Class 10 Biology Chapter 4 Notes Kerala Syllabus Chemoreception in Organisms Questions and Answers

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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.

• Organisms belonging to the same species secrete it into the surroundings for communication. • It is used to mark a path and to attract mates.

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:

Plant Hormones	Function
Auxins	Increase the length of the stem, inhibit lateral bud growth, and regulate tropic movements, stimulate the formation of flowers 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.
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.
Abscisic acid	Maintains die 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.

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:

	Regulation of glucose
	Level increases	Level decreases
Hormone produced	Insulin	Glucagon
Producing cell	Beta cells of pancreas	Alpha cells of pancreas
Process taking place	Speeds up the entry of glucose into cells. In the liver and muscle cells, glucose is converted into glycogen.	Helps in the formation of glucose from glycogen and amino acids with the help of the liver.

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:

Hormone	Function
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.

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.