Chapter 10 : The Nervous System - Selina Solutions for Class 10 Biology ICSE

Biology is one of the crucial subjects in ICSE Class 10. ICSE Class 10 Biology speaks about the cell as the basic unit of life, genes, and evolution and deals with how living organisms interact with the environment, including the behavior of living beings. TopperLearning is one of the premier online platforms which helps students of ICSE Class 10 to study various concepts in Biology.

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Chapter 10 - The Nervous System Excercise Ex. 1

Question 1

The insulating sheath covering the axon is called

(a) Plasmalemma

(b) Neurolemma

(c) Dura mater

(d) Pia mater

Solution 1

(b) neurolemma

Question 2
Which one of the following pairs of brain part and its function is not correctly matched?

(a) Cerebrum - memory

(b) Cerebellum - balance of body

(c) Medulla oblongata - controls activities of internal organs

(d) Pons - consciousness
Solution 2
(d) Pons - consciousness
Question 3
A mixed nerve is one which

(a) Carries sensation from 2 or more different sense organs

(b) Contains both sensory and motor fibres

(c) Has a common root but branches into two or more nerves to different organs

(d) Has two or more roots from different parts of brain
Solution 3
(b) Contains both sensory and motor fibres
Question 4

Reflex action is controlled by the

(a) brain

(b) spinal cord

(c) autonomic

(d) peripheral nervous system

Solution 4

(b) spinal cord

Question 5
Name the following:

(a) The fluid that is present inside and outside the brain.

(b) The junction between two nerve cells.

(c) The part of the brain which is concerned with memory.

(d) The part of the human brain which controls body temperature.
Solution 5
(a) Cerebrospinal fluid

(b) Synapse

(c) Cerebrum

(d) Hypothalamus
Question 6
Note the relationship between the first two words and suggest the suitable word/words for the fourth place.

(a) Stimulus: Receptor:: Impulse:_________

(b) Cerebrum: Diencephalon:: Cerebellum:_______

(c) Receptor: Sensory nerve:: Motor nerve:_______
Solution 6
(a) Stimulus: Receptor:: Impulse: Effectors

(b) Cerebrum: Diencephalon:: Cerebellum: Medulla oblongata

(c) Receptor: Sensory nerve:: Motor nerve: Effector
Question 7

Complete the following statements by choosing the correct alternative from the choices given in brackets:

(a) The dorsal root ganglion of the spinal cord contains cell bodies of (motor/ sensory/ intermediate) neurons.

(b) Cerebellum is the part of the brain which is responsible for

(i) Conducting reflexes in the body

(ii) Maintaining posture and equilibrium

(iii) Controlling thinking, memory and reasoning.

Solution 7

(a) Sensory

(b) Maintaining posture and equilibrium

(c) Spinal cord

Question 8
Mention, where in human body are the following located and state their main functions:

(a) Corpus callosum

(b) Central canal
Solution 8
(a) Corpus Callosum - It is located located in the forebrain. It connects two cerebral hemispheres and transfers information from one hemisphere to other.

(b) Central canal - It is located in centre of the spinal cord. It is in continuation with the cavities of the brain. It is filled with cerebrospinal fluid and acts as shock proof cushion. In addition, it also helps in exchange of materials with neurons.
Question 9
State whether the following statements are true (T) or false (F).

(a) The main component of the white matter of the brain is perikaryon. (T/F)

(b) The arachnoid layer fits closely inside the pia mater. (T/F)

(c) A double chain of ganglia, one on each side of the nerve cord belongs to the spinal cord. (T/F)

(d) Dura mater is the outermost layer of the meninges. (T/F)
Solution 9
(a) False

(b) False

(c) True

(d) True
Question 10

Differentiate between the following pairs with reference to the aspects in brackets.

(a) Cerebrum and cerebellum (function)

(b) Sympathetic nervous system and parasympathetic nervous system (overall effect on body)

(c) Sensory nerve and motor nerve (direction of impulse carried)

(d) Medulla oblongata and cerebellum (function)

(e) Cerebrum and spinal cord (arrangement of cytons and exons of neurons)

Solution 10

(a)

Cerebrum

Cerebellum

The cerebrum controls all voluntary actions. It enables us to think, reason, plan and memorize.

The cerebellum on the other hand maintains balance of the body and coordinates muscular activity.

 

 

 

 

 

(b)

Sympathetic Nervous System

Parasympathetic Nervous System

Sympathetic nervous system prepares the body for violent action against the abnormal condition.

Parasympathetic nervous system is concerned with re-establishing normal conditions after the violent act is over.

 

(c)

Sensory Nerve

Motor Nerve

Sensory nerve brings impulses from the receptors i.e. sense organs to the brain or spinal cord.

Motor nerve carries impulse from the brain or spinal cord to effector organs such as muscles or glands.

 

 

 

(d)

Medulla Oblongata

Cerebellum

Medulla oblongata controls the  activities of internal organs and many other involuntary actions

The cerebellum on the other hand maintains balance of the body and coordinates muscular activity.

 

(e)

Cerebrum

Spinal Cord

The grey matter containing cytons lies in the cortex (outer region) while the white matter containing axons lies in the medullary region (inner region).

The grey matter containing cytons lies in the medullary region i.e. inner side while the white matter containing axons lies in the cortex i.e. the outer region.

Question 11
Given below are two structures, write their special functional activity.

(a) Cerebellum and ____________.

(b) Myelin sheath and _____________.
Solution 11
(a) Cerebellum maintains balance of the body and coordinates muscular activity.

(b) Myelin sheath acts like an insulation and prevents mixing of impulses in the adjacent axons.
Question 12
Write the functions of the following:

(a) Synapse

(b) Association neuron

(c) Medullary sheath

(d) Medulla oblongata

(e) Cerebellum

(f) Cerebrospinal fluid
Solution 12
(a) Synapse: It is a gap between the axon terminal of one neuron and the dendrites of the adjacent neuron. It transmits nerve impulse from one neuron to another neuron.

(b) Association Neuron: It interconnects sensory and motor neurons.

(c) Medullary sheath: It provides insulation and prevents mixing of impulses in the adjacent axons.

(d) Medulla Oblongata: It controls activities of internal organs such as peristalsis, breathing and many other involuntary actions.

(e) Cerebellum: It maintains balance of the body and coordinates muscular activity.

(f) Cerebrospinal Fluid: It acts like a cushion and protects the brain from shocks.
Question 13

Explain the following terms:

(a) Motor nerve

(b) Autonomic nervous system

(c) Conditioned reflex

(d) Association neuron

(e) Gray matter

Solution 13

(a) Motor nerve: It contains motor fibres which carry impulses generated by the association neuron (brain or spinal cord) to the effector organs. Example: A nerve which arises from the brain and ends in the eye muscles is a motor nerve. It helps in rotating the eye.

(b) Autonomic nervous system: It is a part of the peripheral nervous system. It consists of a pair of chains of nerves and ganglia on either side of the backbone. It controls the involuntary actions of the internal organs.

(c) Conditioned reflex: It develops during life time due to experience or learning. It is brought about by the condition which is totally different from initial stimulus. Example: Salivation just by the smell of food.

(d) Association neuron: It is located in the brain and the spinal cord. It acts as a connecting neuron and interconnects the sensory and motor neurons.

(e) Gray matter: The cerebral cortex contains cell bodies of the neuron and is greyish in colour. It is called gray matter. The grey matter has many folds (i.e. gyri) and grooves (i.e. sulci). They increase the surface area to accommodate more nerve cells. A higher number of convolutions leads to greater intelligence.

Question 14
Rearrange the following in correct sequence pertaining to what is given within brackets at the end. (a) Effector --- sensory neuron --- receptor --- motor neuron --- stimulus --- central nervous system --- response (Reflex arc)

(b) Repolarization --- depolarization --- resting (polarized) (during conduction of nerve impulse through a nerve fibre)

(c) Axon endings --- nucleus --- dendrites --- axon ---perikaryon --- dendron (neuron structure)

(d) Diencephalon --- cerebellum --- medulla oblongata --- pons --- cerebrum --- mid brain (sequence of parts of human brain)
Solution 14
(a) Stimulus --- receptor --- sensory neuron --- central nervous system --- motor neuron --- effector --- response

(b) Resting --- depolarization --- repolarization

(c) Dendrites --- Dendron --- perikaryon --- nucleus --- axon --- axon endings

(d) Cerebrum --- diencephalon --- mid-brain --- cerebellum --- pons --- medulla oblongata
Question 15

(a) What is meant by reflex action?

(b) State whether the following are simple reflexes, conditioned reflexes or neither of the two.

(i) Sneezing

(ii) Blushing

(iii) Contraction of eye pupil

(iv) Lifting up a book

(v) Knitting without looking

(vi) Sudden application of brakes of the cycle on sighting an obstacle in front

Solution 15

(a) Reflex action  is an autonomic, quick and involuntary action in the body brought about by a stimulus.

(b)

Example

Type of Reflex

(i) Sneezing

Simple

(ii) Blushing

Simple

(iii) Contraction of eye pupil

Simple

(iv) Lifting up a book

 

Conditioned

(v) Knitting without looking

Conditioned

(vi)  Sudden application of brakes of the cycle on sighting an obstacle in front

Conditioned

Question 16
What are the advantages of having a nervous system?
Solution 16
The advantages of having a nervous system are as follows:

(a) Keeps us informed about the outside world through sense organs.

(b) Enables us to remember, think and reason out.

(c) Controls and harmonizes all voluntary muscular activities such as running, holding, writing

(d) Regulates involuntary activities such as breathing, beating of the heart without our thinking about them.
Question 17

Why is the spinal cord and the brain referred to as the central nervous system?

Solution 17

The brain and the spinal cord lie in the skull and the vertebral column respectively. They have an important role to play because all bodily activities are controlled by them. A stimulus from any part of the body is always carried to the brain or spinal cord for the correct response. A response to a stimulus is also generated in the central nervous system. Therefore, the brain and the spinal cord are called the central nervous system.

Question 18
What is the difference between reflex action and voluntary action?
Solution 18
Reflex actions are involuntary actions which occur unknowingly. Voluntary actions on the other hand are performed consciously.

Picking up an apple and eating it is an example of voluntary action whereas withdrawal of hand on touching a hot object is an example of reflex action.

Reflex Action

Voluntary Action

Reflex actions are involuntary actions which occur unknowingly.

Voluntary actions on the other hand are performed consciously.

Commands originate in the spinal cord, autonomic nervous system and a few in the brain as well.

Commands originate in the brain.

Question 19

Draw a labelled diagram of a myelinated neuron.

Solution 19

  

Myelinated Neuron

Question 20

During a street fight between two individuals, mention the effects on the following organs by the autonomous nervous system, in the table given below: (one has been done for you as an example).

 

Organ

Sympathetic System

Parasympathetic System

e.g. Lungs

Dilates bronchi and bronchioles

Constricts bronchi and bronchioles

1. Heart

 

 

2. Pupil of the eye

 

 

3. Salivary gland

 

 

Solution 20

 

Organ

Sympathetic System

Parasympathetic System

e.g. Lungs

Dilates bronchi and bronchioles

Constricts bronchi and bronchioles

1. Heart

Accelerates heartbeat

Retards heartbeat

2. Pupil of the eye

Dilates

Constricts

3. Salivary gland

Inhibits the secretion of saliva causing the drying of the mouth

Stimulates the release of saliva

 

Question 21
Two hungry boys (A and B) enter a restaurant and find a table decorated as follows:



Boy B starts salivating but not A. Explain the reason for this difference.
Solution 21
Salivation is an example of conditioned reflex that develops due to experience or learning. Saliva starts pouring when you chew or eat food. Therefore, this reflex will occur not just on the sight or smell of food. The brain actually needs to remember the taste of food. Boy B started salivating because he must have tasted that food prior unlike boy A.
Question 22
Given below are a few situations. What effective change will occur in the organ/body part mentioned and which part (sympathetic or parasympathetic) of the autonomic nervous system brings it about?

Situation

Organ/body part

Change/action

Part of autonomic nervous system involved

1. You have entered a dark room

Eye

 

 

2. Your body is consuming lot of glucose while running a race

Liver

 

 

3. You are chewing a tasty food

Salivary gland

 

 

4. You are running a race

Adrenal gland

 

 

5. You are retiring to bed for sleep

Heart

 

 

6. You are shivering in intense cold

Body hairs

 

 

Solution 22

Situation

Organ/body part

Change/action

Part of autonomic nervous system involved

1. You have entered a dark room

Eye

Pupil dilates

Sympathetic

2. Your body is consuming lot of glucose while running a race

Liver

Glycogen is converted into glucose in liver

Sympathetic

3. You are chewing a tasty food

Salivary gland

Salivation increases

Parasympathetic

4. You are running a race

Adrenal gland

Release of adrenaline and noradrenaline increases

Sympathetic

5. You are retiring to bed for sleep

Heart

Heart rate slows down

Parasympathetic

6. You are shivering in intense cold

Body hairs

Hair raised

Sympathetic

Question 23

Given below is the partially incomplete scheme of the components of peripheral nervous system. Fill up the blanks numbered (1)- (12):

 

  

 

Solution 23

 

Fill in the following information in the diagram.

1. Central Nervous System

2. Autonomic

3. 12

4. Spinal

5. 31

6. Neck

7. Waist

8. dilates

9. constricts

10. liver

11. neck 

12. sacral 

 

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