Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses

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Kerala State Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses

Sensations and Responses Questions and Answers

Question 1.
Kerala SSLC Class 10 Biology Chapter 1 Sensations and Responses 1
Children and other organisms have a variety of experiences? What are they?
Answer:

  • A child tasting a mango.
  • A snail withdrawing its body into the shell when it is touched.
  • Feel cold when washing face.
  • Birds are flying when making sound.

Question 2.
What are the factors to which children and organisms respond here?
Answer:

  • Touch
  • Sound
  • Light
  • Taste
  • Smell

Stimulus: The senses that evoke responses in organisms are called stimuli. These are two types, external and internal stimuli.

External stimuli: Sound, touch, heat, chemicals, pressure, cold, radiations.

Internal stimuli: Hunger, touch, infection, pressure variation, thirst, exhaust.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 1

  • Nerve cells or receptors that are capable of receiving stimuli from within the body and external environment are located in sense organs.
  • Nerve cells are capable of receiving stimuli from within the body and external environment. They also transmit messages to and from central nervous system and organs.
  • The function of the nervous system is to generate and coordinate responses according to internal and external changes.
  • The nervous system includes the brain, spinal cord, nerves, and receptors.

Neuron
A neuron has mainly the following parts a cyton (cell body), impulse receiving dendrons and branches of dendrons is dendrites, impulse transmitting axon and branches of axon is aconites, synaptic knobs for secreting neurotransmitter. In certain neurons, the nerve fibers are covered by myelin sheath, made up of white Schwann cells.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 2

Question 3.
Make a table which shows the function and peculiarities of different parts of nerve cell.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 3

Question 4.
Analyse figure given below and write inferences on myelin sheath.
Kerala SSLC Class 10 Biology Chapter 1 Sensations and Responses 2
Formation of myelin sheath:
Schwann cells, a part of nervous tissues repeatedly encircle the axon to form the myelin sheath. Myelin sheath in the brain and spinal cord is formed of specialized cells called Oligodendrocytes. The myelin sheath has a shiny white colour.

Functions of myelin sheath:

  • Provide nutrients and oxygen to the axon.
  • Accelerate impulses.
  • Act as an electric insulator.
  • Protects the axon from external shocks.
  • Gives white appearance (white matter) to the neural parts.

HSSLive.Guru

Question 5.
Differentiate between white matter and grey matter.
Answer:
The part of nerve, where myelinated neurons are present in abundance, is called as the white matter. The part of nerve where the cell bodies and nonmyelinated neurons are present is called as the grey matter.

Generation Of Impulses

The difference in the distribution of ions maintains positive charge on the outer surface and negative charge inside the plasma membrane of the receptor part of neuron. When stimulated, this ionic equilibrium (polarity) changes there and the outer surface becomes negatively charged and inner become positively charged. As a result, impulse generated. This charge difference stimulates its adjacent parts and similar changes occur there too. Thus a continuous flow of the impulse becomes possible.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 4

Charges on either side of the plasma membrane in a resting state:
Positive charge on the outer surface and negative charge inside the plasma membrane of the neuron.

Charges in the distribution of ions on both sides of the plasma membrane when it gets stimulated:
When stimulated, the ionic equilibrium in a particular part changes. As a result polarity changes and the outer surface becomes negatively charged while the inner surface becomes positively charged. The change does not persist for long.

Question 6.
How is the impulses transmit through the neurons?
Answer:
When impulses reach at the synaptic knobs, a chemical substance, known as neurotransmitter, released in the synaptic cleft. This neurotransmitter stimulates the adjacent dendrites to form new electric impulses.
Synapse:
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 5
The junction between neurons or between neurons and muscles or glands is known as the synapse. It helps to regulate the speed and direction of impulses. The impulses are transmitted across the synaptic cleft only through a chemical (neurotransmitter), secreted from the synaptic knobs.

This neurotransmitter stimulates the adjacent dendrites to form new electric impulses. Acetylcholine and dopamine are examples of neurotransmitters. Synapse helps to regulate the speed and direction of impulses.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 6
Question 7.
Complete the flow chart that shows the transmission of impulses through a neuron to other neurone.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 52Answer:
Impulse due to stimulus → dendrites → dendrons → cyton → axon → aconites → synaptic knob → secretion of neurotransmitter to the synaptic cleft → Stimulation in the adjacent dendrites → Impulse forms.

Nerves

Nerves are groups of axons or nerve fibers. They are covered by connective tissues. On the basis of function are further classified.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 8

Question 8.
Analyse table 1.1 and prepare notes in your science diary.

Nerves and their peculiarities

Functions

Sensory nerve (formed) of sensory nerve fibres carries impulses from various parts of the body to the brain and the spinal cord.
Motor nerve (formed of motor nerve fibres) carries impulses from brain and spinal cord to various parts of the body.
Mixed nerve (formed of sensory nerve fibres and motor nerve fibres) carries impulses to and from the brain and spinal cord

Answer:
Nerves:
Nerves are groups of axons or nerve fibers. They are covered by connective tissue.

Sensory nerve:
Carry impulses from various parts of the body to the brain and the spinal cord. Formed by the union of sensory nerve fibers.

Motor nerve:
Carry impulses from brain and spinal cord to various parts of the body. Formed by the union of motor nerve fibres.

Mixed nerve:
Formed by the union of sensory and motor fibres. Carry sensory impulses from the receptors to the brain or spinal cord. Carry motor impulses from brain or spinal cord to different parts of the body.

Nervous System

The nervous system consists of two parts, namely the central nervous system and the peripheral nervous system.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 9

Question 9.
Complete the Worksheet.
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 10

Brain

The brain contains the greatest number of neurons in the nervous system.
Protection of the brain:
The brain is protected inside a hard skull and is covered by a three-layered membrane, called the meninges. Cerebrospinal fluid, a fluid formed inside the meninges. It regulates the pressure inside the brain and to protect the brain from injuries.

Nourishment of the brain:
The cerebrospinal fluid formed from blood is reabsorbed into the blood. It provides nutrients and oxygen to the tissues of the brain.

Different parts of brain:
Human brain has outer cerebrum, cerebellum and medulla oblongata and inner thalamus and hypothalamus.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 11

Question 10.
Prepare a table showing different parts of brain, peculiarity and functions of each.
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 12

spinal cord

Question 11.
Structure of spinal cord
Answer:
Spinal cord, which is the continuation of medulla oblongata, is situated within the vertebral column and is covered by a three-layered membrane, called meninges. The outer part of spinal cord is white matter and inner is grey matter. The central canal at its center is filled with CSF. There are 31 pairs of spinal nerves arising from the spinal cord. A dorsal root and a ventral roof join to form a spinal nerve.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 13

Question 12.
How does the dorsal root differ from ventral root?
Answer:
Sensory impulses reach the spinal cord through the dorsal root. Motor impulses go out of the spinal cord through the ventral root.

HSSLive.Guru

Question 13.
Mention the functions of spinal cord.
Answer:

  • Transmitting impulses from different parts of our body to and fro the brain.
  • Coordinates the rapid and repeated movements during walking, running, etc.
  • Effects certain reflex actions.

Reflex Actions:
Reflex actions are the accidental and involuntary responses of the body in response to a stimuli. There are cerebral and spinal reflexes.

Reflex Arc:
Reflex arc is the pathway of impulses in the reflex action.

Question 14.
What are the parts that involve in a reflex arc?
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 14
A reflex arc involves.

  • stimulus receiving receptor.
  • sensory neuron.
  • inter neuron.
  • motor neuron.
  • effecting muscles.

Question 15.
Complete the flowchart of the pathway of impulse during a reflex action.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 15

Question 16.
What you mean by Cerebral reflex?
Answer:
A reflex under the control of the cerebrum is called cerebral reflex. Eg. We blink our eyes when light suddenly falls on our eyes.

Question 17.
There may be instances in your life when you felt sudden fear or sadness. Write down some of those experiences.
Answer:

  • Suddenly seeing a snake while walking.
  • On touching hot objects, the hand is withdrawn.
  • Withdrawal of the leg when a spine pierce into the feet.
  • When a housefly flies towards the eye, the eye blink.

Question 18.
What are the changes that take place in the body during emergency situations? Write them down in Table.
Answer:
During an emergency situation:

  • Heartbeat increases.
  • Breathing rate increases decreases.
  • Dilates eye pupil.
  • Salivary secretion decreases.

Autonomous nervous system:
The autonomous nervous system is composed of the sympathetic system and the parasympathetic system.
There are many activities which occur beyond our conscious area. Such activities are controlled by the autonomous nervous system. The endocrine system is also associated with the nervous system for performing this function.

Question 19.
Analyze illustration 1.5 to understand the actions of sympathetic and parasympathetic systems during emergency situations and complete table.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 16
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 17
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 18
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 19

Sensations and Responses Let Us Assess

Question 1.
The part of the brain which helps to maintain body balance,
a) Cerebrum.
b) Cerebellum.
c) Medulla oblongata.
d) Thalamus.
Answer:
b) Cerebellum.

HSSLive.Guru

Question 2.
Identify the relationship and fill in the blanks.
Irregular flow of charge in the brain: Epilepsy.
Decreased production of dopamine:….?
Answer:
Parkinsons.

Question 3.
Analyse the following instances and answer the questions.
1) a thorn accidentally pierce the foot.
2) the leg is withdrawn.
3) the thorn is taken out slowly.
a) Write the stimuli and response.
b) Which is the conscious response?
c) Was the leg withdrawn after sensing the pain? Which action took place there? Prepare an illustration showing the parts through which the impulses transmitted.
Answer:
a) A thorn accidentally pierce the foot (stimulus) and the leg is withdrawn (response).
b) The thorn is taken out slowly.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 20
c) No, reflex action.
Stimulus → Receptor → Sensory nerve → Interneuron → motor nerve → related muscle → Withdrawl of leg.

Sensations and Responses Extended Activities

1. Prepare a model of the human brain using locally available materials and exhibit in the class.
(Hint:- Paper/Pulp)
2. Prepare the script of a short play which contains the methods of first aid to be given to people who have met with accidents and present it.

Sensations and Responses More Questions and Answers

Question 1.
Select the suitable code from the indicators and write them on the basis of correct features in the given boxes.
Cerebrum – CRB
Cerebellum – CRZ
Medulla oblongatas – MOG
Hypothalamus. – HYP
Thalamus – THL
Answer:
1. The part that provide awareness of vision, hearing, smell, tastes, touch, heat. (CRB)
2. Co-ordinates muscular activities and maintains equilibrium of the body. (CRL)
3. Plays a major role in the maintenance of homeostasis. (HYP)
4. Controls involuntary actions like heartbeat, breathing, etc. (MOG)
5. Relay station of impulses to and fro the cerebrum. (THL)
6. Centre of thought, intelligence, memory and imagination. (CRB)
7. The second-largest part of the brain. (CRL)
8. The rod-shaped medulla oblongata is seen below the cerebrum. (MOG)
9. Greymatter is seen in the external cortex and white matter is seen in the internal medulla. (CRB)
10. Part that controls pituitary gland. (HYP)

Question 2.
Classify the following items as external stimulus and internal stimulus.
Sound, hunger, touch, heat, chemicals, pressure, infection, pressure variation, thirst, cold, exhaust, radiations.
Answer:
External stimuli: Sound, touch, heat, chemicals, pressure, cold, radiations.
Internal stimuli: Hunger, touch, infection, pressure, variation, thirst, exhaust.

HSSLive.Guru

Question 3.
Suppose that the formation of CSF ceases in meninges, how would be the aftereffect of this?
Answer:
When the formation of CSF ceases, it will adversely affect our nervous system, because, CSF provides nutrients and oxygen to brain tissues, regulates the pressure inside the brain and also protects brain from injuries.

Question 4.
Any mild injury to the medulla oblongata may lead to sudden death. Why?
Answer:
Medulla oblongata controls involuntary actions like heartbeat and breathing. Any mild injury to medulla oblongata results disfunctioning of breathing and heartbeat and may lead to death.

Question 5.
A person could not walk easily after drinking alcoholic beverages. Can you say why?
Answer:
Alcohol is affected the normal functioning of his cerebellum, which maintains equilibrium of the body through muscular coordination. So he could not walk easily.

Question 6.
After a road accident, a person lost his memory for a few days. In which part of his brain got injured?
Answer:
Cerebrum.

Question 7.
List out the physiological changes that may occur when a boy facing the audience during a competition.
Answer:

  • Increases the rate of heartbeat.
  • Dilation of trachea / Increases breathing.
  • Conversion of glycogen to glucose.
  • Secretion of hormones increase.
  • Decrease in the secretion of saliva.

Question 8.
Rajesh is taking his food watching blood cold scenes of a film on TV. Will this affect his digestion? Make inferences in connection with his sympathetic and parasympathetic system.
Answer:
When excitement occurs, sympathetic nervous system enhances the physiological activities, except activities related to digestion. Since sympathetic system worked in Rajesh, it will affect his digestion and related activities.

Question 9.
Find out the odd one. Write down the common feature of others: Intelligence, Hearing, Breathing, Imagination. (Model 2016)
Answer:
Breathing. All others are controlled by the cerebrum.

Question 10.
Find out the relationship between the pair of words and fill up the blanks.
a) Relay of impulses: thalamus
…………… : hypothalamus
Answer:
Homeostasis

HSSLive.Guru

Question 11.
Find out the odd one and identify the common features of others: Dendrite, Acetyl Choline, Axon, Synaptic knob. (March 2016)
Answer:
Acetyl Choline. Others are parts of neurons.

Question 12.
Which is related to Alzheimer’s disease from those given below? What is the chief symptom of the disease?
a) Degeneration of specific ganglion.
b) Accumulation of an insoluble plaque in nervous tissue.
c) Irregularity in the electric Impulse in the brain. (March 2016)
Answer:
b) Accumulation of an insoluble protein in nervous tissue.

Question 13.
Tabulate the following activities based on the type of nervous system that controls, and give proper headings.
a) Recognize smell of flowers.
b) Taking decisions at the emergency situations.
c) Rate of heartbeat increases at times of crisis.
d) Production of hormone decreases after overcoming the crisis. (March 2016)
Answer:
a) Central nervous system
b) Autonomous nervous system
c) Sympathetic nervous system
d) Parasympathetic nervous system

Question 14.
Find out Sword pair relation’ and fill in the blanks,  (Model 2015)
a) Cerebellum: Equilibrium.
…….. : Functions as the relay station of impulses.
Answer:
a) Thalamus.

Question 15.
Some indications of a disease are given below.  (Model 2015)
1) Loss of complete memory, even the memory regarding the day, date, etc.
2) The patient becomes unaware of his actions.
3) It is common among aged people.
a) Identify the disease.
b) How is it caused?
Answer:
a) Alzheimer’s disease.
b) Continuous degeneration of neurons due to plaque by the accumulation of an insoluble protein.

Question 16.
Find out the relationship between the pair of words and fill up the blanks.  (Model 2015)
Cranial nerve : Communication from Brain to organ.
………. : Communication from Spinal cord to organ.
Answer:
Spinal Nerve.

Question 17.
Find out the odd one and comment on the common feature of others.  (Model 2014)
a) Dendron, Axon, Ampulla, Dendrite, Aconite.
b) Seeing beautiful cinema, Thinking, Hearing melodious song, Sudden withdrawal of legs while stepping on fire accidentally, Sensing the taste of sweets.
Answer:
a) ampulla, others are parts of neurons.
b) Sudden withdrawal of legs while stepping on fire accidentally, others are conscious activities.

Question 18.
List of various physiological activities in human body which are under the control of 2% autonomous nervous system are given below. Group them into actions of sympathetic system (Group A) and parasympathetic system (Group B).
a) Pupil dilates.  (Model 2014)
b) Urinary bladder contracts.
c) Trachea dilates.
d) Function of the stomach is stimulated.
e) Secretion of saliva increases.
f) Glycogen is converted into glucose.
g) Peristalsis slows down.
h) Rate of heartbeat decreases.
Answer:
Sympathetic System:
a) Pupil dilates.
c) Trachea dilates.
f) Glycogen is converted to glucose.
g) Peristalsis slow down.

Parasympathetic System:
b) Urinary bladder contracts.
d) function of stomach is stimulated.
e) Secretion of saliva increases.
h) Rate of heartbeat decreases.

Question 19.
Symptoms of a disease related to nervous system is given below.  (Model 2014)
a) Tremor due to the irregular involuntary movement of muscles.
b) Uncontrolled flow of saliva.
c) Loss of balance of the body.
i) Identify this disease and write down its name.
ii) What is the cause of this disease?
Answer:
i) Parkinson disease.
ii) Deficiency of a neurotransmitter dopamine.

Question 20. )
Redraw the picture and answer the following questions.  (Model 2014)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 21
a) Identify and label the parts according to the functions given below:
i) the part which maintains balance and equilibrium of the body?
ii) the part which controls heartbeat.
iii)the part which controls voluntary activities.
b) Write one more function for each of these three identified parts.
Answer:
a) Redrawing figure:
b) i) Cerebellum-co-ordinating muscular activities.
ii) Medulla oblongata – Controls breathing.
iii) Cerebrum – center of intelligence.

Question 21.
Select the odd one. Write the common feature of others.  (March 2013)
Axon, Nephron, Dendron, Dendrite.
Answer:
Nephron. Others are parts of neuron.

Question 22.
Radha is moving away with fear from a snake.  (March 2013)
a) State what happens to the functioning of following organs?
Heart, Pupil, Trachea and Liver
b) Which nervous system is activated during such emergency situation?
Answer:
a) Rate of heartbeat increases, Pupil dilates, Trachea dilates, Glycogen is converted into glucose within liver,
b) Sympathetic system.

Question 23.
Find out ‘Word pair relation’ and fill in the blanks.  (March 2013)
Eye – Vision
Cerebellum –
Answer:
To maintain body balance.

HSSLive.Guru

Question 24.
Find the odd one. Write down the common features of others.  (March 2013)
Epilepsy, Parkinson’s disease, Mumps, Alzheimer’s disease.
Answer:
Mumps – All others are the diseases caused by any kind of problems in brain.

Question 25.
a) Which is the part of nervous system excited during emergency situation?  (Model 2012)
b) How does this system acts on the following internal organs?
Heart, Liver, Urinary bladder and Eye.
Answer:
a) Sympathetic nervous system
b) Heart – Rate of heartbeat increases, Liver Glycogen is converted into glucose, Urinary bladder – Regains its original state, Eye – Pupil dilates.

Question 26.
Find out the odd one. Justify your answer.  (Model 2012)
a) Blinking of eyes in intense light.
b) Withdrawing hands-on touching hot object.
c) Withdrawing of legs when contact with thorns.
Answer:
a) Blinking of eyes in intense light. This is cerebral reflex. Others are spinal reflexes.

Question 27.
Find out ‘word pair relation’ and fill up.  (Model 2012)
Cerebrum: Thought
Cerebellum :
Answer:
Equilibrium

Question 28.
Hypothalamus has an important role in maintaining homeostasis. Analyze this statement and note down 4 ideas to justify your views.  (March 2012)
Answer:
Hypothalamus produces certain neurosecretory hormones which influence the production of various stimulating hormones secreted by the pituitary gland. These hormones, in turn, stimulate the production of hormones of certain other important endocrine glands. Pituitary glands stimulate the glands to produce the hormones only according to the need of the body.

So hypothalamus indirectly helps in maintaining homeostasis. For example, during summer when water has to be retained in the body vasopressin is produced which will enhance the reabsorption of water from urine and they maintain the water level in the body. Calcium level is also maintained by the decrease and increase production of calcitonin and parathormone. In short

  • Changes in the internal environment affects the rhythm of life activities.
  • Secretion of hormones is increased or decreased according to the changes
  • Life activities are regularised this way.
  • Thus hypothalamus prepares the body to overcome different situations and maintain a normal balance.

Question 29.
Segregate the appropriate statements from column.  (March 2012)
(A) as the functions of sympathetic.
(B) and Parasyampathic.
(C) nervous system.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 22
Answer:
B. Sympathetic nervous system:

  • Decreases abdominal activities.
  • Conversion of glycogen to glucose.
  • Peristalsis slows down.
  • Increases breathing.

C. Parasympathetic nervous system:

  • Pupil constricts
  • Secretion of saliva increases

Sensations And Responses SCERT Questions and Answers

Question 1.
The parts of a reflex arc are illustrated in the form of a flow chart. Fill in the blank portions and complete the flow chart.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 23
Answer:
A) Receptor.
B) Sensory neuron.
C) Intemeuron.
D) Motor neuron.

HSSLive.Guru

Question 2.
Appu was taken by fear, on seeing a snake on his way to school and ran back.  (Question Pool – 2017)
i) Which part of the autonomous nervous system controlled the body activities of Appu in the above situation?
ii) What are the changes that take place in the intestine and eye during the above situation?
Answer:
i) Sympathetic system.
ii) Peristalsis in the intestine slows down pupil dilates.

Question 3.
Which of the following activities take place under the control of the parasympathetic system?  (Question Pool – 2017)
Urinary bladder contracts, glycogen is converted to glucose, Gastric activities slow down, production of saliva increases.
Answer:
Urinary bladder contracts.
Production of saliva increases.

Question 4.
The brain contains a fluid which is formed from and reabsorbed into the blood,  (Question Pool – 2017)
a) Identify the fluid.
b) What are the functions of that fluid?
Answer:
a) Cerebrospinal fluid.
b) Provides nutrients and oxygen to brain tissues, protects the brain from injuries.

Question 5.
Some of the activities of the autonomous nervous system are given below. Analyze the activities and tabulate them under appropriate headings.  (Question Pool – 2017)
a) Pupil dilates.
b) Production of hormones decreases.
c) Converts glucose to glycogen.
d) Peristalsis slows down.
Answer:

Sympathetic system Parasympathetic system
a) Pupil dilates c) Converts glucose to glycogen
d) Peristalsis slows down d) Production of hormone decreases

Question 6.
A synapse is only the junction between two neurons. Do you agree with this statement? Why?  (Question Pool – 2017)
Answer:

  • Don’t agree.
  • It is the junction – between two neurons.
  • between a neuron and a muscle cell.
  • between a neuron and a glandular cell.

Question 7.
Write down the action of the parasympathetic and the sympathetic system in the following organs.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 24
Answer:
a) Pupil constricts.
b) Pupil dilates.
c) Heartbeat becomes normal.
d) Heartbeat increases.

Question 8.
One of the components of the nervous system is illustrated below. Fill in the blanks appropriately.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 25
Answer:
A. Cranial nerves.
B. 31 pairs.
C. Autonomous nervous system.
D. Sympathetic system.

Question 9.
The dorsal root and the ventral root play a significant role in the transmission of impulses between spinal cord and different parts of the body. Do you agree with this statement? Justify.  (Question Pool – 2017)
Answer:

  • Yes. Sensory impulses reach the spinal cord through the dorsal root.
  • Motor impulses go out of the spinal cord to different parts of the body through ventral root.

Question 10.
All reflex actions take place under the control of the spinal cord. Evaluate the statement and justify with suitable examples.  (Question Pool – 2017)
Answer:

  • All reflex actions are not under the control of the spinal cord.
  • Cerebral reflex / some reflex actions are under the control of the cerebrum.
    Eg. Weblink our eyes when light suddenly falls on eyes/any cerebral reflex.

Question 11.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 26
The causes of diseases related to the nervous system in two individuals X and Y are given above.  (Question Pool – 2017)
i) Identify the diseases?
ii) The deficiency of which neurotransmitter causes disease in Y?
Answer:
i) X-Alzheimer’s.
ii) Dopamine.

Question 12.
The flow chart given below indicates the transmission of impulse from one neuron to another. Complete the flow chart using the data given in the box.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 27
Answer:
A. Dendron.
B. Cell body.
C. Axon.
D. Aconite.
E. Synaptic knob.
F. Neurotransmitter.

Question 13.
Examine the picture given below.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 28
a) Identify A and B.
b) What is the role of A in the transmission of electric impulses?
Answer:
a) A – Myelin sheath.
B – Schwann cell.
b)1. accelerates impulses.
2. act as an electric insulator.
3. provides nutrients and oxygen to axon.

Question 14.
The illustration of a nerve based on its function is given below.  (Question Pool – 2017)
a) Identify the nerve depicted in the illustration.
b) Identify the nerve that carries impulse to and from A and B?
Answer:
a) Sensory nerve.
b) Mixed nerve.

HSSLive.Guru

Question 15.
The sympathetic nervous system stimulates all body activities. Its activity helps the body to overcome emergency situations.  (Question Pool – 2017)
Do you agree with the statement? Justify your answer by citing suitable examples.
Answer:

  • Agree partially.
  • Sympathetic system enables body to overcome emergency situations.
  • Sympathetic system slows down certain body activities.
  • Eg. Production of saliva decreases/slows down peristalsis. Slows down gastric activities.

Question 16.
The illustration given below indicates the transmission of impulses from one neuron to another. Observe the illustration and answer the following question.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 29
Identify the part in the illustration.
Identify the chemical substance which is secreted from A. Give one example for this chemical substance.
Answer:
a) Synapse.
b) Neurotransmitters, Acetylcholine / Dopamine.

Question 17.
Analyze the illustration of impulse transmission through axon and answer the following questions.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 30
a) What are the changes that take place in illustration B when compared to A? Give reason for this change.
b) Explain how this change brings about the transmission of impulses through axon.
Answer:
a) When stimulated, ionic equilibrium in the particular part changes and the outer surface of the plasma membrane of axon becomes negatively charged while the inner surface becomes positively charged.
b)1. These changes generate impulses.
2. The momentary charge difference in the axon stimulates its adjacent parts.
3. Similar changes occur there also.
4. Impulses get transmitted through axon.

Question 18.
Complete the following illustration.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 31
Answer:
A. Central canal.
B. Sensory impulses.
C. Ventral root.

Question 19.
The disease symptoms of two individuals are given below.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 32
a) Identify the diseases of individuals A and B.
b) Explain the causes of diseases in individual A.
Answer:
a) A-Alzheimers.
B – Parkinsons.
b)1. Accumulation of an insoluble protein in the neural tissues of the brain.
2. Neurons get destroyed.

Question 20.
Mohan lost his memory and was partially paralyzed after he met with an accident.  (Question Pool – 2017)
a) Which part of Mohan’s brain was affected?
b) How is the brain protected?
Answer:
a)1. Cerebrum.
2. Skull.
3. Meninges.
4. Cerebrospinal fluid.
b) The brain is protected inside a hard skull and is covered by a three-layered membrane called the meninges. Cerebrospinal fluid a fluid formed inside the meninges also protects the brain.

HSSLive.Guru

Question 21.
Observe the picture and answer the following.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 33
a)Identify A.
b)What are the peculiarities of the impulses which are transmitted through the dorsal root and the ventral root?
Answer:
a) A – central canal.
b)1. Dorsal root – sensory impulses.
2. Ventral root – motor impulses.

Question 22.
The following figure shows the distribution of ions on either side of the plasma membrane of the axon. Analyze the figure and answer the following.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 34
a) Why is there a difference in charge distribution on either side of the plasma membrane?
b) What changes do the stimulus create in the charges on either side of the plasma membrane? How do these charges get transmitted through the axon as impulses?
Answer:
The difference in the distribution of ions.

  • When stimulated, in that particular part, the outer surface of the plasma membrane becomes negatively charged while the inner surface becomes positively charged.
  • The momentary charge difference stimulates its adjacent parts and similar.

Question 23.
Draw the diagram and label the following parts.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 35
a) The part which secretes acetylcholine.
b) The part which receives impulses from the adjacent neuron.
c) The part which carries impulses from the cell body to outside.
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 36
a) Synaptic knob.
b) Dendrite.
c) Axon.

Question 24.
Draw the diagram and label the following parts.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 37
a) The part that helps in the maintenance of homeostasis
b) That acts as relay station of impulses to and from the cerebrum.
c) The second-largest part of the brain.
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 38
a) Hypothalamus.
b) Thalamus.
c) Cerebellum.

Question 25.
Identify the correct statements from those given below:  (Question Pool – 2017)
i) The central nervous system consists of the brain and the spinal cord.
ii) The peripheral nervous system consists of 31 pairs of cranial nerves and 12 pairs of spinal nerves.
iii) The sympathetic system and the parasympathetic system are parts of the central nervous system.
iv) The autonomous nervous system which is a part of the peripheral nervous system helps to overcome the emergency situations.
Answer:
Correct statements
(i),
(iv).

Question 26.
Identify the odd one. What is common about others?  (Question Pool – 2017)
a) Touch, light, hunger, sound.
b) Brain, gland, nerves, spinal cord.
c) Breathing, sight, intelligence, hearing.
Answer:
a) hunger – others are external stimuli.
b) gland – others are parts of nervous system.
c) breathing – others are controlled by cerebrum.

Question 27.
Box A and Box B contains the parts of the brain and related information respectively. Analyze the information in the boxes and complete the table as per the model “cited”.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 39

Part

Hypothalamus

Location

Situated just below the thalamus

Function

Maintains homeostasis

Thalamus
Cerebellum
Medulla
oblongata

Answer:

Part Location Function
Thalamus Situated below the cerebrum relay station of impulse
Cerebellum behind the cerebrum maintains equili­brium of the body
Medulla oblongata seen as a rod-shaped structure near the cerebellum controls involuntary actions

Question 28.
Observe the illustration and answer the questions.  (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 40
a) Which action does the illustration depict?
b) Identify A, Band C.
Answer:
a) reflex action.
b) A – Sensory nerve.
B – Motor nerve.
C – Interneuron.

Question 29.
Identify the word pair relationship and fill in the blanks:  (Question Pool – 2017)
i) Sensory nerves: Carries impulses to the spinal cord.
………….. : Carries impulses from the brain to various parts of the body.
ii) Skull : Brain
…………… : Spinal cord
iii) Hypothalamus: Maintains homeostasis
…………… : Control center of involuntary actions.
iv) Dendrite: Receives impulses
…………… : Carries impulses outside
Answer:
i) Motor nerve.
ii) Vertebral column.
iii) Medulla oblongata.
iv) Axon.

HSSLive.Guru

Question 30.
Redraw the illustration and answer the questions given below.  (Orukkam – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 41
a) Identify the parts A, B, C?
b) Identify the part indicated by D?. How impulses are transmitted through this part?
c) Write the role of myelin sheath in the transmission of impulses?
d) The flowchart related to the transmission of impulses from one neuron to another is below. Complete the flowchart?
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 42
A- Dendrite.
B- Dendron.
C- Axon.
b) Synapse:
Neurotransmitter released by the synaptic knobs stimulate the dendrites of adjacent neurons to produce further impulse.
c) Myelin sheath increases the speed of impulse transmission. It also acts as an electric insulator.
d) A – Dendron.
B – Axon.
C – Aconite.
D – Neurotransmitter.

Question 31.
Balu: In the spinal cord and the cerebrum, white matter is seen outside and Greymatter is seen inside.  (Orukkam – 2017)
Ramu: In the cerebrum, the grey matter is seen outside and the white matter is seen inside, but in the spinal cord, the white matter is seen outside and the grey matter is seen inside.
In the group discussion related to the nervous system, Balu and Ramu said so.
a) Whose opinion do you agree with?
b) Explain white matter and grey matter?
Answer:
a) Ramu’s opinion
b)1. The part where myelinated neurons are present in abundance – white matter.
2. The part where cell body and non-myelinated. neurons are present – grey matter.

Question 32.
The statements related to the generation and transmission of impulses are given below. Select the letters related to each statement and label in the figures given below.  (Orukkam – 2017)
A. The charge difference in the axon membrane stimulates its adjacent parts and the part which is stimulated regain in its original state.
B. There exists a positive charge on the outer surface and negative charge inside the plasma membrane of the neuron.
C. The momentary charge difference proceeds, impulses get transmitted through axon.
D. When stimulated, the outer surface of the plasma membrane becomes negatively changed while the inner surface becomes positively charged.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 43
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 44

Question 33.
Redraw the picture, identify and label the parts which have the following functions.  (Orukkam – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 45
a) The part which controls involuntary actions.
b) The part which coordinates muscular activities.
c) The part which helps to feel senses.
d) The part which acts as the relay station of impulses.
e) The part which plays a major role in the maintenance of homeostasis.
B. Identify the parts of brain related to the following actions.

a) Maintains the equilibrium of the body
b) Controls breathing
c) The three-layered membrane which helps in the protection of brain.
d) The production center of oxytocin and vasopressin
e) Centre of thought, intelligence, and memory

Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 46
B. a – Cerebellum
b – Medulla oblongata.
c – Meninges.
d – Hypothalamus.
e – Cerebrum.

Question 34. (Orukkam – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 47
a) How these responses are known as?  (Orukkam – 2017)
b) Prepare a flowchart related to the pathway of impulses mentioned in A?
Answer:
a) Reflex Action
b) Receptor generates impulses → sensory neuron → Interneuron → Motor neuron → Related muscles.

Question 35.
Arrange the statements related to the actions of autonomous nervous system in the illustration given below. Give title to the illustration. (Orukkam – 2017)
A. The pupil in the eye dilates.
B. Urinary bladder contracts.
C. Glucose is converted to glycogen.
D. Gastric activities slow down.
E. The pupil constricts.
F. Gastric activities become normal.
G. Production of saliva decreases.
H. Glycogen is converted to glucose.
I. Production of saliva increases.
J. Urinary bladder retains to normal state.
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 48
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 49

Question 36.
Write the different types of nerves and their functions like the example given below.  (Orukkam – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 50.
Answer:
B. Sensory Nerve → Carries impulse to the brain and spinal cord from various sensory parts of the body.
C. Motor Nerve → Carries impulses from the brain and spinal cord to various parts of the body.

Question 37.
The symptoms of a disease that affecting nervous system is given below.  (Orukkam – 2017)
Loss of body balance, irregular movement of muscles, shivering of the body, profuse salivation
a) Identify the disease.
b) Write the causes of the disease.
c) Explain the other diseases that affecting nervous system with their cause and symptoms.
Answer:
a) Parkinsons
b) Degeneration of specific ganglia in the brain due to decreased production of dopamine.
c)1. Alzheimer’s: Loss of memory, Inability to recognize friends and relatives, Inability to do routine works.
2. Epilepsy: Continuous muscular contraction, frothy discharge from the mouth, clenching of teeth and falls unconscious.

HSSLive.Guru

Question 38.
Observe the figure and answer the questions given below.  (Orukkam – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 1 Sensations and Responses - 51
a) Identify the parts indicated as A, B, C?
b) Write the name of the fluid-filled in B?
c) How spinal cord is protected?
Answer:
a) A – Dorsal root.
B – Central canal.
C – Ventral root.
b) Cerebrospinal fluid.
c) Spinal cord is protected by a three-layered membrane meanings, filled with CSF, inside the spinal column.

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