Chapter 10 The Nervous System - Concise Biology Part II - Selina Solutions for Class 10 Biology ICSE

Question A.1

The insulating sheath covering the axon is called

(a) Plasmalemma

(b) Neurolemma

(c) Dura mater

(d) Pia mater

Solution A.1

(b) neurolemma

Question A.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 A.2

(d) Pons - consciousness

Question A.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 A.3

(b) Contains both sensory and motor fibres

Question A.4

Reflex action is controlled by the

(a) brain

(b) spinal cord

(c) autonomic

(d) peripheral nervous system

Solution A.4

(b) spinal cord

Question B.1

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 B.1

(a) Cerebrospinal fluid

(b) Synapse

(c) Cerebrum

(d) Hypothalamus

Question B.2

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 B.2

(a) Stimulus: Receptor:: Impulse: Effectors

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

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

Question B.3

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 B.3

(a) Sensory

(b) Maintaining posture and equilibrium

(c) Spinal cord

Question C.1

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

(a) Corpus callosum

(b) Central canal

Solution C.1

(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 C.2

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 C.2

(a) False

(b) False

(c) True

(d) True

Question C.3

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 C.3

(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 C.4

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

(a) Cerebellum and ____________.

(b) Myelin sheath and _____________.

Solution C.4

(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 C.5

Write the functions of the following:

(a) Synapse

(b) Association neuron

(c) Medullary sheath

(d) Medulla oblongata

(e) Cerebellum

(f) Cerebrospinal fluid

Solution C.5

(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 C.6

Explain the following terms:

(a) Motor nerve

(b) Autonomic nervous system

(c) Conditioned reflex

(d) Association neuron

(e) Gray matter

Solution C.6

(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 C.7

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 C.7

(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 D.1

(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 D.1

(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 D.2

What are the advantages of having a nervous system?

Solution D.2

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 D.3

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

Solution D.3

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 D.4

What is the difference between reflex action and voluntary action?

Solution D.4

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 D.5

Draw a labelled diagram of a myelinated neuron.

Solution D.5

Selina Solutions Icse Class 10 Biology Chapter - The Nervous System

Myelinated Neuron

Question D.6

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 D.6

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 E.1

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

Selina Solutions Icse Class 10 Biology Chapter - The Nervous System

Selina Solutions Icse Class 10 Biology Chapter - The Nervous System

Boy B starts salivating but not A. Explain the reason for this difference.

Solution E.1

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 E.2

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 E.2

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 E.3

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

Selina Solutions Icse Class 10 Biology Chapter - The Nervous System

Solution E.3

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

SELINA Solutions for Class 10 Biology Chapter 10 - The Nervous System

Chapter 10 - The Nervous System Exercise Ex. 1

SELINA Solutions for Class 10 Biology Chapter 10 - The Nervous System

Chapter 10 - The Nervous System Exercise Ex. 1

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