. Oxytocin aids in milk secretion and the contraction of the smooth muscles of the uterus.

Question 54.
Pituitary hormones and their functions
Answer:
TSH – Stimulates Thyroid gland
ACTH – Stimulates Adrenal cortex
GTH – Stimulates the action of ovary and testes
Prolactin – Produces milk.
Somatotropin – Helps in body growth

Question 55.
Which hormone helps in growth?
Answer:
Growth hormone (somatotropin, GH) is a growth regulating hormone produced by the anterior lobe of the pituitary gland. This is a hormone that accelerates the process of cell division known as mitosis and increases cell size, leading to body growth.

Question 56.
What are the growth defects caused by variations in the production of somatotropin?
Answer:
The variations in somatotropin’s production cause growth disorders like Dwarfism, Gigantism, Acromegaly

Question 57.
Write the cause and symptoms of Dwarfism
Answer:
Dwarfism
Cause – The production of somatotropin decreases during the growth phase
Symptom – Stunted growth

Question 58.
Write the cause and symptoms of Gigantism.
Answer:
Gigantism
Cause – The production of somatotropin increases during the growth phase.
Symptom – Excessive body growth

Question 59.
Write the cause and symptoms of Acromegaly.
Answer:
Acromegaly
Cause – The production of somaotropin increases after growth phase.
Symptom – Excessive growth of body parts such as palms, foot and jaws.

Question 60.
How does the action of vasopressin affect the body during summer and winter?
Answer:
Vasopressin helps to maintain water balance in the body. Excessive heat and sweating during summer can lead to dehydration, which increases the production of vasopressin. It speeds up water reabsorption in the kidney. As a result, the production of urine decreases, and dehydration is prevented. During winter, since dehydration through sweating is reduced, the reabsorption of water from the kidneys also decreases.

Question 61.
Completed illustration 4.11 on page 129 of the text book
Answer:

Question 62.
Write about the hormones associated with reproduction and birth, and their functions.
Answer:
Testosterone – produced in testes. The activity of male sex organs. Sperm production. Controls secondary sexual characteristics.
Estrogen – produced in ovary – The activity of female sex organs. Production of ovum. Menstrual cycle. Control of secondary sexual characteristics
Progesterone – produced in ovary – Maintaining the foetus in the uterus. Menstrual cycle
Prolactin – Produces milk.
Oxytocin helps with milk secretion and the contraction of smooth muscles in the uterus.

Question 63.
What are pheromones?
Answer:
Pheromones are chemical substances that are secreted by organisms to their immediate surroundings to facilitate communication with the same species.

Question 64.
Write the different types of pheromones and their functions.
Answer:
Territorial Pheromone: Used to mark the boundaries of a habitat. An example of this is how mammals like dogs and cats use urination to indicate their presence and mark their territory.
Aggregation Pheromone: Helps ensure food availability. Ants use this type of pheromone.
Alarm Pheromone: Used to signal danger. Ants also use this pheromone.
Sexual Pheromone: Used to attract mates. Animals like rabbits and insects use this pheromone.

Question 65.
Do plants produce pheromones?
Answer:
Yes, plants produce pheromone-like chemicals, also called volatile substances. These help in communication and protection. For example, some plants release scents to attract insects for pollination, while others release warning chemicals when attacked by insects. These signals can make nearby plants prepare their own defense or repel herbivores. Thus, plants use pheromones to survive and interact with their surroundings.

Std 10 Biology Chapter 4 Notes – Extended Activities

Question 1.
Create an awareness poster, video, etc. on the prevention of diabetes through lifestyle changes.

Question 2.
Apply plant parts containing natural auxins on plants and observe their growth pattern. Conduct an experiment by cutting the tip of a plant and observing the effects on its growth.

Question 3.
Research and present the life stories of famous people who experienced growth-related disorders.
Answer:
Famous People and Their Hormonal Variations

1. Lionel Messi
A world-famous Argentine football player.
He was found to have a growth hormone deficiency as a child. He continued playing football after achieving normal growth through hormone therapy.
Today, he is considered one of the greatest football players of all time.

2. Warwick Davis
British actor.
He has a rare form of dwarfism. He became famous for his characters in films such as ‘Star Wars,’ Harry Potter,’ and Willow.’ He is an inspiration to many, proving that physical differences are not limitations to talent.

Question 4.
Maintain a one-month diet journal focusing on foods rich in calcium and their impact on bone health.
Answer:
Calcium and Bone Health: A One-Month Diet Plan
I included foods such as milk, curd, cheese, ragi, leafy vegetables, almond, and fish in my diet plan. Consuming calcium-rich food daily helps to keep the bones healthy and strong.

Question 5.
Research on how plant hormones are used in fruit ripening and present your findings as a report.
Answer:
Report
The main hormone involved in fruit ripening is Ethylene. Ethylene helps fruits like bananas, mangoes, and tomatoes to become soft, sweet, and gain color. Farmers use Ethylene or Ethylene-releasing chemicals to quickly ripen fruits for the market. This method helps the fruits to ripen uniformly and reduces wastage.

Chemoreception in Organisms Class 10 Notes

Chemoreception in Organisms Notes Pdf

• Different types of hormones are present in plants and animals.
• All hormones do not function in all cells. A cell in which a hormone acts is called the target cell.
• Hormones and receptors combine to form the hormone receptor complex. This complex regulates the activities inside the cell.
• The main plant hormones are Abscisic acid, Gibberellins, Cytokinins, Auxins, and Ethylene.
• Synthetic plant hormones are plant hormones produced artificially by understanding the chemical structure of naturally occurring plant hormones. Synthetic plant hormones are widely utilized in the agricultural secto
• The production of flowers is related to the length of the day and night. This response of plants is called photoperiodism. Based on this, plants regulate stages such as flowering time, pollination, and seed formation.
• The light-sensitive pigment phytochrome plays a maj or role in photoperiodism.
• The Thyroid gland is a gland that plays a major role in controlling metabolism, body growth, and development.
• There are two types of cells in the thyroid gland: follicular cells and parafollicular cells. Follicular cells produce the hormone Thyroxine, and parafollicular cells produce the hormone Calcitonin.
• Thyroxine – Controls metabolism and body temperature. Develops the brain in newborns and children. Maintains the health of the heart, skin, and reproductive system, etc.
• Calcitonin – Decreases the level of calcium in the blood.
• Disease conditions caused by fluctuations in Thyroxine production or malfunctioning of the gland are Hyperthyroidism, Hypothyroidism, and Goitre.
• The normal level of calcium in the blood is 9 – 11 mg / dL
• The blood calcium level is regulated by Calcitonin produced by the thyroid gland and Parathormone produced by the Parathyroid gland, which is situated on the posterior side of the thyroid gland.
• The level of Fasting Blood Glucose (FBS) in healthy individuals is 70-100 mg/dL.
• The disease condition in which the glucose level in the blood rises above the normal average is Diabetes Mellitus. Symptoms of diabetes include excessive thirst, hunger, frequent urination, weight loss, and fatigue.
• Type 2 diabetes is caused by factors such as fluctuations in insulin production, lack of dietary control, and decreased functional efficiency of insulin. Type 1 diabetes is a condition where the ability to produce insulin is” lost due to the destruction of beta cells.
• During emergency situations, along with the sympathetic system, certain hormones produced by the Adrenal gland, which is part of the endocrine system, also act.
• The Medulla, the inner part of the Adrenal gland, secretes the hormones Epinephrine and Nor-epinephrine.
• Epinephrine and Nor-epinephrine, along with the sympathetic system, prepare the body to face an emergency situation.
• The Cortex of the Adrenal gland produces various hormones belonging to the categories Glucocorticoids, Mineralocorticoids, and Gonadocorticoids. These are known as Corticosteroids.
• Cortisol, Aldosterone, and Androgens are different Corticosteroids.
• The Pineal Gland, situated near the thalamus in the brain, produces the hormone Melatonin. Fluctuations in Melatonin production affect daily sleep and wakefulness.
• The hormone Thymosin, produced by the Thymus gland, helps in the maturation of T-lymphocytes.
• The functions of most endocrine glands are controlled by the Hypothalamus. The Hypothalamus controls the function of other endocrine glands by regulating the production of trophic hormones produced by the anterior lobe of the pituitary gland.
• Releasing hormones and Inhibitory hormones, produced by the neurosecretory cells of the Hypothalamus, reach the anterior lobe of the pituitary.
• Releasing hormones reach the anterior lobe via the portal vein and stimulate the production of trophic hormones. Inhibitory hormones prevent their production.
• Vasopressin and Oxytocin, produced by the neurosecretory cells of the Hypothalamus, are stored in the posterior lobe of the pituitary gland via nerve fibers.
• TSH – Stimulates the Thyroid Gland.
• ACTH – Stimulates the Adrenal Cortex.
• GTH – Stimulates the function of the Ovary and Testis.
• Somatotropin – Helps in body growth.
• Prolactin – Produces breast milk.
• The growth hormone (Somatotropin, GH) produced by the anterior lobe of the pituitary gland controls growth. Somatotropin is the hormone that causes body growth by accelerating cell division and increasing cell size in most body cells.
• Fluctuations in Somatotropin production lead to growth disorders (Dwarfism, Gigantism, Acromegaly).
• Water balance in the body occurs through the action of the hormone Vasopressin or Anti-Diuretic Hormone (ADH), which is stored in the posterior part of the pituitary gland. ADH helps to maintain the water content in the body.
• Testosterone – Produced in the Testis. It regulates the function of male reproductive organs, sperm production, and secondary sexual characteristics.
• Estrogen – Produced in the Ovary. This hormone performs the regulation of female reproductive organ function, ovulation, menstrual cycle, and secondary sexual characteristics.
• Progesterone – Produced in the Ovary. This hormone helps to maihtain the embryo in the uterus and regulate the menstrual cycle.
• Pheromones are chemical substances secreted by organisms of the same species into the surroundings for communication. Pheromones have a volatile nature.
• Trail pheromone, Territorial pheromone, Aggregation pheromone, Alarm pheromone, and Sexual pheromone are different types of pheromones.

INTRODUCTION

Hormones and Life processes
Different types of hormones are present in plants and animals. All hormones do not function in all cells. A cell in which a hormone acts is called the target cell. The target cell of each hormone has receptors suitable for that hormone. Hormones combine with their receptors to form a hormone- receptor complex. This complex controls activities inside the cell.

Plant Hormones and their Functions
Plant hormones influence plant growth and other activities. Abscisic acid, Gibberellins, Cytokinins, Auxins, Ethylene are the major plant hormones. Natural plant hormones are also artificially synthesized after a detailed study of their chemical struture and are being widely used in the field of agriculture. These are synthetic plant hormones. Synthetic auxins, Synthetic Gibberelins, Synthetic ethylene are synthetic plant hormones widely used in the field of agriculture. Flowering is closely related to the length of day and night. This response of plants to the photoperiod is known as photoperiodism. Based on this, plants regulate flowering time, pollination, and seed formation.

Control of Metabolism
Thyroid gland plays a crucial role in regulating metabolism, body growth and development. Follicular cells in the thyroid gland produce the hormone thyroxine, while parafollicular cells produce the hormone calcitonin. Thyroxine controls metabolism and body temperature, development of brain in newborn babies and children and helps to maintain the health of the heart, skin, reproductive system, etc.

Regulation of calcium and glucose in blood
The normal level of calcium in blood is 9 – 11 mg/dL.The level of calcium is maintained at the proper level by the combined action of calcitonin produced by the thyroid gland and parathormone produced by the parathyroid gland located behind the thyroid gland.

The fasting blood glucose (FBS) level in healthy individuals typically ranges from 70 to 100 mg/ dL.When the glucose level in the blood increases, the beta cells in the pancreas produce insulin, which regulates the glu¬cose level in the blood. If the glucose level in the blood decreases, the alpha cells in the pancreas produce glu-cagon, which regulates the glucose level in the blood. Diabetes mellitus is a condition in which the level of glucose in blood rises above normal. Diabetes appears in two types: type 1 and type 2.

Overcoming emergency situations
In emergency situations, epinephrine and norepinephrine produced by the adrenal gland, which is part of the endocrine system, work in conjunction with the sympathetic nervous system. The cortex of the adrenal gland produces various hormones that are categorized as glucocorticoids, mineralocorticoids, and gonadocorticoids. These are known as corticosteroids.Cortisol, aldosterone, and androgen are various corticosteroids.

The pineal gland, located near the thalamus in the brain, produces the hormone melatonin. Melatonin plays a major role in regulating the body’s 24-hour rhythmic activities. Because of thisf the pineal gland is known as the biological clock.

The thymus gland, located behind the sternum, plays a major role in the body’s immune system. The hormone thymosin produced,by thymus gland helps in the maturation of T lymphocytes.

Hypothalamus and Pituitary : Master Control System
The hypothalamus controls the function of other endocrine glands by regulating the production of tropic hormones from the anterior lobe of the pituitary gland. The releasing hormones and inhibiting hormones produced by the neurosecretory cells in the hypothalamus reach the anterior lobe of the pituitary gland.

Vasopressin and oxytocin, produced by the neurosecretory cells in the hypothalamus, are stored in the posterior lobe of the pituitary gland via nerve fibers. The hormones produced by the pituitary gland are: TSH, ACTH, GTH, Somatotropin, Prolactin.

Growth hormone (somatotropin, GH) is a growth regulating hormone produced by the anterior lobe of the pituitary gland. This is a hormone that accelerates the process of cell division known as mitosis and increases cell size, leading to body growth. The variations in its production cause growth disorders like dwarfism, gigantism, and acromegaly.

Water balance in the body is maintained by the action of vasopressin, also known as the Antidiuretic Honnone (ADH), which is stored in the posterior part of the pituitary gland. ADH helps to maintain the water content in the body.

Communication can also be like this
Pheromones are chemical substances that are secreted by organisms to their immediate surroundings to facilitate communication with the same species. These volatile substances perform various functions. The reason ants move in a line is due to trail pheromones, which help them determine the path.

HORMONES AND LIFE PROCESSES
Finding of Auxins

• F. W. Went, a botanist from Holland studied the growth of plants,
• Later, many such substances that influence the growth of plants were discovered by scientists. They are known as plant hormones.

Hormones and Life processes

• Different types of hormones are present in plants and animals.
• All hormones do not function in all cells. A cell in which a hormone acts is called the target cell.
• The target cell of each hormone has receptors suitable for that hormone. Receptors are seen in the cell membrane and within the cells.
• Hormones combine with their receptors to form a hormone- receptor complex. This, complex controls activities inside the cell.
• In animals, the hormones that are produced by endocrine glands reach the target cells through blood.
• Plant hormones are produced at the tip of the shoot or root, in seeds or in sprouting leaves. They reach the target cells via cell-to-cell transport or through xylein and phloem.

side, the plant bent and grew towards the opposite side. It was later discovered that the chemical substance diffused into the agar from the coleoptile was responsible for the growth of the plant tip. It was later named auxin.

PLANT HORMONES AND THEIR FUNCTIONS
Plant Hormones

• Abscisic acid – Maintains the dormancy of seeds until favourable conditions arise, inhibits the growth of plant parts and enables them to tide over unfavourable conditions. It also promotes abscission of mature leaves and fruits.
• Gibberellins – Break seed dormancy, stimulate cell division in both stems and roots, influence the growth of fruits and seeds.
• Cytokinins – Stimulate cell division and cell differentiation in germinating seeds, stimulate the growth of lateral buds delay senescence and retains the green colour of leaves, stimulate cell division in both stems and roots, promote the transport of nutrients to growing regions.
• Auxins – Increase the length of the stem, inhibit lateral bud growth, and regulate tropic movements, stimulate the formation of flowers and fruits.
• Ethylene plays a role in the degradation of chlorophyll, proteins, and nucleic acids, leading to the ageing of leaves and flowers and ripening of fruits.

Synthetic Plant Hormones

• Synthetic Plant Hormones – Artificially synthesized after a detailed study of the chemical struture of natural hormones.
• Synthetic plant hormones are being widely used in, the field, of agriculture.
• Synthetic auxins – Used to induce root formation in, stem cuttings. Also used as a weedicide (2, 4 – D).
• Synthetic gibberellins – To increase the size of fruits in grapevines and to promote stem elongation in sugarcane.
• Synthetic ethylene – In agricultural sector, ethylene is used to make fruits ripen uniformly for harvest at the same time. Ethylene is used to ripen bananas and tomatoes simultaneously.
• Flowering is closely related to the length of day and night. This response of plants to the photoperiod is known as photoperiodism. Based on this, plants regulate flowering time, pollination, and seed formation.
• Phytochrome, a light-sensitive pigment, plays a major role in photoperiodism.
• Phytochrome is synthesized in the fully developed leaves at the shoot apex. These leaves, perceive the length of day and night through phytochrome and transmit a signal to the shoot apical meristem to induce flowering. As a result of this, genes that control flowering is stimulated.

CONTROL OF METABILISM

• Thyroid gland plays a crucial role in regulating metabolism, body growth and development.
• There are two types of cells in the thyroid gland: Follicular cellsand Parafollicular cells.
• Follicular cells produce the hormone thyroxine, while parafollicular cells produce the hormone calcitonin.
• Thyroxine – Controls metabolism and body temperature. Development of brain in newborn babies and children, Helps to maintain the health of the heart, skin, reproductive system, etc.
• Calcitonin – Reduces the level of calcium in blood.
• Fluctuation in the production of thyroxine and malfunctioning of the gland can lead to disease conditions like Hyperthyroidism, Hypothyroidism, Goitre.

REGULATION OF CALCIUM AND GLUCOSE IN BLOOD
Regulation of calcium in blood

• The normal level of calcium in blood is 9 – 11 mg/dL
• The level of calcium in blood is maintained at the proper level by the combined action of calcitonin produced by the thyroid gland and parathormone produced by the parathyroid gland located behind the thyroid gland.
• When the level of calcium decreases in blood – Parathyroid gland produces Parathormone.
• When the level of calcium increases in blood – Thyroid gland produces Calcitonin.
• Parathormone – Accelerates the reabsorption of calcium and phosphate from blood. Accelerates the absorption of calcium from blood. Stimulates the activity of mixing of calcium and phosphate from the bone into the blood.
• Calcitonin – Inhibits the reabsorption of calcium and phosphate from blood. Decreases the absorption of calcium from blood. Inhibits the activity of mixing of calcium and phosphate from the bones into the blood.

Regulation of glucose in blood

• The fasting blood glucose (FBS) level in healthy individuals typically ranges from 70 to 100 mg/ dL.
• The glucose level should be below 140 mg/ dL, two hours after having food(PPBS).
• If the average blood glucose level of three months measured using HbAlc test is below 5.7 %, it can be considered a normal glucose level.
• The pancreas is the gland that plays a key role in regulating the glucose level in the blood.
• A group of cells in the pancreas that functions in relation to hormone production is called the Islets of Langerhans. There are two types of cells in it: Alpha cells and Beta cells. Alpha cells produce the hormone glucagon and beta cells produce the hormone insulin.
• Blood glucose levels are regulated by the actions of insulin and glucagon.
• If the amount of glucose in the blood increases, insulin produced by the beta cells of the pancreas regulates it.
• If the amount of glucose in the blood decreases, glucagon produced by the alpha cells of the pancreas regulates it.
• Insulin – Speeds up the entry of glucose into cells. In the liver and muscle cells, glucose is converted into glycogen.
• Glucagon – Helps in the formation of glucose from glycogen and amino acids with the help of the liver.
• Diabetes mellitus is a condition in which the level of glucose in blood rises above normal (FBS above 126mg/dL).
• Excessive thirst, hunger, frequent urination, weight loss and fatigue are its symptoms.
• There are two types of diabetes- Type I and type II
• Type II diabetes is a condition caused by factors such as variation in insulin production, lack of dietary control, and decreased effectiveness of insulin.
• Type – 1 diabetes is the condition in which insulin production capacity is lost due to the destruction of beta cells.

OVERCOMING EMERGENCY SITUATIONS
Adrenal gland – Structure, Function

• Certain hormones produced by the adrenal gland, which is part of the endocrine system, also work in conjunction with the sympathetic nervous system during emergencies.
• The inner part of the adrenal gland called medulla secretes two hormones namely epinephrine and norepinephrine.
• Epinephrine and norepinephrine prepare the body to deal with an emergency situation through a number of physiological changes such as an increased heart rate and blood pressure, increased blood glucose levels, increased blood flow to the heart and muscles, decreased blood flow to the skin and digestive organs, etc
• The cortex of the adrenal gland produces various hormones that belong to the class of glucocorticoids, mineralocorticoids, and gonadocorticoids. They are generally known as corticosteroids.
• Cortisol, aldosterone, and androgens are various corticosteroids.
• Cortisol – Maintains glucose homeostasis, Suppresses the Immune responses, Resists inflammation and allergy of the body.
• Aldosterone – Helps in maintaining equilibrium of minerals in the body. Regulates blood pressure.
• Androgens, – Controls sexual development and sexual behaviour.

Sleep and Awakening

• The pineal gland, located near the thalamus in the human brain, produces a hormone called melatonin.
• The variations in the secretion of this hormone influences sleep and wakefulness.
• Melatonin plays a major role in controlling the activities that occur at regular intervals throughout the day. Therefore, pineal gland is known as the biological clock.

Behind immunity

• The thymus gland, located behind the sternum, plays a major role in the body’s immune system.
• The hormone thymosin produced by thymus gland helps in the maturation of lymphocytes.

HYPOTHALAMUS AND PITUITARY: MASTER CONTROL SYSTEM
Hypothalamus and Pituitary

• The functions of most endocrine glands are controlled by the hypothalamus.
• The pituitary gland is seen below the hypothalamus.
• The hypothalamus controls the functioning of other endocrine glands by regulating the production of tropic hormones secreted by the anterior lobe of the pituitary gland. Therefore, we can say that the hypothalamus can be considered as the master controller of the hormone production process.
• Releasing hormones and inhibiting hormones, which are produced by the neurosecretory cells of the hypothalamus, reach the anterior lobe of the pituitary gland.
• Releasing hormone reaches the anterior lobe of the pituitary and stimulates the production of tropic hormones. Inhibitory hormones inhibit their production.
• Vasopressin and oxytocin, which are produced by the neurosecretory cells of the hypothalamus, are stored in the posterior lobe of the pituitary gland via nerve fibers.
• Vasopressin reabsorbs water in the kidneys.
• Oxytocin helps with milk secretion and the contrac-tion of smooth muscles in the uterus.
• TSH – Stimulates Thyroid gland
• ACTH – Stimulates Adrenal cortex
• GTH – Stimulates the action of ovary and testes
• Prolactin – Produces milk.
• Somatotropin – Helps in body growth

Behind growth

• Growth hormone (somatotropin, GH) is a growth regulating hormone produced by the anterior lobe of the pituitary gland.
• Somatotropin is a hormone that accelerates the pro-cess of cell division known as mitosis and increases cell size, leading to body growth.
• The variations in somatotropin’s production cause growth disorders (Dwarfism, Gigantism, Acromegaly)
• Dwarfism – Cause – The production of somatotropin decreases during the growth phase. Symptom – Stunted growth
• Gigantism – Cause-The production of somatotropin increases during the growth phase. Symptom – Excessive body growth
• Acromegaly – Cause – The production of somaotropin increases after growth phase. Symptom – Excessive growth of body parts such as palms, foot and jaws.

Water balance

• Water balance is maintained by the action of a hormone called vasopressin or antidiuretic hormone (ADH), which is stored in the posterior lobe of the pituitary gland.
• Vasopressin helps to maintain water balance in the body.
• Excessive heat and sweating dining summer can lead to dehydration, which increases the production of vasopressin. It speeds up water reabsorption in the kidney. As a result, the production of urine decreases, and dehydration is prevented.
• During winter, since dehydration through sweating is reduced; the reabsorption of water from the kidneys also decreases.

Reproductive hormones

• Testosterone – produced in testes. The activity of male sex organs. Sperm production. Controls sec-ondary sexual characteristics.
• Estrogen – produced in ovary – The activity of female sex organs. Production of ovum. Menstrual cycle. Control of secondary sexual characteristics
• Progesterone – produced in ovary – Maintaining the foetus in the uterus. Menstrual cycle

COMMUNICATION CAN ALSO BE LIKE THIS
Pheromones

• Pheromones are chemical substances that are secreted by organisms to their immediate surroundings to facilitate communication with the same species.
• Pheromones have a volatile nature.
• The reason why ants travel in a line is due to trail pheromones, which help them determine the path of travel.
• Territorial Pheromone: Used to mark the boundaries of a habitat. An example of this is how mammals like dogs and cats use urination to indicate their presence and mark their territory.
• Aggregation Pheromone: Helps ensure food availability. Ants use this type of pheromone.
• Alarm Pheromone: Used to signal danger. Ants also use this pheromone.
• Sexual Pheromone: Used to attract mates. Animals like rabbits and insects use this pheromone.

Students rely on Class 10 Chemistry Notes Kerala Syllabus Chapter 7 Important Questions with Answers Some Compounds of Industrial to help self-study at home.

SSLC Chemistry Chapter 7 Important Questions Kerala Syllabus

Some Compounds of Industrial Class 10 Important Questions

Question 1.
Liquefied ammonia is known as ………………….
Answer:
Liquid ammonia

Question 2.
The Industrial preparation of Ammonia is known as ………………………….
a) Haber process
b) Contact process
c) Ostwald process
d) Bosch process
Answer:
a) Haber process

Question 3.
In which one of the following reversible reactions, the change in pressure does not influence the equilibrium?
i. N₂(g) + 3H₂(g) \(\text { ⇌ }\) 2NH₃(g)
ii. N₂(g) + O₂(g) \(\text { ⇌ }\) 2NO (g)
iii. 2NO(g) + O₂(g) \(\text { ⇌ }\) 2NO₂(g)
Answer:
N₂(g) + O₂(g) \(\text { ⇌ }\) 2NO (g)
There is no change in the number of moles of reactants and products.

Question 4.
Write the name of the catalyst used in the industrial production of sulphuric acid.
a) Vanadium pentoxide (V₂O₅)
b) Platinum (Pt)
c) Iron oxide (Fe₂O₃ )
d) Manganese oxide (MnO₂)
Answer:
a) Vanadium pentoxide (V₂O₅)

Question 5.
Which industrial process is used to manufacture sulphuric acid (H₂SO₄)?
A. Contact Process
B. Ostwald Process
C. Deacon Process
D. Haber-Bosch Process
Answer:
A. Contact Process

Question 6.
Match the following.

Choose the correct answer from the options given below.

Answer:
D. (a) – (iv), (b) – (iii), (c) – (ii), (d) – (i)

Question 7.
Statement 1: Nitrogen, Phosphorous and potassium are the three elements that plants need in large quantities. They are called as primary nutrients.
Statement 2: Elements like Iron and manganese are needed by plants only in very small amounts.
Which of the following is correct regarding the above statements?
A. Both statements are correct
B. Both statements are not correct
C. Only statement 1 is correct
D. Only statement 2 is correct
Answer:
A. Both statements are correct

Question 8.
How do the following conditions affect a reversible reaction?
i. More reactants are added.
ii. Products are removed.
Answer:
i. The rate of forward reaction increases
ii. Rate of forward reaction increases

Question 9.
H_2(g) + I_2(g) \(\text { ⇌ }\) 2HI_(g)
a) What is the total number of moles of reactants and products in the above reaction?
b) What is the effect of pressure in this reversible reaction? Explain.
Answer:
a) No. of moles of reactant = 2
No. of moles of product = 2

b) In a reversible reaction, if there is no change in the number of moles of reactants and products in the gaseous state, pressure will have no effect on the chemical equilibrium.

Question 10.
The flow chart of the industrial preparation of sulphuric acid is given. Complete it.

Answer:
(a) SO₂ (Sulphur dioxide)
(b) H₂S₂O₇ (Oleum)

Question 11.
A student dissolves ammonium chloride (NH₄Cl) in water and finds the solution is acidic. Explain this observation by answering the following questions.
(a) Identify the acid and base that react to form ammonium chloride (NH₄Cl).
(b) Which is stronger, the acid or the base?
Answer:
(a)The acid is Hydrochloric acid (HCl) and the base is Ammonium hydroxide (NH₄OH).
(b) The acid (hydrochloric acid) is stronger.

Question 12.
Graph of a reversible process,
N₂ + 3H₂ \(\text { ⇌ }\) 2NH₃ + heat is given. Analyze the graph and answer the following questions.

a) Identify the part of the graph that represents the forward reaction
[OA, BA, AC]
b) Identify the part of the graph which represents the equilibrium state
c) From the given statements, select the correct ones regarding chemical equilibrium.
i. Chemical equilibrium is static at the molecular level.
ii. Both reactants and products co-exist.
iii The rates of forward and backward reactions are equal.
iv. Chemical equilibrium is attained in an open system.
Answer:
a) BA
b) AC
c) (ii) Both reactants and products co-exist.
(iii) The rates of forward and backward reactions are equal

Question 13.
N₂(g) + 3H₂(g) \(\text { ⇌ }\) 2NH₃(g) + Heat
How do the following changes influence the amount of the product?
a) Temperature decreases.
b) Pressure increases.
c) Ammonia produced is removed continuously from the system.
Answer:
a) Amount of product increases
b) Amount of product increases
c) Amount of product increases

Question 14.
a) Which of the following chemicals are used to prepare ammonia (NH₃) in the laboratory?
[NaCl, Ca (OH)₂, CaCl₂, NH₄Cl]
b) Ammonia gas produced is passed through quick lime. Give a reason.
c) Which product is obtained when ammonia reacts with HCl?
Answer:
a) NH₄CI and Ca(OH)₂
b) To remove moisture content.
Quick lime is used as a drying agent.
c) NH₃ + HCl → NH₄Cl

Question 15.
A few drops of cone. H₂SO₄ are added to blue coloured copper sulphate crystals taken in a watch glass.
a) Write the observation.
b) Which property of sulphuric acid is exhibited here?
Answer:
a) The blue colour of CuSO₄ disappears
b) Dehydrating agent

Question 16.
represents an important stage in the Industrial preparation of Sulphuric acid.
a) By what name is the Industrial preparation of Sulphuric acid known as?
b) How do the following changes influence the forward reaction? :
i) More oxygen (O₂) is added
ii) Pressure is decreased
Answer:
a) Contact process
b) i) Increases the rate of forward reaction, and more product is formed.
ii) The rate of forward reaction decreases.

Question 17.
A reversible reaction at equilibrium is given.
2NO(g) + O₂(g) \(\text { ⇌ }\) 2NO₂(g) + Heat
Answer the following:
a) How does an increase in temperature influence the amount of products formed?
b) What change is to be made in pressure to get more product?
c) How does an increase in the concentration of oxygen influence the rate of the forward reaction?
d) What is the function of a catalyst in reversible reactions?
Answer:
a) Amount of product decreases
b) Increase pressure
c) Forward reaction increases
d) Helps to attain equilibrium more quickly

Question 18.
A reversible reaction at equilibrium is given.
2NO(g) + O₂(g) \(\text { ⇌ }\) 2NO₂(g)+Heat
a) Write the equation of the forward reaction.
b) How do the following changes affect the rate of forward reaction?
i. Adding more oxygen.
ii. Increasing pressure
c) What is the effect of a catalyst in a reversible reaction at equilibrium?
Answer:
a) 2NO(g) + O₂(g) → 2NO₂(g)
b) i. Increases,
ii. Increases
c) Catalyst does not affect reversible reactions at equilibrium

Question 19.
a) The industrial preparation of sulphuric acid is known as ___________ .
b) Which is the catalyst used in this process?
c) Take some sugar in a watch glass and add a few drops of concentrated sulphuric acid into it. What is your observation? Which chemical property of sulphuric acid is shown here?
d) Why concentrated sulphuric acid is not used as
drying agent in the preparation of Ammonia?
Answer:
a) Contact process
b) Vanadium pentoxide (V₂O₅)

c) Sugar is converted into a black substance. The dehydrating nature of sulphuric acid is shown here.

d) Concentrated sulphuric acid is not used as a drying agent in the preparation of ammonia because ammonia is basic and can react with concentrated Sulphuric acid, and then it will form ammonium sulphate.

Question 20.
The presence of various types of nutrients and the specific properties of a fertilizer are critical for
successful plant cultivation.
a) What are the three natural nutrients that plants absorb from air and water?
b) Explain the primary difference between primaiy and secondary nutrients.
c) State two essential qualities a fertilizer must have to be truly effective.
d) Why is a fertilizer that decomposes too quickly considered harmful to plants?
Answer:
a) The three natural nutrients plants absorb from air and wafer are carbon (C), hydrogen (H), and oxygen (O).

b) Primary nutrients are those needed by plants in large quantities, specifically nitrogen (N), phosphorus (P), and potassium (K). In contrast, secondary nutrients are required in smaller amounts and include calcium (Ca), magnesium (Mg), and sulphur (S).

c) Two essential qualities a fertilizer must have are:

• It should be soluble in water so that the nutrients can be absorbed by the plants.
• It should be stable and remain in the soil for a long time, providing a sustained release of nutrients.

d) A fertilizer that decomposes too quickly is harmful because it can cause a “fertilizer burn” that damages the plant’s roots. It also leads to nutrient leaching, which pollutes water, and provides only a brief nutrient boost rather than a steady supply necessary for healthy growth.

Question 21.
The chlor-alkali process is a significant industrial method for producing essential chemicals, including sodium hydroxide, through the electrolysis of brine.
a) What are the ions formed when sodium chloride dissolves in water, and what are their respective charges?
b) At which electrode does oxidation occur, and which ion is oxidised?
c) What is the function of the membrane used to separate the two chambers in the membrane cell?
d) List any two uses of sodium hydroxide.
Answer:
a) When sodium chloride dissolves in water, the
ions formed are sodium ions (Na⁺), which are positively charged, and chloride ions (Cl^–), which are negatively charged.

b) Oxidation occurs at the anode, where the chloride ion (Cl^–) is oxidised.

c) The membrane separates the two chambers and allows the passage of specific ions only, such as the Na⁺ ions moving from the left chamber to the right chamber.

d)

• For the preparation of soaps and detergents.
• For the purification of bauxite in the manufacture of aluminium.

Students rely on Class 10 Chemistry Notes Kerala Syllabus Chapter 6 Important Questions with Answers Metals to help self-study at home.

SSLC Chemistry Chapter 6 Important Questions Kerala Syllabus

Metals Class 10 Important Questions

Question 1.
Find the relation and fill in the blanks.
Copper pyrites : CuFeS₂
Zinc blende : …………………………
a) ZnS (Chemical formula)
b) Zinc (Ore)
c) Magnetite (Iron)
d) Leaching (Concentration method)
Answer:
a) ZnS (Chemical formula)

Question 2.
Bauxite is the ore of ………………………… metal
a) Iron
b) Aluminium
c) Zinc
d) Copper
Answer:
b) Aluminium

Question 3.
Find the relation and fill in the blanks
Bauxite : Leaching
Tinstone : ……………………….
Answer:
Magnetic separation (Method of concentration)

Question 4.
The ore of a metal is lighter than the impurities
Which method is suitable for its concentration?
a) Levigation
b) Magnetic separation
c) Froth floatation
d) Leaching
Answer:
c) Froth floatation

Question 5.
Which is the method used to concentrate Sulphide ores?
a) Magnetic separation
b) Leaching
c) Froth floatation
d) Levigation
Answer:
c) Froth floatation

Question 6.
The metal which is refined by distillation is _____________ .
(Sn, Cu, Hg, Pb)
Answer:
Hg

Question 7.
Statement 1: Roasting refers to heating the concentrated ore at a temperature below the melting point in the presence of air.
Statement 2: Calcination refers to heating the concentrated ore in limited quantities or absence of air at a temperature below the melting point. Which of the following options is true, regarding these statements?
A. Statements 1 and 2 are correct.
B. Statement 1 is correct, but 2 is not correct.
C. Statement 1 is not correct, but 2 is correct.
D. Statements 1 and 2 are not correct.
Answer:
A. Statements 1 and 2 are correct

Question 8.
Match the following

Choose the correct answer from the options given below.

Answer:
D. (a) – (ii), (b) – (iii), (c) – (i)

Question 9.
Molten iron obtained from the blast fiimace contains 4% carbon and other impurities. What is this known as?
(Pig iron, Cast Iron, Wrought Iron)
Answer:
Pig iron

Question 10.
What are ores? Give any one example.
Answer:
A mineral from which a metal is economically, easily and quickly extracted is called the ore of the metal – for example, aluminium – bauxite

Question 11.
Find out the odd one. Give reason.
Haematite, Bauxite, magnetite, Iron pyrites
Answer:
Bauxite – Ore of Aluminium. Others are minerals of Iron.

Question 12.
Choose the suitable method used in each of the following processes from the bracket.
[Liquation, Leaching, Froth floatation, Distillation]
a) Concentration of sulphide ores.
b) Refining of metals with low boiling points.
Answer:
a) Froth floatation
b) Distillation

Question 13.
a) Name a method of concentration of an ore in which impurities are heavier than the ore particles.
b) Select an ore which can be concentrated by using this method.
(Fe₃O₄, ZnCO₃, CaCO₃, ZnS)
Answer:
a) Froth floatation
b) ZnS

Question 14.
Concentrated Cu₂S is converted into oxide by roasting.
a) Write the process of roasting.
b) How impurities like sulphur and phosphorus are removed in this process?
Answer:
a) Roasting refers to heating the concentrated ore at a temperature below its melting point in the presence of air.
b) Sulphur and phosphorous are removed as their oxides.

Question 15.
Calcination and Roasting are two methods of conversion of concentrated ore into its oxide.
a) How does Roasting differ from Calcination?
b) Cu2S ore is converted into Cu₂O by ……………………..
process
Answer:
a) Roasting refers to heating the concentrated ore at a temperature below its melting point in the presence of air

b) Roasting

Question 16.
What is cathodic protection? Explain its underlying principle using an example involving two metals.
Answer:
Cathodic protection is a method used to prevent the corrosion of a metal by making it the cathode in an electrochemical cell. This process is a key form of galvanic corrosion prevention.

The principle is to connect the metal you want to protect (the cathode) to a more reactive metal (the anode), known as a sacrificial anode. The sacrificial anode will corrode preferentially, releasing electrons and protecting the cathode from rusting.

For example, when an iron pipe is buried underground, a block of a more reactive metal like ^ns magnesium is connected to it. The magnesium corrodes over time, acting as the anode and sacrificially protecting the iron pipe, which becomes the cathode.

Question 17.
Complete the table.

Answer:
a) Liquation
b) Low boiling point

Question 18.
Haematite is converted into iron by using the blast furnace.
a) Which are the substances fed into the blast furnace along with the ore of iron?
b) Which compound acts as the reducing agent in the blast furnace?
Answer:
a) Limestone, Coke
b) Carbon monoxide (CO)

Question 19.
Complete the table.

Answer:
a) Froth floatation
b) Levigation or Hydraulic washing
c) Leaching

Question 20.
Some metals and their refining methods are given. Find the appropriate pair.

Answer:

Question 21.
Match columns A, B and C suitably.

Answer:

Question 22.
Chemical equations of the reactions taking place in blast furnace during the industrial production of iron are given below.
i) C + O₂ → CO₂ + Heat
ii) CO₂ + C + Heat → 2CO
iii) Fe₂O₃ + 3CO → 2Fe + 3CO₂
iv) CaCO₃ → CaO + CO₂
v) CaO + SiO₂ → CaSiO₃
Answer the following questions.
a) Which compound acts as the reducing agent?
b) What is the function of CaO in the production of iron?
c) Which is the slag formed here?
Answer:
a) Carbon monoxide (CO)
b) Act as flux to remove Silica (SiO₂)
c) Calcium silicate (CaSiO₃)

Question 23.
Bauxite is the main ore of Aluminium.
a) Which method is used to concentrate bauxite?
b) Electricity is used as the reducing agent in the manufacture of Aluminium. Why?
c) Aluminium is obtained at which electrode during the electrolysis?
Answer:
a) Leaching
b) Aluminium is a highly reactive metal; thus strong reducing agent like electricity is used.
c) Cathode (Negative electrode)

Question 24.
Haematite is converted into iron by reactions taking place in the blast furnace.
a) Write the molecular formula of Haematite.
b) Which substance acts as the reducing agent in this process?
c) Molten iron is produced along with slag from the furnace. What is meant by slag?
d) Write the chemical equation that shows the formation of slag.
Answer:
a) Fe₂O₃
b) Carbon monoxide (CO)
c) Mixture of flux and gangue
d) CaO + SiO₃ → CaSiO₃

Question 25.
Zinc is an industrially important metal
a) Which is the ore of Zinc?
b) Write the name of the concentration method used for Zinc ore?
c) What is the process used in the conversion of zinc ore to zinc oxide after the concentration of the ore?
d) Write the name of the purification method used for Zinc.
Answer:
a) Zinc blende (ZnS)
b) Froth floatation
c) Roasting
d) Distillation

Question 26.
Aluminium is very useful in our daily life.
a) Which is the ore of aluminium?
a) Which is the solution used to concentrate aluminium ore?
b) Why is cryolite added to alumina during its electrolysis?
c) Write the equation of reduction of aluminium ion.
Answer:
a) Bauxite
b) Hot Concentrated NaOH solution.
c) Cryolite is added to alumina to reduce its melting point and increase its electrical conductivity.
d) Al³⁺ + 3e^– → Al

Students rely on SCERT Kerala Syllabus 10th Standard Chemistry Textbook Solutions and Class 10 Chemistry Chapter 6 Metals Notes Questions and Answers English Medium to help self-study at home.

SSLC Chemistry Chapter 6 Notes Questions and Answers Pdf Metals

SCERT Class 10 Chemistry Chapter 6 Metals Notes Pdf

SSLC Chemistry Chapter 6 Questions and Answers – Let Us Assess

Question 1.
Define the following and answer the given questions.
(1) Ore – What is the ore of aluminium?
(2) Roasting – Which type of ores are subjected to roasting?
(3) Reducing agent – What is the reducing agent used in the manufacture of aluminium?
(4) Flux – Which flux is used in the manufacture of copper? Why?
(5) Leaching – Which metal ore is leached with sodium cyanide?
Answer:
(1) Ore – Any mineral from which a metal can be extracted easily and economically is called an ore of that metal. Ore of Aluminium is Bauxite

(2) Roasting – Roasting refers to heating the concentrated ore at a temperature below the melting point in the presence of air. Sulphide ores are subjected to roasting,

(3) Reducing agent – The chemical species that helps reduction is the reducing agent. The reducing agent gets oxidised in a chemical reaction. The reducing agent used in the manufacture of aluminium is electricity.

(4) Flux – The ore may contain impurities that cannot be removed in the first stages of concentration methods. In order to remove these impurities, a substance is added during the metallurgical stage. This substance is known as Flux.
Flux used in the manufacture of Copper is Sand (SiO₂). The ore contains basic impurities such as iron oxide even after concentration. So acidic flux is used.

(5) Leaching – The powdered ore is mixed with a suitable solvent. The ore dissolves in it or undergoes a chemical reaction to become a solution. The gangue remains insoluble in it. It is then filtered out. This process is called leaching. Metal ore leached with sodium cyanide is gold and silver.

Question 2.
Find the relation and write the answer.
Zinc sulphide: Roasting
Calcium carbonate: …………(a)…………..
Magnetite: Magnetic separation
Bauxite: …………(b)…………..
Answer:
(a) Calcination
(b) Leaching

Question 3.
The chemical reaction that occurs when calcium carbonate is heated is given.
CaCO₃ CaO + CO₂
How is this chemical change of calcium carbonate utilised in the industrial preparation of iron?
Answer:
The chemical change of calcium carbonate (CaCO₃) is utilised in the industrial preparation of iron to remove impurities from the iron ore. The product of this reaction, calcium oxide (CaO), acts as a flux in the blast furnace.

When heated, calcium carbonate decomposes into calcium oxide and carbon dioxide. The calcium oxide then reacts with the silica (SiO₂) impurities present in the iron ore, forming a molten substance called slag (calcium silicate, CaSiO₂). This slag is less dense than the molten iron, allowing it to float on top and be easily separated, thus purifying the iron. The overall reaction for slag formation is:
CaO(s) + SiO₂(s) → CaSiO₂(l)

Question 4.
Following are two facts related to the manufacture of an industrially important metal.
• The ore is treated with hot NaOH solution.
• Electricity is used as the reducing agent to extract the metal.
(i) These facts are related to the production of which metal?
(ii) What is the reason for using electricity as the reducing agent?
(iii) Which substance is used as the electrolyte here?
(iv) Which gas is liberated at the anode?
Answer:
(i) Aluminium
(ii) Aluminium is a highly reactive and electropositive metal.
(iii) Molten cryolite (Na₃AlF₆)
(iv) Oxygen (O₂)

Question 5.
A portion of the periodic table is given.

(i) Which method given below is more possible for the production of gallium?
(Reduction using carbon, electrolysis)
(ii) If gallium chloride (GaCl₃) is electrolysed, what is the product formed at the cathode. Write the chemical equation.
(iii) Write the subshell electron configuration of the outermost shell of gallium.
Answer:
(i) Electrolysis. Gallium is a highly reactive metal.
(ii) Gallium metal.
Ga³⁺ + 3e^– → Ga
(iii) 4s² 4p¹ (Atomic number: 31)

Question 6.
Corrosion is a process by which iron is converted into its oxide. This is an oxidation reaction.
(i) What is oxidation?
(ii) Complete the following chemical equation.
….Fe + …O₂ → ..Fe₂O₃
(iii) Suggest two methods for preventing the corrosion of iron.
Answer:
(i) The process involving loss of electrons in a chemical reaction is called oxidation.
(ii) 4Fe + 3O₂ → 2Fe₂O₃
(iii)

1. Painting or coating
2. Galvanization

Question 7.
Alloys containing iron are given. Find a, b, c, d.

Answer:
(a) Fe, Al, Ni, CO
(b) For the manufacture of permanent magnets
(c) Stainless steel
(d) Also known as electrical steel. As it reduces electric loss, it is used in the core of electromagnetic instruments like motors, generators, transformers etc.

Chemistry Class 10 Chapter 6 Notes Kerala Syllabus Metals

Question 1.
Metals are used in many forms in different fields of our life. Try to find some of them and complete the table.

Answer:

Question 2.
Which metals are. mostly used in these situations? List them.
Answer:
Iron, Gold, Steel, Aluminium, Copper, Silver, Platinum
Metals are used in various fields because of some of their common properties.

Question 3.
What properties of metals are utilised in various fields?
Answer:

• Sonority
• Ductility
• High melting point
• Thermal conductivity
• Malleability
• Metallic lustre
• Hardness

Question 4.
The nature of ores is given. Complete the table using appropriate concentration methods.

Answer:

Question 5.
How are metals arranged in the reactivity series?
Decreasing order of reactivity / increasing order of reactivity
Answer:
Decreasing order of reactivity
Here are some metals in the reactivity series.

Mercury can be easily separated from its ores by controlled heating.

Metals with comparatively moderate reactivity like, are generally found as oxides, sulphides or carbonates.
Eg. ZnCO₃, ZnS, Fe₂O₃, SnO₂, PbS
There are two stages for the production of metal from them.

1. Conversion of concentrated ore to oxide
Two methods are commonly used for this.

(a) Calcination
Metal carbonates or hydroxides are converted to their oxides by a process called calcination.

Eg. CaCO₃(s) CaO(s) + CO₂(g)
ZnCO₃ (s) ZnO(s) + CO₂ (g)

(b) Roasting

Zinc sulphide and lead sulphide can be easily

c) converted into their oxides by this method
2ZnS(s) + 3₂ (g) 2ZnO(s) + 2S₂ (g)
2PbS (s) + 3₂ (g) 2PbO (s) + 2S₂ (g)

When the concentrated ore is subjected to roasting, the water content in them gets released as vapours. They become pure and moisture free oxide ores.

2. Reduction of oxide ore
The metal part of the ores is in the form of positive ions, and hence it can be extracted by a reduction process.

Question 6.
Note the process that separates zinc from zinc oxide.
ZnO + C → Zn + CO
Which is the reducing agent in this case?
Answer:
Carbon
Reducing agents such as coke (an allotrope of carbon) and carbon monoxide are used to extract moderately reactive metals such as iron, zinc and tin from their oxide ores. Carbon has a greater tendency to react with oxygen at high temperatures, so oxygen is easily removed from the ore.

Strong reducing agents are required to extract highly reactive metals such as sodium, potassium, calcium, magnesium and aluminium from their ores. Such metals are produced by electrolysis.

Question 7.
Complete the table regarding the manufacture of metals.

Answer:

Question 8.
The order of reactivity of some metals is given.
Al > Zn > Fe > Au
a) Which metal forms the most stable compound?
Answer:
Aluminium

b) Which metal is produced by electrolysis?
Answer:
Aluminium

c) Which metal can displace zinc from compounds of zinc? Why?
Answer:
Aluminium can displace Zinc from its compounds. A metal can displace another from a compound if it is more reactive. Since A1 is higher than zinc in the reactivity series, it can displace Zinc.

d) Which metal is found in the free state in nature?
Answer:
Gold (Least reactive one)

e) Which metal is produced by reduction using carbon?
Answer:
Zinc and Iron

Question 9.
Complete the table regarding the manufacture of iron.

Answer:

Iron is produced in steel towers, known as blast furnaces, which are 25 to 30 meters high. Its interior is lined with bricks (Refractory bricks) capable of withstanding high temperatures

The concentrated ore mixed with limestone ( CaCO₃) and coke (C) is fed from the top of the furnace via cup and cone arrangement. This mixture is called charge.

A blast of hot air is blown into the furnace from its bottom. As the charge descends from the top of the furnace, various chemical changes take place inside it. The coke combines with the oxygen in the air, when the blast of hot air flows from the bottom to the top of the blast furnace.
C + O₂ → CO₂ + heat
This is an exothermic reaction. Coke reacts with carbon dioxide to produce carbon monoxide. This is an endothermic reaction.
CO₂ + C+ heat → 2CO
The main chemical reaction taking place in the blast furnace is the reduction of iron ore using carbon monoxide.
Fe₂O₃ + 3CO → 2Fe + 3CO₂
Even though the iron ore fed into the furnace is in the most refined form, it may contain acidic impurities such as sand (silica SiO₂) that cannot be removed in the first stages of concentration methods. For this, a substance known as flux is added during the metallurgical stage. As the impurities are acidic in nature, a basic substance is used as the flux. The flux combines with gangue to form molten slag.
Gangue + Flux → Slag
When heated at high temperature, the limestone decomposes to calcium oxide (Quick lime). Calcium oxide produced in this reaction acts as flux.
The chemical changes of limestone inside the blast furnace.
CaCO₃ CaO(s) + CO₂(g)
Calcium oxide reacts with sand (SiO₂) to form calcium silicate (slag), which melts easily.

If the gangue in the ore is basic in nature, acidic flux should be used.

Since the molten slag is less dense, it floats on the molten iron. These are removed at regular intervals through a separate tube/ tap. This slag is used in the production of cement and in the construction of roads.

The molten iron obtained from the blast furnace contains 4% carbon and small amounts of other impurities such as manganese, silicon, phosphorus and sulphur. This is called pig iron.

If the percentage of impurity in it is reduced, the iron obtained can be cast as desired. It is called cast iron. It contains more than 2% carbon.

Wrought iron is a relatively pure form of iron, containing 0.02% – 0.05% carbon and small amounts of phosphorus, silicon, manganese, sulphur etc.

Question 10.
Prepare a list of different types of steels, their methods of manufacture and use. ICT can be utilised.
Answer:

• Tool Steel: Contains elements like tungsten, molybdenum, and cobalt to increase hardness, heat resistance, and wear resistance. It is used for tools, dies, and cutting instruments.
• Structural Steel: Used in construction and contains manganese to improve strength. It is used in buildings, bridges, and other large structures.

Methods of Manufacture
The primary method for producing steel involves the following steps:

1. Blast Furnace: Iron ore is melted in a blast furnace to produce pig iron.
2. Steel Making: The pig iron is then processed in a Basic Oxygen Furnace (BOF) or an Electric Arc Furnace (EAF) to reduce carbon content and add alloying elements.
3. Casting: The molten steel is cast into various shapes, such as slabs, blooms, or billets.
4. Finishing: The cast steel is then rolled, shaped, and heat-treated to achieve the desired properties.

Alloy steel
The use of metals in their pure form is relatively less. Most of the metals are converted into alloys to be used for various purposes in daily life.

Question 11.
List the alloys familiar to you.
Answer:
Brass, Bronze, Solder, Amalgam, Duralumin
Alloys are mixtures of two or more metals. Nonmetals like carbon, nitrogen and phosphorus are also used for the production of alloys.

Question 12.
What are the constituents of steel?
Answer:
Iron, Chromium, Nickel, Carbon
Alloy steels are made by adding other metals to steel. Their properties are different from those of steel.
Some important alloy steels:

Question 13.
Expand the list by finding more alloys, their constituents and uses.
Answer:

Question 14.
Complete the table regarding the production of zinc.

Answer:

Question 15.
What are the processes used in the conversion of zinc ore to zinc oxide after the concentration of ore?
Answer:
Roasting. Zinc sulphide can be easily converted into their oxides by this method.
2ZnS (s) + 3O₂(g) 2ZnO(s) + 2SO₂ (g)

When the concentrated ore is subjected to roasting, the water content in them gets released as vapours. They become pure and moisture free oxide ores.

Coke is mixed with the zinc oxide obtained after these processes.

This mixture is put into a furnace similar to a blast furnace. At high temperature in the furnace, the coke reduces zinc oxide to zinc.

ZnO (s) + C (s)Zn(s) + CO (g)
Zinc has comparatively low boiling point (907°C) and hence it vapourises at high temperature and comes out. It is immediately cooled to liquid form.

Question 16.
You are familiar with the purification process of zinc. What is it known as?
Answer:
Distillation
Brass is an important alloy containing zinc.

Question 17.
Prepare a note on the production of zinc and its use. Record it in the science diary.
Answer:
Production and Use of Zinc
Zinc is primarily produced from the mineral sphalerite through a process that involves roasting, followed by either electrolysis or smelting. Its main use is for galvanizing to protect steel and iron from rust. It is also used in alloys like brass, in die-casting, and for batteries.

Question 18.
What method of concentration is suitable for these sulphide ores?
Answer:
Froth floatation

Question 19.
The ore contains basic impurities such as iron oxide even after concentration. What type of flux is suitable to remove it? (Acidic / Basic)
Answer:
Acidic flux
Sand (SiO₂) having acidic nature is added to the ore and heated to form cuprous sulphide (Cu₂S) of maximum purity. It is partially converted to cuprous oxide (Cu₂O) when heated under controlled flow of air. The cuprous oxide converts the remaining cuprous sulphide into copper.

Note that no reducing agent is added here. Molten copper is cooled in moulds. The copper lumps thus obtained are called blister copper. The sulphur dioxide gas produced during the production of copper is released when the metal condenses. As a result blisters are formed and they appear as such on the surface of copper lumps.

Question 20.
Brass and bronze are important alloys that contain copper. List the constituent metals in them.
Answer:
Brass is an alloy of copper and zinc. Bronze is traditionally an alloy of copper and tin.

Purification of Copper
The method of refining copper is electrolytic refining. Copper used for electrical purposes should be 99.99% pure. A high quality product is obtained through electrolytic refining. The diagram of refining of copper is given.

Question 21.
Observe the diagram and complete the table.

Answer:

Question 22.
Prepare a note on the process involved in the purification of copper and record it in the science diary.
Answer:
Copper is purified using electrolytic refining. Impure copper acts as the anode (positive electrode) and pure copper as the cathode (negative electrode). Both are placed in a copper sulphate solution. When electricity is applied, copper from the anode dissolves and is deposited onto the cathode, leaving impurities behind.

Question 23.
What reaction takes place at the cathode?
Answer:
Al³⁺ + 3e^– → Al

Question 24.
What reaction takes place at the anode?
Answer:
2O^2- → O₂(g) + 2e^–

Question 25.
Which gas is liberated at the anode?
Answer:
Oxygen

Question 26.
In the electrolytic cell, the positively charged carbon rods are replaced periodically. What is the reason?
Answer:
The oxygen produced at the anode will cause the carbon rods to oxidise into carbon dioxide. As a result, the size of the anode rod decreases. So, Carbon rods need to be replaced periodically.

Question 27.
Complete the – Table related to the electrolysis of alumina.

Answer:

Duralumin and alnico are important alloys which contain aluminium. The constituents of alnico are Fe, Al, Ni, CO etc. Alnico is used for making permanent magnets.

Question 28.
What are the factors influencing the corrosion of iron?
Answer:

• Presence of Water and Oxygen
• Presence of Electrolytes
• pH of the Environment
• Temperature

The metals occupying higher positions in the reactivity series readily corrode upon contact with atmospheric air. The rate of corrosion decreases as we move down. Metals higher up the reactivity series are more electropositive, meaning they have a greater tendency to lose electrons and form positive ions. Corrosion, or oxidation, is the process where a metal loses electrons. Therefore, more reactive metals readily lose electrons to elements in the atmosphere, like oxygen and water, causing them to corrode faster than less reactive metals.

Even though aluminium is a metal at the top of the reactivity series, it resists corrosion to some extent. Aluminium’s corrosion resistance stems from its immediate reaction with atmospheric oxygen to form a thin, durable, and non-porous layer of aluminium oxide (Al₂O₃) on its surface. This protective layer acts as a barrier, preventing further oxidation and corrosion of the metal beneath. The oxide coatings on metals such as aluminium, zinc and tin are thin and nonporous and therefore protect the metal from further corrosion.

The corrosion of iron differ from this, because the hydrated iron oxide (rust) that forms on the surface of iron is porous and powdery. So this process of corrosion continues until the metal is destroyed.

The factors given below influence the corrosion of metals.?

• Nature of the metal
• Moisture in which gases or salts are dissolved
• Contact with other metals

Question 29.
Let us do an experiment.

Prepare a very dilute solution of sodium chloride in two large test tubes. Place iron nails, one tightly wrapped with copper wire and the other with magnesium wire. Observe the test tube for five to six days. Record the results of the observation in the science diary.

a) In which test tube, the iron nail undergoes rusting?
Answer:
The iron nail in contact with copper.

b) It is found that the iron nail in contact with copper corrodes easily while that in contact with magnesium is protected. Why does this happen?
Answer:
When a metal comes in contact with another metal in the presence of an electrolyte, it acts as a simple voltaic cell. This phenomenon is due to galvanic corrosion, an electrochemical process. When iron is in contact with copper, the more reactive iron acts as the anode and corrodes to protect the copper, the cathode. Conversely, when in contact with magnesium, the highly reactive magnesium acts as a sacrificial anode, corroding preferentially and preventing the less reactive iron from rusting.

c) When iron comes into contact with copper, which metal will release electrons? Why?
Answer:
When iron comes into contact with copper, iron will release electrons. This is because iron is more reactive than copper, meaning it has a greater tendency to lose electrons. As a result, in the presence of an electrolyte, iron becomes the anode and corrodes, while copper acts as the cathode and is protected from corrosion.

The iron atoms, that lose electrons, change into ions. The rate of corrosion of iron increases. Here iron acts as anode and copper acts as cathode.

d) Why is iron protected when it is in contact with magnesium?
Answer:
It is because the more reactive magnesium donates electrons. In the cell formed here, magnesium acts as anode and iron as cathode.

Question 30.
Which metal will corrode when two metals are in contact in the presence of moisture in the air?
The more reactive / The less reactive
Answer:
The more reactive
It is seen that the metal acting as anode is destroyed and the metal acting as cathode is protected. This is an important method to prevent corrosion of iron. This is known as cathodic protection.

Question 31.
Why is it not advisable to join aluminium wires and copper wires, and to join iron materials to copper piping
for electrical purposes?
Answer:
Joining aluminium and copper wires or iron and copper pipes is a bad idea due to galvanic corrosion and thermal expansion.

• Galvanic Corrosion: When in contact, the more reactive metal (aluminium or iron) corrodes faster to protect the less reactive one. This increases resistance and can cause fires.
• Thermal Expansion: Aluminium expands more than copper when heated. This difference can loosen the connection over time, increasing fire risk.

Question 32.
Why are zinc or magnesium blocks always attached to sea bridges and ship hulls?
Answer:
Zinc or magnesium blocks are attached to ships and bridges as sacrificial anodes. Being more reactive than steel, they corrode instead of the structure, providing cathodic protection.

Question 33.
Discuss various methods to prevent corrosion of metals and list them in the science diary.
Answer:
To prevent corrosion, you can:

• Coat the metal with paint or oil.
• Use a sacrificial coating, like galvanizing steel with zinc.
• Create alloys like stainless steel.
• Use cathodic protection with sacrificial anodes or electric current.
• Electroplate with a non-corrosive metal.

Metals play a crucial role in the human body also. We can learn more about it in the higher classes.

Std 10 Chemistry Chapter 6 Notes – Extended Activities

Question 1.
Thermite process

Mix equal amounts of anhydrous aluminium powder and iron oxide in a crucible. Immerse it in a tin pot filled with sand. Place a little of barium peroxide and magnesium powder mixture on top of the first mixture. Fix a 6 cm long polished magnesium ribbon in slanting position on its top. After lighting the ribbon, watch it from a distance.

After the reaction stops, examine the crucible and you will find a small globule of iron.
Fe₂O₃ + 2Al Al₂O₃ + 2Fe
a) Analyse the chemical changes that took place here based on the metallurgical process.
b) Find instances where thermite process is used in daily life.
c) Write the chemical equation for the production of chromium from chromic oxide (Cr₂O₃) in this way.
Answer:
a) The thermite process is a redox reaction. The aluminium powder acts as a strong reducing agent because it is more reactive than iron. It has a greater tendency to lose electrons and combine with oxygen. Aluminium reduces the iron oxide (Fe₂O₃) to molten iron (Fe), while the aluminium itself gets oxidised to aluminium oxide (Al₂O₃). The reaction is highly exothermic, releasing a large amount of heat that melts the iron. The barium peroxide and magnesium ribbon mixture acts as an igniter to initiate this high-temperature reaction.

b) The thermite process is utilised in daily life for its ability to produce extremely high temperatures and molten metal quickly. Common uses include:

Thermite Welding: It is widely used to weld railway tracks and other large metal parts in situ, as the process can generate molten iron to join the ends of the metal sections.

Demolition and Cutting: The intense heat from the reaction can be used to cut through thick metal plates.

c) The chemical equation for the production of chromium from chromic oxide (Cr₂O₃) using the thermite process is:
Cr₂O₃ + 2Al → Al₂O₃ + 2Cr
In this reaction, aluminium acts as the reducing agent, reducing the chromic oxide to pure chromium metal.

Question 2.
Prepare a note on how the rusted iron materials collected from the scrap iron shop are used in making steel. Present it in the class.
Answer:
Using Rusted Iron to Make Steel
Rusted iron from scrap yards is recycled into new steel through a process that primarily uses an electric arc furnace (EAF).

1. Melting: The scrap is placed in a high- temperature EAF, where the rust (iron oxide) and other impurities are melted.
2. Purification: Impurities like silicon and manganese are oxidised and then removed as slag.
3. Carbon and Alloying: Once purified, specific amounts of carbon and other elements (like chromium or nickel) are added to the molten iron to give it the desired properties of steel.
4. Casting: The new molten steel is then cast into various shapes for use in manufacturing.
   This process efficiently recycles metal, reducing the need for new iron ore mining and making steel production more sustainable.

Question 3.
Prepare a flow chart showing the various steps in the purification of bauxite.
Answer:

Metals Class 10 Notes

Metals Notes Pdf

• Minerals – The metallic compounds generally seen in the earth’s crust.
• Ores – A mineral from which a metal is economically, easily and quickly extracted.
• 3 Steps in metallurgy:
  1. Concentration of ores (removing impurities (gangue) from ore)
  2. Extraction of metals
  3. Refining of metals (Other metals, metal oxides, and small amounts of non-metals may be impurities in reduced metal. Metal refining removes impurities to make pure metal.)
• Concentration of ores
  1. Levigation (Gangue – Lighter, Ore – Heavier)
  2. Froth floatation (Gangue – Heavier, Ore – Lighter)
  3. Magnetic separation (Either ore or Gangue has magnetic nature)
  4. Leaching (when ore particles are soluble in suitable solution)
• Extraction of metals
  a) Conversion of the concentrated ore into its oxide.
  i) Calcination (Heating the ore at a temperature below its melting point in absence of air)
  ii) Roasting (Heating the ore at a temperature below its melting point in presence of air)
  b) Reduction of the oxide.
  Extraction of metal from the oxide.
• Refining of metals
  1. Liquation – Low melting metals
     Ex: Tin & Lead
     (Heating metals on an inclined surface)
  2. Distillation – Metals with low boiling points Zinc, Cadmium, Mercury
  3. Electrolytic Refining – Electrolysis (electrolyte – Solution of salt of metal, -ve electrode – small piece of pure metal, +ve electrode – impure metal)
• Industrial production of Iron
  Ore – Haematite –
  
  The chemical reactions taking place in blast furnace
  C + O₂ → CO₂ + Heat
  CO₂ + C + Heat → 2CO
  Fe₂O₃ + 3CO → 2Fe + 3CO₂
  CaCO₃ → CaO + CO₂
  CaO + SiO₂ → CaSiO₃
  Flux + Gangue → Slag
• Extraction of Zinc

The concentrated ore is subjected to roasting. Zinc sulphide converted to Zinc Oxide. Then Coke is mixed with Zinc oxide and put into furnace at high temperature, the coke reduces Zinc oxide to Zinc
Purification method of Zinc – Distillation

• Extraction of Copper – Copper is extracted from copper pyrites (CuFeS₂) through a process of concentration by froth flotation, followed by roasting and smelting with silica to remove iron as slag, which ultimately yields impure blister copper that is refined by electrolysis to obtain a high purity metal.
• Extraction of Aluminium – Aluminium is extracted from its ore, bauxite, in a two-stage process: first process purifies the bauxite to produce pure alumina (Al₂O₃), which is then dissolved in molten cryolite (Na₃ AlF₆) and reduced to pure aluminium metal by electrolysis in the Hall-Heroult process.
• Corrosion of metal is a process in which the metal reacts with a surrounding medium and undergoes chemical change.
• The factors given below influence the corrosion of metals move left.
• Nature of the metal
• Moisture in which gases or salts are dissolved Contact with other metals

INTRODUCTION

The use of metals accelerated the growth of people and the birth of an original culture. The discovery of metals and their role in human progress is amazing. The term ‘metal age’ refers to the transition period from the Stone Age to the use of metals. Our ancient period is marked by the names Copper Age, Bronze Age, Iron Age, etc. At present, metals are used in the making of a wide range of products, ranging from small paper screws to large-scale machinery. The unique features of each metal make them important in different fields.

Occurrence of metals in nature

• Naturally occurring metals or compounds are generally called minerals. These include metallic compounds and non metallic compounds.
• Any mineral from which a metal can be extracted easily and economically is called an ore of that metal.

Metallurgy

• The process of extraction of metal from ores involves three major stages. Such processes are generally referred to as metallurgy.
  1. Concentration of ores
  2. Extraction of metal from concentrated ore
  3. Refining of metal
• Concentration of ores is the process of increasing the metal content of the ore by removing impurities, known as gangue.
• Concentration methods include Levigation or Hydraulic washing, Froth floatation, Magnetic separation and Leaching. These methods are adopted depending on the nature of the ore and gangue.
• Extraction of metal from concentrated ore – 1. Conversion of concentrated ore to oxide, 2. Reduction of oxide ore
• Calcination refers to heating the concentrated ore in limited quantities or absence of air at a temperature below the melting point.
• Roasting refers to heating the concentrated ore at a temperature below the melting point in the presence of air.
• Refining of metals is the process of removing the impurities to produce pure metal. Refining methods include Liquation, Distillation and Electrolytic refining and these are adopted depending upon the metal to be purified and impurities contained in it.

Manufacturing methods of some industrially important metals

• Extraction of Iron – Iron is extracted from its iron oxide ores, such as haematite, in a blast furnace by reducing the iron oxide with carbon at high temperatures, which separates the iron from the oxygen.
• Extraction of Zinc – Zinc is extracted from its ores, primarily zinc sulphide (ZnS), by first converting the ore to zinc oxide (ZnO) through roasting, then reducing the oxide with carbon in a furnace at high temperatures, and finally purifying the resulting metal.
• Extraction of Copper – Copper is extracted from copper pyrites (CuFeS₂) through a process of concentration by froth flotation, followed by roasting and smelting with silica to remove iron as slag, which ultimately yields impure blister copper that is refined by electrolysis to obtain a high purity metal.
• Aluminium is extracted from its ore, bauxite, in a two-stage process: first process purifies the bauxite to produce pure alumina (Al₂O₃), which is then dissolved in molten cryolite (Na₃ AlF₆) and reduced to pure aluminium metal by electrolysis in the Hall-Heroult process.

Corrosion of metals

• Corrosion of metal is a process in which the metal reacts with a surrounding medium and undergoes chemical change.
• The factors given below influence the corrosion of metals.
  • Nature of the metal
  • Moisture in which gases or salts are dissolved
  • Contact with other metals

OCCURRENCE OF METALS IN NATURE
The earth’s crust is the major source of metals. Metals are generally found in combined state as they are highly reactive. Metal compounds like sodium chloride and magnesium chloride are dissolved in sea water also. A very few metals are seen in free state too. The most common examples include Gold (Au), Platinum (Pt), Silver (Ag).

The same metal can be found in the form of various minerals in nature. Metals are separated from the most suitable ones among these. For example, clay (Al₂O₃.2SiO₂.2H₂O) is an abundant mineral of aluminium. Bauxite
(Al₂O₃.2H₂O) and cryolite (Na₃AlF₆) are also minerals of aluminium. But among these, bauxite is the mineral that is commonly used to produce aluminium.

The qualities of a mineral that is used to extract a metal

• Abundance
• Ease of extraction
• High metal content
• Low production cost.

Based on these characteristics, bauxite is the most suitable mineral for the production of aluminium.
The ores of some metals are listed in the Table

METALLURGY
Highly reactive metals are found in nature in combined form.
The process of extraction of metal from ores involves three major stages. Such processes are generally referred to as metallurgy.
1. Concentration of ores
2. Extraction of metal from concentrated ore
3. Refining of metal

CONCENTRATION OF ORES
Ores are mined from the earth’s crust. A lot of earthy impurities like soil and sand may be mixed with this. Concentration of ores is the process of increasing the metal content of the ore by removing such impurities, known as gangue. Depending on the nature of the ore and gangue, various methods are adopted for this purpose.

a) Levigation or Hydraulic washing
This method is employed when the density of the ore is more than that of the gangue. The powdered ore is washed in a stream of water. The less dense gangue, which floats, is filtered out. The more dense ore remains at the bottom. Generally, oxide ores can be concentrated by this method.

b) Froth floatation
The froth floatation process is used when the ore is less dense than the gangue. The powdered ore is added to a mixture of water and pine oil and is stirred in a strong current of air. The ore particles stick to the froth formed, and float. It is removed and then the ore is separated and dried. Generally, sulphide ores are concentrated by this method.

c) Magnetic separation
When the powdered ore is passed through a magnetic roller, either the ore or the impurities having magnetic property is separated. In this way, pure ore is obtained by magnetic separation.

For example, magnetite (Fe₃O₄) ore has magnetic properties, but the gangue is non magnetic. Tinstone (SnO₂) ore is non magnetic, but iron tungstate, the gangue present in it is magnetic.

d) Leaching
The powdered ore is mixed with a suitable solvent. The ore dissolves in it or undergoes a chemical reaction to become a solution. The gangue remains insoluble in it. It is then filtered out. This process is called leaching.

Bauxite, the ore of aluminium, is concentrated in this way.

Metals such as gold and silver occur almost freely in nature. The ores of these metals are leached with a dilute solution of sodium cyanide (NaCN) or potassium cyanide (KCN) in the presence of air to extract the metals.

EXTRACTION OF METAL FROM CONCENTRATED ORE
You have learnt that the reactivity of metals differ. You also know about the reactivity series that is prepared based on this.

REFINING OF METALS
The metal extracted from concentrated ore may contain other elements or their compounds as impurities. Refining of metals is the process of removing these impurities to produce pure metal.

Various methods are adopted for this purpose depending upon the nature of the metal to be purified and the impurities contained in it. Some are given below.

(a) Liquation: When metals with low melting point contain impurities with high melting point, the metal is heated on the inclined surface of the furnace. The pure metal separates from the impurities, melts, flows down and it is collected. This is known as liquation. Metals such as tin (Sn) and lead (Pb) having low melting point can be purified by this method.

(b) Distillation: This method is used to purify metals with relatively low boiling points. When the metal containing impurities is heated under suitable conditions, only the pure metal vapourises. When this vapour condenses, pure metal is obtained. Metals like zinc (Zn), cadmium (Cd) and mercury (Hg) can be purified using this method.

(c) Electrolytic refining: In an electrolytic cell, an impure metal is used as the anode and a thin piece of pure metal is used as the cathode. A suitable salt solution of the same metal is used as the electrolyte. When electric current is passed, the pure metal alone is separated from the anode and deposited at the cathode.
Anode: M → Mⁿ⁺ + ne^–
Cathode : Mⁿ⁺ + ne^– → M
(Hint: M – metal, n – number of electrons involved in the reaction)
Copper (Cu) and zinc (Zn) can be purified in this way.

MANUFACTURING METHODS OF SOME INDUSTRIALLY IMPORTANT METALS
EXTRACTION OF IRON
Iron comprises about 5% of the earth’s crust and it is the second most abundant metal.

Steel
The pig iron obtained from the blast furnace is not suitable either for hammering into various shapes or for drawing into wires. The steel obtained from this is used for various industrial purposes. Steel is iron containing 0.05% to 1.5% carbon. There are different types of carbon steels depending on the amount of carbon. They differ in properties also.

EXTRACTION OF ZINC
Zinc is another industrially important metal.

EXTRACTION OF COPPER
Principal ores of copper
Copper pyrites – CuFeS₂ Copper glance – Cu₂S

EXTRACTION OF ALUMINIUM
Aluminium is produced by Hall-Heroult process.
It has two stages.

1. Concentration of bauxite
Bauxite is concentrated by leaching. The powdered ore is treated with hot concentrated
sodium hydroxide (NaOH) solution. The ore alone dissolves in it to form sodium aluminate
(NaAlO₂) solution. Impurities are then filtered off.
Al₂O₃.2H₂O + 2NaOH → 2NaAlO₂ + 3H₂O

A little aluminium hydroxide (Al(OH))₃ is added to the solution of sodium aluminate and stirred vigorously. It is diluted by adding water. As a result, pure aluminium hydroxide separates out from the solution.
NaAlO₂ + 2H₂O → Al(OH)₃ + NaOH
If the aluminium hydroxide thus obtained is heated strongly, anhydrous alumina (Al₂2O₃) is obtained.
2Al(OH)₃ Al₂O₃ + 3H₂O

2. Electrolysis of aluminium oxide
Molten cryolite (Na₃AIF₆) is added to the alumina, obtained after concentration, to get a solution. This is the electrolyte used in the production of aluminium. The melting point of alumina is 2017°C. Cryolite is added to reduce the melting point and to increase the electrical conductivity.

Aluminium is separated at the cathode when a high voltage electric current is passed through the molten mixture. Examine the chemical equations of the reactions.
Al₂O₃ → 2Al³⁺ + 3O^2-

CORROSION OF METALS
Corrosion of metal is a process in which the metal reacts with a surrounding medium and undergoes chemical change.

Students rely on Class 10 Chemistry Notes Kerala Syllabus Chapter 5 Important Questions with Answers Electrochemistry to help self-study at home.

SSLC Chemistry Chapter 5 Important Questions Kerala Syllabus

Electrochemistry Class 10 Important Questions

Question 1.
Which substance is deposited at the cathode when aqueous Sodium Chloride is electrolysed? [Oxygen, Chlorine, Sodium, Hydrogen]
Answer:
Hydrogen

Question 2.
In the process of electroplating copper on an iron bangle, the bangle is connected to which terminal of the battery?
Answer:
Negative terminal

Question 3.
Statement 1: A Galvanic cell is an electrochemical cell that converts chemical energy into electrical energy.
Statement 2: A galvanic cell requires an external power source to function.
Which of the following is correct regarding the above statements?
A. Both statements are correct
B. Both statements are not correct
C. Only statement 1 is correct
D. Only statement 2 is correct
Answer:
C. Only statement 1 is correct
Galvanic cells generate electrical energy spontaneously and do not require an external power source

Question 4.
a) Which of the following metals reacts vigorously with diluted hydrochloric acid?
a) Gold
b) Magnesium
c) Lead
d) Iron
Answer:
b) Magnesium

Question 5.
Match the following.

Choose the correct answer from the options given below.
a) 1 – b, 2 – a, 3 – c
b) 1 – c, 2 – a, 3 – b
c) 1 – a, 2 – c, 3 – b
d) 1 – c, 2 – a, 3 – b
Answer:
a) 1 – b, 2 – a, 3 – c

Question 6.
Find out whether the following statements are true or false. If false, correct the statement.
I. Oxidation takes place at the cathode in the galvanic cell.
II. Electrical energy is converted into chemical energy in an electrolytic cell.
III. Electrical energy is converted into chemical energy in a galvanic cell.
Answer:
I) False – Oxidation takes place at the anode in a galvanic cell.
II) True
III) False – Chemical energy is converted into electrical energy.

Question 7.
a) In which test tube displacement reaction take place

b) Why doesn’t the displacement reaction take place in one of the test tubes?
Answer:
a) Test tube 1
b) In the second test tube, Ag is less reactive than copper. So, a displacement reaction cannot occur.

Question 8.
Copper is electroplated on an iron ring.
a) Which electrolyte is used here?
b) Which metal is connected to the positive terminal of the battery?
Answer:
a) Copper sulphate solution
b) Cu

Question 9.
Name the electrolytes used for the electrolysis of copper, silver and gold.
Answer:

Question 10.
A student draws the arrangement of a galvanic cell as shown below. Find out if there is any mistake? If so, draw the correct picture of the galvanic cell.

Answer:

Each metal should be placed in its own salt solution; that is, the Zn rod should be dipped in ZnSO₄, and the Cu rod should be dipped in CuSO₄.If the arrangement is correct, electron flow is from Zinc to copper.

Question 11.
a) Which is the anode and cathode in the Mg – Ag galvanic cell?
b) Write the reaction taking place at anode and cathode of this cell.
c) Write the equation of a redox reaction.
Answer:
a) Anode – Mg, Cathode – Ag

b) Anodic reaction: Mg → Mg²⁺ + 2e^–
Cathodic reaction: 2Ag⁺ + 2e^– → 2Ag

c) Redox reaction: Mg + 2Ag⁺ → Mg²⁺ + 2Ag

Question 12.
Observe the figure in which a copper plate is immersed in AgNO₃ (Silver Nitrate) solution. (Reactivity: Cu > Ag)

a) The reaction taking place here is a redox reaction. Why?
b) What change can be observed on the copper plate?
c) Write the equation of the oxidation reaction taking place here.
Answer:
a) Oxidation and reduction take place simultaneous!}’, so this reaction is a redox reaction.
b) A layer of Ag is deposited on the Copper plate, and the silver nitrate solution turns blue.
c) Cu → Cu²⁺ + 2e^–

Question 13.
A galvanic cell is constructed using Mg and Cu as electrodes.
a) What is the energy change taking place in a galvanic cell?
b) Which is the anode of the given galvanic cell?
c) Write the equation of the chemical reaction taking place at the cathode.
Answer:
a) Chemical energy is converted into electrical energy.
b) Mg
c) Cu²⁺ + 2e^– → Cu

Question 14.
The figure given below represents metals like Fe, Cu, and Mg kept in dilute HCl

a) Which among these test tubes didn’t show any reaction? Which metal was kept in that test tube?
b) Which metal is present in test tube 1? Give an equation for this reaction.
c) Arrange the given metals in the increasing order of their reactivity towards acids.
Answer:
a) 3^rd test tube, Cu

b) Mg. Because Mg reacts vigorously with HCl, more H₂ gas is produced.
Mg + 2HCl → MgCl₂ + H₂
c) Mg > Fe > Cu

Question 15.
Analyse the picture of an experiment.
a) What change took place on the surface of the iron nail?

b) Which among the following reactions are involved in the above change?
Fe²⁺ + 2 e^– → Fe
Ag⁺ + 1 e^– → Ag
Fe → Fe²⁺ + 2e^–
Ag → Ag⁺ + 1 e^–

c) Which is oxidised? Which is reduced?
Answer:
a) Ag is deposited on the nail.
b) Fe → Fe²⁺ + 2e^–
Ag⁺ + 1 e^– → Ag
c) Fe is oxidised, Ag⁺ is reduced.

Question 16.
Some materials are given below:

a) From the given materials, choose the appropriate ones to constmct a galvanic cell and draw the diagram of the cell. (Order of reactivity: Mg > Fe > Cu > Ag)
b) Which is the anode of this cell?
c) At which electrode does reduction take place?
d) Write the chemical equation of the reaction taking place at the cathode.
Answer:
a) Mg, MgSO₄, Cu, CuSO₄, Salt bridge, connecting wire with voltmeter connected.

b) Mg/Magnesium
c) Cathode (Cu rod)
d) Cu²⁺ + 2e^– → Cu

Question 17.
The zinc rod is dipped in CuSO₄ solution. Observe the changes taking place after some time.
a) Which metal is more reactive, Zn or Cu?
b) Which metal is displaced during this reaction?
c) Is this a redox reaction? Give reason.
Answer:
a) Zn

b) Cu

c) Yes. Here, Zn gets oxidised, and Cu is reduced. Thus, both oxidation and reduction take place simultaneously. So, this is a redox reaction.

Question 18.
Analyse the picture of an experiment.

a) What is the reason for the decrease in the green colour of the FeSO₄ solution?
b) The equation for this reaction is given below. Complete it.
Zn + FeSO₄ → ……… + ZnSO₄
c) If Pb is used instead of Zn, no reaction takes place. From this, what inference regarding the reactivity of lead can be obtained?
Answer:
a) Zn displaces iron from the FeSO₄ solution.
b) Zn + FeSO₄ → Fe + ZnSO₄
c) Pb is less reactive than Zn.

Question 19.
Observe the pictures given below. Based on the reactivity series, predict which of these undergoes a displacement reaction. Complete the table.

Answer:
a) Takes place
b) Does not take place
c) Takes place
d) Does not take place

Question 20.
a) Draw a diagram of the setup for electroplating gold onto a copper bangle and label its parts.
b) What are the advantages of electroplating?
c) A picture of the arrangement of copper plating on an iron bangle is given below. What are the mistakes in this?

Answer:
a)

b)

• It enhances the beauty of metal
• Prevents corrosion

c) Copper should be connected to the positive terminal of the battery.
The iron bangle should be connected to the negative terminal of the battery.
Copper sulfate solution should be used as the electrolyte.

Students rely on SCERT Kerala Syllabus 10th Standard Chemistry Textbook Solutions and Class 10 Chemistry Chapter 5 Electrochemistry Notes Questions and Answers English Medium to help self-study at home.

SSLC Chemistry Chapter 5 Notes Questions and Answers Pdf Electrochemistry

SCERT Class 10 Chemistry Chapter 5 Electrochemistry Notes Pdf

SSLC Chemistry Chapter 5 Questions and Answers – Let Us Assess

Question 1.
Examine the diagram of a galvanic cell and find out whether the given statements are true or false.

a) As the cell operates, the mass of the zinc rod, Zn(s) decreases.
b) The copper electrode is the anode.
c) Electrons flow from the zinc electrode to the copper electrode through the external circuit.
d) During cell reaction, reduction takes place at the copper electrode.
e) During cell reaction, the concentration of Cu2+ decreases.
Answer:
a) True
b) False: Copper is the cathode (site of reduction). Zinc is the anode.
c) True
d) True
e) True

Question 2.
The chemical equation of the reaction taking place in a galvanic cell is given.
Zn(s) + 2Ag⁺(aq) → Zn²⁺(aq) + 2Ag(s)
a) Represent diagrammatically the above galvanic cell.
b) Which electrode has a negative charge?
c) What is the reaction taking place at each electrode?
Answer:
a)
b) The zinc electrode is negatively charged.
c) Anode: Zn(s) → Zn²⁺ + 2e^– [Oxidation]
Cathode: 2Ag⁺ + 2e^– → 2Ag(s) [Reduction]

Question 3.
A galvanic cell is made up of the following half cells:
• A magnesium electrode immersed in magnesium sulphate solution.
• A nickel electrode immersed in nickel sulphate solution.
The reactions taking place in the half-cells are given.
Mg (s) → Mg²⁺ (aq) + 2e^–
Ni²⁺(aq) + 2e^– → Ni(s)
Draw the cell diagram and label the anode, cathode and direction of flow of electrons.
Answer:

Question 4.
When an aqueous sodium chloride solution is electrolysed, the reaction that takes place at the anode is:
(i) Na⁺(aq) + e^– → Na(s)
(ii) 2H₂O → 4H⁺(aq) + O₂(g) + 4e^–
(iii) H⁺ (aq) + e^– → 1/2H₂(g)
(iv) Cl^– (aq) → 1/2 Cl₂ +e^–
Answer:
The reaction at the anode is:
Cl^– (aq) → Cl₂(g) + e^–

Question 5.
Write the products obtained when the following solutions undergo electrolysis.
(i) Aqueous solution of NaCl
(ii) Aqueous solution of CuSO₄ (using copper electrodes)
Answer:
(i) At Cathode (-): Water is reduced → Hydrogen gas (H₂) is released.
2H₂O + 2e^– → H₂ + 2OH^–
At Anode (+): Chloride ions are oxidised → Chlorine gas (Cl₂) is released.
2Cl → Cl₂ + 2e^–
Products: Hydrogen gas, Chlorine gas, and Sodium hydroxide (NaOH in solution).

(ii) At Cathode (-): Copper ions are reduced → Copper metal is deposited.
Cu²⁺ + 2e^– → Cu
At Anode (+): Copper electrode dissolves (oxidation).
Cu → Cu²⁺ + 2e^–
Products: Copper is deposited on the cathode and at anode copper dissolves as ions.

Question 6.
Brass is an alloy of zinc and copper. When brass comes into contact with saline water, corrosion of metal takes place and zinc gradually dissolves in the solution, leaving copper behind. Explain why zinc dissolves in comparison to copper.
Answer:
Zinc is more reactive than copper as it lies above copper in the reactivity series. When brass is exposed to saline water (which contains electrolytes), zinc atoms lose electrons more readily and go into solution as Zn²⁺ ions. Copper, being less reactive, does not dissolve as easily and remains behind.

Question 7.
List the cells we use in our daily life and classify them into primary and secondary cells.
Answer:
Primary cells (non-rechargeable): Dry cell (used in torches, clocks, toys), Mercury cell, Lithium cell (in calculators, watches).

Secondary cells (rechargeable): Lead-acid battery (car battery), Nickel-Cadmium cell, Lithium-ion battery (in mobiles, laptops).

Question 8.
Define fuel cells and write their advantages.
Answer:
A fuel cell is a device that converts the chemical energy produced by the combustion of fuel directly into electrical energy.

Advantages:

1. High efficiency.
2. Environment-friendly (produces water as a by-product in hydrogen fuel cells).
3. Continuous supply of electricity as long as fuel is provided.

Chemistry Class 10 Chapter 5 Notes Kerala Syllabus Electrochemistry

Question 1.
a) What did you observe?
Answer:
The bulb glows.

b) What is the reason for the glowing of the bulb?
Answer:
The bulb glows because chemical energy is converted into electrical energy in the electrochemical cell.
We can understand that there is a flow of electric current through the bulb.

Separate the copper wires from the bulb and connect them to a galvanometer as shown in the figure given below. When the copper rod is connected to the positive terminal of the galvanometer and the zinc rod to the negative terminal, it can be seen that the pointer of the galvanometer is deflecting towards the right (towards the positive terminal)

This proves that:
• Electrons flow from the zinc rod to → copper rod.
• Electric current flows in the opposite direction (copper → zinc) through the galvanometer.
Connect a voltmeter instead of the galvanometer as shown in the figure below.

SALT BRIDGE

• A salt bridge is a U-shaped glass tube filled with an inert electrolyte.
• Common electrolytes used:
  • Potassium chloride (KCl)
  • Ammonium chloride (NH₄Cl)
  • Potassium nitrate (KNO₃)
• The electrolyte is made into a gel using agar-agar.
• It connects the oxidation and reduction half-cells in a galvanic cell.
• It allows electrical contact between the two solutions without mixing them.
• Maintains electrical neutrality by allowing ion flow.
• Enables smooth operation of the galvanic cell.

Examine the metal rods and the solutions in which they are immersed in the figure below.

Question 2.
Find the voltage between the two electrodes?
Answer:
The voltmeter shows a reading of about 1.1 volts. This means the voltage (potential difference) between zinc and copper electrodes is approximately 1.1 V.
The reaction that occurs at each electrode is given below.
Zinc electrode: Zn(s) → Zn²⁺ (aq) + 2e^–

Question 3.
What type of chemical reaction takes place at the zinc electrode? (Oxidation / Reduction)
Answer:
Oxidation
Copper electrode: Cu²⁺(aq) + 2e^– → Cu(s)

Question 4.
What type of chemical reaction takes place at the copper electrode?
Answer:
Reduction
Anode: The electrode where oxidation occurs is called the anode
Cathode: The electrode where reduction occurs is called the cathode.
The processes that take place in the Daniel cell can be summarised as:
Anode: Zn(s) → Zn²⁺ (aq) + 2e^–
Copper electrode: Cu²⁺(aq) + 2e^– → Cu(s)
Cell reaction: Zn(s) + Cu²⁺ (aq) → Zn²⁺(aq) + Cu(s)
The electric current is produced as a result of a redox reaction taking place in the galvanic cell.

In the Daniel cell, replace the zinc rod in zinc sulphate with aluminium, silver and magnesium rods (plates) and immerse these metals in their own salt solution. Repeat the experiment by connecting each to the copper rod immersed in copper sulphate.

Question 5.
a) List out the direction of flow of electrons, the equation of reaction at each electrode, the cell voltage, and analyse them.

Answer:

b) Which has the higher value of voltage, Zn – Cu galvanic cell or Al – Cu galvanic cell?
Answer:
Al – Cu galvanic cell has the higher voltage.
The tendency of aluminium to get oxidised in redox reactions is greater than that of zinc. That is, aluminium is more reactive than zinc.
Zn – Cu cell voltage = 0.34 – (-0.76) = 1.10 V
Al – Cu cell voltage = 0.34 – (-1.66) = 2.00 V

c) Which has the higher value of voltage, Mg – Cu galvanic cell or Al-Cu galvanic cell?
Answer:
The voltage value for the Mg-Cu galvanic cell is higher.

d) What is the direction of flow of electrons in a galvanic cell made up of a pair of copper and silver electrodes?
Answer:
Cu acts as anode and Ag acts as cathode. So, Electrons flow from copper to silver.

Question 6.
Draw a diagram of the galvanic cell having silver and copper as electrodes and mark the direction of flow of electrons.
Answer:

CELL VOLTAGE
The cell voltage is the potential difference between the two electrodes of a cell when no current is flowing.

Question 7.
Prepare a list of the metals, familiarised through the experiment, in the order of their tendency to get oxidised in redox reactions.

Answer:

In this way, we can construct galvanic cells using different elements as electrodes and compare their reactivities.

REACTIVITY SERIES.
The series in which elements are arranged in decreasing order of their reactivity is known as the reactivity series.

APPLICATION OF THE REACTIVITY SERIES

1. To identify which metal is being displaced
Place a zinc rod in a beaker of copper sulphate solution. Observe for some time.
a) Did the colour of the CuS04 solution change?
Answer:
Yes, the blue colour of the CuS04 solution faded and eventually disappeared.

b) What change was observed in the zinc rod?
Answer:
The zinc rod became coated with a reddish- brown deposit.

c) What may be the reason for the fading of the colour of the solution?
Answer:
A decrease in the concentration of Cu2+ ions is the reason for the fading of the blue colour.

d) With the help of the reactivity series, find out which metal is more reactive, Zn or Cu?
Answer:
Zinc (Zn) is more reactive than copper (Cu).

e) What are the ions fonned when CuSO₄ dissolves in water?
Answer:
Cu²⁺ (copper ions) and SO₄^2- (sulphate ions).

f) What changes have occurred to the Cu²⁺ ions?
Answer:
The Cu²⁺ ions have gained two electrons and have been converted to solid copper atoms (Cu). This process is called reduction.

g) Write the chemical equation of the reaction.
Answer:
Zn + Cu²⁺SO₄^2- → Zn²⁺SO₄^2- + Cu

h) What changes have occurred to Zn?
Answer:
The zinc (Zn) atoms have lost two electrons and have been converted into zinc ions (Zn²⁺). This process is called oxidation.

i) Which metal is displaced here?
Answer:
In the reaction between zinc (Zn) and copper sulfate (CuSO₄), copper (Cu) is the metal being displaced. This is a single displacement reaction, where the more reactive metal, zinc, displaces the less reactive metal, copper, from its compound.

Take a little silver nitrate solution in a beaker and dip a copper rod in it. Observe for some time.
a) Is there any change in the colour of the solution?
Answer:
Yes, the solution gradually turns blue because of the formation of Cu²⁺ ions.

b) What change was observed in the copper rod?
Answer:
A greyish-white layer of silver metal gets deposited on the copper rod.

c) Write the equation of the chemical reaction taking place here.
Answer:
Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag

d) Explain the reaction by comparing the positions of Ag and Cu in the reactivity series.
Answer:
In the reactivity series, copper (Cu) is above silver (Ag), which means copper is more reactive than silver.

e) Complete this chemical equation by assigning oxidation numbers.
Answer:

f) Which ion is responsible for the change in the colour of the solution?
Answer:
The Cu²⁺ ion is responsible (makes the solution blue).

g) Which metal is oxidised here?
Answer:
Copper (Cu) is oxidised.

h) Complete the equation for oxidation.
Answer:
Cu → Cu²⁺ + 2e^–

i) Which one is reduced here?
Answer:
Silver ion (Ag⁺) is reduced to metallic silver (Ag).

j) Write the equation for reduction.
Answer:
Ag⁺ + e^– → Ag

Question 8.
Silver nitrate solution cannot be stored in a copper vessel. Why?
Answer:
Copper (Cu) is more reactive than silver (Ag) in the reactivity series. So, copper will displace silver from the silver nitrate solution:
Cu + 2AgNO₃ → Cu (NO₃)₂ + 2Ag
As a result, the copper vessel will gradually dissolve (forming blue copper nitrate solution), and silver will get deposited. This reaction would spoil both the vessel and the solution.

2. To identify the oxidising agent and the reducing agent
Question 9.
Consider the displacement reaction given below.

a) Which metal is oxidised here?
Answer:
Magnesium (Mg)

b) Write the equation for oxidation.
Answer:
Mg → Mg²⁺ + 2e^–

c) Which metal is reduced here?
Answer:
Copper (Cu)

d) Write the equation for reduction.
Answer:
Cu²⁺ + 2e^– → Cu

e) Which reaction occurs to the more reactive metal? (Oxidation/Reduction)
Answer:
Oxidation

f) Which reaction occurs to the less reactive metal?(Oxidation/Reduction)
Answer:
Reduction

g) What is the oxidising agent and the reducing agent in this reaction?
Answer:
Cu²⁺ is the oxidising agent and Mg is the reducing agent.

h) What happens to the oxidising agent in this redox reaction?
Answer:
The oxidising agent gets reduced

i) What happens to the reducing agent?
Answer:
The reducing agent gets oxidised.

Question 10.
Identity the oxidising agent and reducing agent in the reaction Given below.
2AgNO₃ + Cu → Cu(NO₃)₂ + 2Ag
Answer:
Oxidising agent: AgNO₃ (because Ag+ is reduced) Reducing agent: Cu (because it is oxidised)

3. To identify the displacement of hydrogen from the acid
Take equal amounts of dilute HCl in different test tubes as shown in Figure. Treat equal masses of polished Fe, Mg, Cu, Pb, Zn with dilute hydrochloric acid.

a) In which of the test tubes is hydrogen gas produced?
Answer:
Hydrogen gas is produced in the test tubes containing:

• Fe (Iron)
• Mg (Magnesium)
• Pb (Lead)
• Zn(Zinc)

Not produced in the Cu (Copper) test tube, because copper is below hydrogen in the reactivity series and cannot displace hydrogen from dilute HCl.

b) Is the rate of formation of hydrogen gas the same in all the test tubes?
Answer:
No, the rate of formation of hydrogen gas is not the same in all test tubes.
It depends on the reactivity of the metal with dilute HCl.
Mg > Zn > Fe > Pb > Cu (no reaction)

c) Examine the position of hydrogen and the metals used here in the reactivity series and record your observations.
Answer:
Metals above hydrogen in the reactivity series
(Mg, Zn, Fe, Pb) can displace hydrogen from dilute acids and produce hydrogen gas.
Copper (Cu) is below hydrogen in the reactivity series, so it cannot displace hydrogen from dilute HCl. Hence, no reaction is observed.

Question 11.
Which of the following metals can displace hydrogen from hydrochloric acid?
[Sodium, gold, silver, aluminium]
Answer:
Sodium (Na) and Aluminium (Al) can displace hydrogen from hydrochloric acid because they are above hydrogen in the reactivity series.

Gold (Au) and Silver (Ag) are below hydrogen in the reactivity series, so they cannot displace hydrogen from hydrochloric acid.

Question 12.
a) Bring a burning candle close to the mouth of the test tubes and record the observations.
Answer:
When you bring a burning candle to the test tube near the cathode, a “pop” sound will be heard, and the gas will ignite. This indicates the presence of hydrogen gas.

When you bring the burning candle to the test tube near the anode, the flame will bum more brightly. This indicates the presence of oxygen, as it supports combustion.

b) Which gas is produced in each test tube?
Answer:
At the cathode (negative electrode): Hydrogen gas (H₂) is produced. This is the test tube with the larger volume of gas.

At the anode (positive electrode): Oxygen gas (O₂) is produced. This is the test tube with the smaller volume of gas.

c) Write the chemical equation of the reaction.
Answer:
The overall chemical equation for the electrolysis of water is:

Here, acidified water decomposes into hydrogen and oxygen. This is because of the flow of electricity from the external electrical source into the solution through the electrodes.

Observe the given figure

Carry out this electrolysis with the help of the teacher.
Question 13.
Record your observations.
a) Which metal is connected to the positive terminal of the battery?
Answer:
Copper

b) Which metal is connected to the negative terminal of the battery?
Answer:
Iron

c) Which solution is used as the electrolyte?
Answer:
Copper sulphate solution

d) What are the ions present in the electrolyte?
Answer:
The ions present are copper cations (Cu²⁺) and sulphate anions (SO₄^2-).

e) Which electrode is connected to the positive terminal of the battery? Anode/Cathode
Answer:
Anode

f) What is the reaction taking place at the anode?
Answer:
Oxidation

g) Complete the equation of the oxidation reaction taking place at the copper plate.
Answer:
Cu → Cu²⁺ + 2e^–

h) Which electrode is connected to the negative terminal of the battery?
Anode/Cathode
Answer:
Cathode

i) What is the reaction taking place at the cathode?
Answer:
The reaction taking place at the cathode is reduction.

j) Which ions will be attracted to the cathode, the iron ring, from the solution?
Answer:
Copper ions (Cu²⁺) will be attracted to the cathode (the iron ring) from the solution.

k) Complete the equation of the reduction reaction taking place here.
Answer:
Cu²⁺ + 2e^– → Cu

The reactions taking place at the anode and cathode:
Anode: Cu → Cu²⁺ + 2e^–
Cathode: Cu²⁺ + 2e^– → Cu
That is, at the anode, copper undergoes oxidation and enters into the solution as Cu²⁺ ions. At the same time, Cu²⁺ ions from the solution are reduced on the surface of the iron ring, which is the cathode, forming a thin coating of copper on it.

Question 14.
What are the benefits of electroplating?
Answer:
It enhances the beauty of the metal and prevents its corrosion.

Question 15.
Explain the process of electroplating.
Answer:

• The metal that is to be plated should be connected to the positive terminal of the battery.
• The object on which the plating is to be done should be connected to the negative terminal of the battery.
• A salt solution of the metal to be plated is used as the electrolyte

Std 10 Chemistry Chapter 5 Notes – Extended Activities

Question 1.
The following are certain observations about metals A, B, C and D.
(a) When a plate of metal A is placed in a solution containing B²⁺ ions, no reaction is observed.
(b) When the plate of A is placed in a solution containing C⁺ ions, no change occurs.
(c) When a plate of metal D is placed in a solution containing C⁺ ions, a black precipitate of C is formed on the surface of D, and the presence of D²⁺ ions can be detected in the solution.
(d) When a plate of B is placed in a solution of D²⁺ ions, D appears on the surface of B and B²⁺ ions appear in the solution.
List A⁺, B²⁺, C⁺ and D²⁺ in the ascending order of their ability to attract electrons.
Answer:
The tendency to lose an electron varies in the following order.
C < D < B
Therefore, the ascending order of their ability to attract electrons is.
B²⁺ < D²⁺ < C⁺ < A⁺

Question 2.
As shown in the galvanic cell of the given figure, place a silver electrode in a solution of silver nitrate and a lead electrode in a solution of lead nitrate. Connect the two electrodes using a copper wire. Also connect the two breakers using a salt bridge. Next, find the answers to the questions given below.

(a) What is the anode
(b) What is the cathode?
(c) Where does oxidation occur?
(d) Where does reduction occur?
(e) In which direction do electrons flow through the copper wire?
(f) What will be the cell voltage?
(g) Will the cell voltage vary if the two solutions are diluted alternately?
Answer:
a) Anode is where oxidation occurs.
Lead (Pb) electrode

b) Cathode is where reductions occur.
Silver (Ag) electrode

c) At the lead (Pb) electrode

d) At the silver (Ag) electrode

e) From the lead electrode to the silver electrode

f) Standard electrode potentials:

• Pb²⁺/Pb = -0.13 V
• Ag⁺ /Ag = +0.80 V
  Cell Voltage =Potential of Cathode – Potential of Anode = 0.80 V – (-0.13 V) = 0.93 V

g) Yes, the cell voltage will vary if the solutions are diluted. The cell voltage depends on the concentration of the ions. Diluting the solutions changes the ion concentrations, which affects the electrode potential and thus alters the overall cell voltage.

Electrochemistry Class 10 Notes

Electrochemistry Notes Pdf

• Electrochemistry: Study of electricity-related chemical reactions.
• Electrochemical cells: Devices that convert chemical energy to electrical energy or vice versa.
• Types of Electrochemical Cells
  • Galvanic cells: Convert chemical energy to electrical energy.
  • Electrolytic cells: Convert electrical energy to chemical energy.
• Galvanic Cell (Daniell Cell)
  • Oxidation takes place at the anode (Negative electrode).
  • Reduction takes place at the cathode (Positive electrode).
• Electrolytic cell
  • Oxidation takes place at the anode (Positive electrode).
  • Reduction takes place at the cathode (Negative electrode).
• Reactivity Series: Arrangement of elements in decreasing order of reactivity is called the reactivity series.
• Displacement Reactions: More reactive metals displace less reactive metals from salt solutions.
  Zn + CuSO₄ → ZnSO₄ + Cu
• Oxidising & Reducing Agents
  • Oxidising agent: Gains electrons (gets reduced).
  • Reducing agent: Loses electrons (gets oxidised).
• Hydrogen Displacement
  • Metals above hydrogen in the reactivity series displace H₂ from acids.
  • Reactive metals (Mg, Zn, Fe, Pb) react with HCl to release H₂ gas.
  • Unreactive metals (Cu, Ag, Au) do not.
• Electrolysis of molten sodium chloride
  • Ions: Na⁺, Cl^–
  • At Cathode: Na⁺ + e^– → Na (molten)
  • At Anode: 2Cl^– → Cl₂ + 2e^–
  • Products: Na (metal), Cl₂ (gas)
• Electrolysis of aqueous sodium chloride
  • At Cathode: 2H₂O + 2e^– → H₂ + 2OH^–
  • At Anode: 2Cl^– → Cl₂ + 2e^–
  • Products: H₂ gas, Cl₂ gas, NaOH solution
• Electroplating
  • Anode (positive): Metal to be plated (e.g., Cu)
  • Cathode (negative): Object to be plated (e.g., Iron ring)
  • Electrolyte: Salt solution of plating metal (e.g., CuSO₄)
• Benefits
  • Enhances appearance
  • Prevents corrosion
• Applications of electrolysis:
  • Production of metals: Na, K, Ca, Al
  • Production of non-metals: H₂, O₂, Cl₂
  • Manufacture of compounds: NaOH, KOH
  • Electroplating: Jewellery, utensils
  • Purification of metals: Cu, Au
• Different types of cells
  • Primary Cells: Non-rechargeable [Examples: Dry cell, Button cell]
  • Secondary Cells: Rechargeable [Examples: Lead-acid battery, Li-ion battery, Ni-Cd cell]
    Fuel Cells: Fuel cells are galvanic cells that use fuels like H,, CH₄, or CH₃OH to continuously and efficiently convert chemical energy directly into electrical energy in an environmentally friendly manner

INDRODUCTION

In our daily lives, we use many devices, such as vehicles, mobile phones, laptops, and medical equipment. All these works with the help of stored electrical energy from cells or batteries. Chemical reactions inside them produce this energy. Electrochemistry is the branch of chemistry that studies how chemical reactions can produce electricity and how electricity can be used to carry out chemical reactions. The devices that make this possible are called electrochemical cells.

In this unit, we will learn about electrochemical cells, the reactivity series and its applications, electrolytic cells, electrolysis of molten sodium chloride, electrolysis of aqueous sodium chloride solution, electroplating and its uses, and different types of cells

Electrochemical Cells

• Devices that convert chemical energy into electrical energy (or vice versa).
• Made of two electrodes (anode and cathode) and an electrolyte.
• Work on redox reactions where oxidation occurs at the anode and reduction at the cathode.
• Examples: Galvanic (Voltaic) cells and Electrolytic cells.

Electrolysis of Molten Sodium Chloride

• Process of breaking down molten NaCl using electricity.
• At the cathode: Na⁺ ions are reduced to sodium metal.
• At the anode: Cl^– ions are oxidised to chlorine gas.
• Overall: Production of sodium metal and chlorine gas.

Electrolysis of Aqueous Sodium Chloride Solution

• Involves electrolysis of aqueous sodium chloride solution.
• At the cathode: Water is reduced to hydrogen gas.
• At the anode: Cl^– is oxidised to chlorine gas.
• Solution left behind is sodium hydroxide (NaOH).

Electroplating

• Coating one metal with another using electrolysis.
• Cathode: Object to be plated.
• Anode: Metal to be deposited.
• Electrolyte: Salt solution of the coating metal.
• Used for decoration, corrosion protection, and improving durability.

Applications of Electrolysis

• Extraction of metals (e.g., aluminium from alumina, sodium from NaCl).
• Purification of metals (e.g., copper).
• Electroplating (jewellery, utensils, machine parts).
• Production of metals and non-metals.

Different Types of Cells

• Primary Cells: Non-rechargeable [Examples: Dry cell, Button cell]
• Secondary Cells: Rechargeable [Examples: Lead-acid battery, Li-ion battery, Ni-Cd cell]
• Fuel Cells: Generate electricity from a continuous supply of fuel and oxygen (e.g., hydrogen fuel cell).

ELECTROCHEMICAL CELLS
Electrochemistry is the branch of chemistry that deals with the study of the processes that produce electricity through chemical reactions and use electricity to bring about chemical reactions. Electrochemical cells are the devices that make such changes possible. Electrochemical cells can be divided into two types.

1. Galvanic cells
2. Electrolytic cells

GALVANIC CELL
Galvanic cells are devices that convert chemical energy into electrical energy. Daniel cell is an example of a galvanic cell.

METHOD OF CONSTRUCTING A DANIEL CELL
Materials Required:

• Beaker
• Zinc rod
• Copper rod
• Zinc sulphate solution
• Copper sulphate solution
• Salt bridge
• NH₄Cl/KCl/KNO₃
• Copper wires
• Galvanometer
• Voltmeter
• LED bulb

Experimental procedure

• Take two beakers.
  • In one beaker, pour zinc sulphate solution and dip a zinc rod (Half cell 1).
  • In the other beaker, pour copper sulphate solution and dip a copper rod (Half cell 2).
• Make a salt bridge:
  • Roll a piece of filter paper.
  • Add some KCl (Potassium chloride) / NH₄Cl (Ammonium chloride) / KNO₃ (Potassium nitrate) crystals.
  • Sprinkle water to moisten it.
  • Bend it into a ‘U’ shape.
• Place the salt bridge so that it connects the two beakers.
• Connect the zinc rod and copper rod to a bulb using copper wires.

ELECTROLYTIC CELLS
The cells that utilise electrical energy to bring about chemical changes are called electrolytic cells.

EXPERIMENT: ELECTROLYSIS OF produced?
ACIDIFIED WATER
Procedure of the experiment:
Take a plastic cup. Make two holes at the bottom and attach rubber stoppers as shown in the Figure. Insert carbon electrodes (graphite rods from old torch cells can be used for this purpose) into these rubber stoppers. Connect the electrodes to a 6V battery.

Fill the cup with water so that the electrodes are immersed. Add 2 – 3 mL of dilute sulphuric acid. Dilute sulphuric acid is added to increase the ionisation of water and thereby increase its electrical conductivity. Take two test tubes filled with water and invert them over the carbon electrodes. Turn on the switch and leave the experimental setup undisturbed for some time. You will observe bubbles forming at both the electrodes. After some time, remove the test tubes carefully.

ELECTROLYTES
Electrolytes are substances that undergo chemical changes when electricity passes through them.

ELECTROLYSIS
Electrolysis is the process by which an electrolyte undergoes chemical changes when electricity is passed through it.
Examine the figure that represents the electrolytic process.

Ions are free to move in the liquid state or in an aqueous solution of an electrolyte. These ions are responsible for the electrical conductivity in the electrolyte.

• Acids (like HCl, H₂SO₄, HNO₃, CH₃COOH) contain free ions in aqueous solutions (when mixed with water).
• Alkalies (like KOH, NaOH) also contain free ions in aqueous solutions.
• Salts (NaCl, KCl,.) contain free ions in their aqueous solution and molten state.
  For example, sodium chloride dissociates into Na⁺ and Cf ions in the molten state or in the aqueous solution.

ELECTRODES

• Electrodes are conductors through which electricity enters or leaves the electrolyte.
• During electrolysis:
  • Anode is the electrode connected to the positive terminal of the battery.
  • Cathode is the electrode connected to the negative terminal of the battery.
• Reduction happens at the cathode.
• Oxidation happens at the anode.

ELECTROLYSIS OF MOLTEN SODIUM CHLORIDE
In the solid state, sodium chloride does not conduct electricity. The reason is that, though the ions can vibrate about their fixed positions, they are not free to move. However, molten NaCl is a good conductor because its ions move freely.

Examine the figure given below.

Two graphite electrodes are connected to a direct current (DC) source through wires. They are dipped in a vessel containing molten sodium chloride. When electricity is passed through them, the following observations can be made.
1. Chlorine gas (Cl₂), having a pale green colour, is liberated at the anode.
2. Silvery molten sodium metal (Na) is formed at the cathode.
a) What are the ions in molten sodium chloride?
Answer:
The ions present are sodium cations (Na⁺) and chloride anions (Cl^–). When sodium chloride (NaCl) is in a molten (liquid) state, its ionic bonds are broken, allowing these ions to move freely.

b) What is the chemical reaction taking place at the anode?[Oxidation/Reduction|
Answer:
Oxidation occurs at the anode (the positive electrode). The chloride anions (Cl^–) lose an electron to form chlorine gas (Cl₂).
Write the equation of the reaction. 2Cl^– → Cl₂ + 2e^–

c) What is the chemical reaction taking place at the cathode? [Oxidation/Reduction]
Answer:
Reduction occurs at the cathode (the negative electrode). The sodium cations (Na⁺) gain an electron to form molten sodium metal (Na).
Write the equation of the reaction. Na⁺ + e^– → Na

d) What are the products obtained as a result of the electrolysis of molten sodium chloride?
Answer:
The products are chlorine gas (Cl₂) at the anode and molten sodium metal (Na) at the cathode.

ELECTROLYSIS OF AQUEOUS SODIUM CHLORIDE
The figure below representing the electrolysis of aqueous sodium chloride solution.

When a suitable voltage is applied across the electrodes of the cell, the following observations can be made.

1. H₂ gas is liberated at the cathode. If phenolphthalein indicator is present in the solution, the solution around the cathode turns pink. That is, the solution becomes basic in nature.

2. Cl₂ gas is liberated at the anode.
At the anode, chloride ions are getting oxidised to Cl₂ gas.
a) Write the equation of the reaction.?
Answer:
2Cl^– → Cl₂ + 2e^–

b) Based on the reactivity series, which has greater oxidising tendency-sodium or hydrogen?
Answer:
Hydrogen has a greater oxidising tendency. In the reactivity series of metals, hydrogen is below sodium, which means it is less reactive.

c) If so, which of the following is getting reduced at the cathode, Na⁺ or H₂O?
Answer:
At the cathode, H₂O molecules are reduced to produce H₂ gas and OH^– ions.
2H₂O + 2e^– → H₂ + 2OH^–
As a result of the processes taking place in the cell gases such as H₂, Cl₂ and an aqueous solution of NaOH are formed. This aqueous solution can
basic in nature. be evaporated to produce solid NaOH.

APPLICATION OF ELECTROLYSIS

1. Production of metals
   Metals like sodium, potassium, calcium and aluminium are produced by the electrolysis of some of their compounds.
2. Production of nonmetals
   Electrolysis is used in the industrial production of nonmetals like hydrogen, oxygen and chlorine.
3. Manufacture of compounds
   Electrolysis is used in the production of sodium hydroxide and potassium hydroxide.
4. Electroplating
   Gold plated jewellery, silver plated utensils, chromium plated iron objects etc are produced through electroplating.
5. Purification of metals
   Electrolysis is useful in the purification of metals such as copper, gold etc.

ELECTROCHEMICAL CELLS AS ENERGY SOURCES
A cell is a device that helps to convert the energy released in a chemical reaction directly into electricity. Cells perform two main functions.

1. As portable sources of electrical energy:
   Examples range from the button cells, used in electronic watches, to the lead-acid cells used in vehicles.
2. As storage devices of electrical energy provided by an external source:
   Such cells can be used for powering electric vehicles, emergency power distribution and storing solar energy.

DIFFERENT TYPES OF CELLS
There are two main types of cells – Primary cells and secondary cells.
1. PRIMARY CELLS

• In primary cells, the cell becomes dead, when the electrical energy produced by chemical reaction is used up.
• These cells cannot be recharged and reused.
• Examples of primary cells are dry cells and button cells. [Dry cells are commonly used in clocks and button cells are used in watches]

2. SECONDARY CELLS

• A secondary cell can be recharged and used again.
• The most important type of secondary cell is the lead acid cell used in vehicles.
• The nickel-cadmium cell used in flashlights is also a secondary cell.

Uses of Lithium-ion batteries
Lithium-ion batteries are secondary cells that have become an integral part of our daily life.

• They are used as power sources for devices ranging from smartphones and laptops to electric vehicles.
• Lithium-ion batteries are used in portable electronic devices due to their high energy density, long lifespan and low self-discharge rate.
• Lithium-ion batteries are also used as satellite batteries, a crucial component in the energy systems of spacecrafts.

FUEL CELLS

• Fuel cells are a type of galvanic cell.
• They convert chemical energy produced by the combustion of fuel into electrical energy
• Fuels used include: – Hydrogen, Methane, Methanol
• They operate continuously as long as fuel is supplied.
• Main advantage: They produce electricity with high efficiency.

The comprehensive approach in SCERT Class 10 Physics Solutions Chapter 7 Mechanical Advantage in Action Important Questions with Answers ensure conceptual clarity.

SSLC Physics Chapter 7 Important Questions Kerala Syllabus

Mechanical Advantage in Action Class 10 Important Questions

Question 1.
If the toothed wheel attached to the axle is connected to the wheel attached to the engine as in the given figure, the speed of the vehicle …………………………….. .

(increases/deceases/ does not change)
Answer:
speed decreases

Question 2.
Which of the following have mechanical advantage equal to one.
a) Fixed pulley
b) Lemon squeezer
c) Common balance
d) forceps
Answer:
a) Fixed pulley and
c) Common balance

Question 3.
Some statements are given.
i) Mechanical advantage of first order lever is equal to one or greater than one or lesser than one.
ii) Mechanical advantage of second order lever is always less than one.
iii) Mechanical advantage of third order lever is always less than one.
iv) Mechanical advantage of third order lever is always greater than one.
Choose the correct option,
a) i & ii
b) i & iv
c) i & iii
d) none of these
Answer:
c) i & iii

Question 4.
If the toothed wheel attached to the axle is connected to the wheel attached to the engine as in the given figure, the efficiency of the vehicle to rotate ……………………………. .

(increases/deceases/does not change)
Answer:
increases

Question 5.
What is an example of a first-order lever in the human body?
Answer:
The neck is an example, where the skull (load) pivots on the atlas vertebra (fulcrum), and neck muscles (effort) control head movement.

Question 6.
Select the odd one.
(Scissors, Nut cracker, Common balance, seesaw)
Answer:
Nut cracker

Question 7.
Find the relation between the first word pair and complete the second pair.
Lemon Squeezer : Second order lever
Fishing pole : ……………………
Answer:
Third order lever

Question 8.
Give an example of a second-order lever used in everyday life?
Answer:
A nutcracker is a second-order lever, where the fulcrum is at one end, the load is in the middle, and the effort is applied at the handles.

Question 9.
What is an example of a third-order lever in the human body?
Answer:
The elbow joint is a third-order lever, where the fulcrum is the elbow, the effort is applied by the biceps muscle, and the load is in the hand or forearm.

Question 10.
Statement: The mechanical advantage of a second-order lever is always greater than one.
Reason: The effort arm and the load arm are equal. Which of the following is correct?
a) Both the statement and the reason are correct.
b) The statement is correct, but the reason does not justify the statement.
c) Both the statement and the reason are incorrect.
d) The statement is incorrect, but the reason is correct.
Answer:
b) The statement is correct, but the reason does not justify the statement.

Question 11.
What is the difference between a wedge and a screw?
Answer:
Both are simple machines. A wedge is a double inclined plane with a sharp edge . A screw can be considered as an inclined plane wrapped around a cylinder.

Question 12.
Why do second-order levers always have a mechanical advantage greater than 1?
Answer:
Because the effort arm (distance from fulcrum to effort) is always longer than the load arm (distance
from fulcrum to load), less effort is needed to lift the load, resulting in a mechanical advantage greater than 1.

Question 13.
A force of 30 N was applied on a nail puller to pull a nail. If the mechanical advantage of the nail puller was two, what would be the load applied by the nail?
Answer:
Mechanical advantage = Load /Effort
Mechanical advantage = 2
Effort = 30 N
Load = ?
Load = Mechanical advantage Effort
= 2 × 30 N
= 60 N

Question 14.
Say whether the following statements are true or false. Correct them if wrong.
a) If the effort comes in between the load and the fulcrum, it is a second order lever.
b) There is no gain in work by using simple machine.
Answer:
a) False
If the effort comes in between the load and the fulcrum, it is a third order lever.

b) True

Question 15.
What is a third-order lever, and how does it differ from other levers?
Answer:
In a third-order lever, the effort is applied between the fulcrum and the load. The load arm is longer than the effort arm, resulting in a mechanical advantage less than 1, meaning more effort is required.
Example: A pair of tweezers, fishing rod

Question 16.
What is a second-order lever, and how does it work?
Answer:
In a second-order lever, the load is located between the fulcrum and the effort. The effort arm is always longer than the load arm, providing a mechanical advantage greater than 1, making it easier to lift heavy loads.
Example: Wheelbarrow, nut cracker, lemon squeezer

Question 17.
Classify the following into those with a mechanical advantage greater than 1 and those less than 1: Nutcracker, fishing rod, lemon squeezer, bottle opener, wheelbarrow, forceps, tongs.
Answer:

Question 18.
Figure shows a lever.

a) Identify the type of lever shown in figure above? Give an another example for the same type of lever.
b) Explain about the type of lever identified.
c) How does it work?
Answer:
a) First-order lever
Example: Scissors

b) First-order lever has the fulcrum positioned between the effort and the load.

c) It works by pivoting around the fulcrum, allowing the effort to move the load. The mechanical advantage depends on the relative distances from the fulcrum to the effort and load.

Question 19.
How does the position of the fulcrum affect a lever’s function?
Answer:
The fulcrum’s position determines the lever’s mechanical advantage and function. In first-order levers, moving the fulcrum closer to the load increases mechanical advantage. In second-order levers, the fulcrum at one end maximizes force. In third-order levers, the fulcrum’s position enhances speed and range of motion at the cost of force.

Question 20.
What are the differences between first, second, and third order levers?
Answer:
First order lever: In a first order lever, fulcrum comes in between effort and load. The load can be equal to, lesser or greater than the effort. The mechanical advantage of a first order lever is equal to one or greater than one or lesser than one.

Second order lever: In a second order lever, the load is always more than the effort. The load comes in between effort and fulcrum. Mechanical advantage of a second order lever is always more than one.

Third order lever: In a third order lever, the load is always less than the effort. The effort comes in between fulcrum and load. Its mechanical advantage is always less than one.

Question 21.
Classify the following levers into first, second, and third order lever.
Nut cracker, Fishing pole, Scissors, Wheel barrow, Lemon Squeezer, Seesaw, Forceps, Common balance, Fixed pulley. Elbow, Ice tongs
Answer:
First order lever

• Scissors
• Common balance
• Fixed pulley

Second order lever

• Nut cracker
• Wheelbarrow
• Lemon Squeezer

Third order lever

• Fishing pole
• Forceps
• Elbow
• Ice tongs

Question 22.
Simple machines are basic mechanical devices that mechanical devices that make work easier.
a) What do you mean by simple machines?
b) There are mainly six types of simple machines. Which are they?
c) What is mechanical advantage (MA)?
d) Mechanical advantage of a wheel and axle system is ……………………………..
Answer:
a) Simple machines are devices that change the magnitude of the effect of force or the direction of the force or both. They are devices that make exertion easier.

b) Lever, Pulley, Wheel and axle, Inclined plane, Screw, Wedge

c) Mechanical advantage (MA) is the ratio of the load to the effort. It is a number indicating how many times of the load is the effort. Mechanical advantage is only a ratio. It has no unit.
Mechanical advantage, MA = \(\frac{\text { Load }}{\text { Effort }}\)

d) \(\frac{R(\text { Radius of wheel })}{r(\text { Radius of axle })}\)