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

A. Multiple choice questions

1. The insulating sheath covering the axon is called

(a) Plasmalemma

(b) Neurolemma

(c) Dura mater

(d) Pia mater

Ans: (b) neurolemma

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

(a) Cerebrum - memory

(b) Cerebellum - the balance of body

(c) Medulla oblongata - controls activities of internal organs

(d) Pons - consciousness

Ans: (d) Pons - consciousness

3. A mixed nerve is one which

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

(b) Contains both sensory and motor fibers

(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 the brain

Ans: (b) Contains both sensory and motor fibers

4. Reflex action is controlled by

(a) Brain

(b) Spinal cord

(c) Autonomic nervous system

(d) Peripheral nervous system

Ans: (b) Spinal cord

5. Which one of the following is responsible for controlling the body temperature?

(a) Liver

(b) Lung

(c) Hypothalamus

(d) Spinal cord

Ans: (c) Hypothalamus 

6. Which of the following is absent in a neuron?

(a) Ribosome

(b) Centrosome

(c) Chromosome

(d) Lysosome

Ans: (b) Centrosome

7. The basic structural and functional unit of the brain is

(a) Nephron

(b) Nerve

(c) Spinal cord

(d) Neuron

Ans: (d) Neuron 

B. Very Short Answer Type

1. Name the following:

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

Ans: Cerebrospinal fluid.

(b) The junction between two nerve cells.

Ans: Synapse

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

Ans: Cerebrum

(d) The central space of the brain.

Ans: Ventricle

2. Note the relationship between the first two words and suggest the suitable word/words for the fourth place.

(a) Stimulus : Receptor :: Impulse : _________

Ans: (a) Stimulus : Receptor :: Impulse : Effector

(b) Cerebrum : Diencephalon :: Cerebellum : _________

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

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

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

(d) Axons : Nerve :: Cytons : _________

Ans: (d) Axons : Nerve :: Cytons : Nerve cells

(e) Cerebrum : Corpus callosum :: Cerebellum : _________

Ans: (e) Cerebrum : Corpus callosum :: Cerebellum : Pons

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.

Ans: Sensory is the correct answer here. 

(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.

Ans: (b) Maintaining posture and equilibrium

C. Short Answer Type

1. Mention, wherein the human body are the following located and state their main functions:

Ans:

(a) Corpus Callosum: The corpus callosum is located in the forebrain. It helps in connecting the two cerebral hemispheres and also transfers information from one hemisphere to another.

(b) Central Canal: The central canal is located in the center of the spinal cord. It is present in a continuous form with the cavities of the brain. It is filled with cerebrospinal fluid and acts as a shockproof cushion. Moreover, it also helps in the exchange of materials with neurons. 

2. State whether the following statements are true (T) or false (F).

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

Ans: False

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

Ans: False

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

Ans: True

(d) Dura mater is the outermost layer of the meninges. (T/F)

Ans: True

3. 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

Ans: The above answers are represented in the form of a table below: 

4. State the functions of the following:

(a) Association neuron

Ans: The association neuron helps in connecting neurons. The sensory and motor neurons are also connected to each other with the help of association neurons only. 

(b) Myelin sheath

Ans: The myelin sheath helps in insulating the impulses. It also helps in preventing the mixing of impulses to the adjacent axons. 

(c) Medullary sheath

Ans: The medullary sheath helps in providing insulation and prevents the mixing of impulses in the adjacent axons.

(d) Cerebrospinal fluid

Ans: The cerebrospinal fluid acts as a cushion and protects the brain from shocks and external damage from the environment. 

5. Rearrange the following in the 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)

Ans: (a) Stimulus --- receptor --- sensory neuron --- central nervous system --- motor neuron --- effector --- response

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

Ans: (b) Resting --- depolarization --- repolarization

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

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

(d) Diencephalon --- cerebellum --- medulla oblongata --- pons --- cerebrum --- midbrain (sequence of parts of human brain)

Ans: (d) Cerebrum --- diencephalon --- mid-brain --- cerebellum --- pons --- medulla oblongata

6. Name the following:

(a) Three types of neurons

Ans: (a) Three types of neurons:

1. Sensory neurons

2. Motor neurons

3. Association neurons

(b) Three types of nerves

Ans: (b) Three types of nerves:

1. Sensory nerves

2. Motor nerves

3. Mixed nerves

(c) Three main parts of the neuron

Ans: (c) Three main parts of the neuron:

1. Cyton

2. Dendrites

3. Axon

(d) Two major divisions of the nervous system

Ans: (d) Two major divisions of the nervous system:

1. Central nervous system

2. Peripheral nervous system

(e) Three layers of the meninges

Ans: (e) Three layers of the meninges:

1. Dura mater

2. Arachnoid

3. Pia mater

(f) Three main parts of the brain

Ans: (f) Three main parts of the brain:

1. Cerebrum

2. Cerebellum

3. Medulla oblongata

(g) Two parts of the autonomic nervous system

Ans: (g) Two parts of the autonomic nervous system:

1. Sympathetic nervous system

2. Parasympathetic nervous system

(h) Two types of reflexes

Ans: (h) Two types of reflexes:

1. Natural (inborn) reflex

2. Conditioned (acquired) reflex

7. Write the full forms of the following abbreviations:

(a) CSF

Ans: (a) CSF: Cerebrospinal fluid

(b) CNS

Ans: (b) CNS: Central Nervous System

(c) PNS

Ans: (c) PNS: Peripheral Nervous System

(d) ANS

Ans: (d) ANS: Autonomic Nervous System 

D. Descriptive type

1. Define the following terms:

(a) Neuron

Ans: Neurons are the structural and fundamental units of the nervous system. They are specialized to transmit information in the form of electrical impulses to different parts of the body.

(b) Nerve

Ans: The nerves are made up of nerve fibers (axons) of separate neurons, enclosed in a tubular sheath.

(c) Stimulus

Ans: An agent or the sudden change of the external or internal environment that results in a change in an organism or any of its body parts is called a stimulus.

(d) Synaptic cleft

Ans: The gaps between the axon terminals and the dendrites of another one or more neurons are called synaptic clefts.

(e) Reflex action

Ans: Reflex action is an automatic or quick or immediate involuntary action in the body brought about by a stimulus.

(f) Corpus callosum

Ans: Corpus callosum is a sheet of fibers connecting the two cerebral hemispheres.

2. Distinguish between the following pairs:

(a) Cerebrum and cerebellum (function)

Ans: (a) Differences between cerebrum and cerebellum (function):

(b) Sympathetic nervous system and parasympathetic nervous system (location and role)

Ans: Differences between the sympathetic nervous system and parasympathetic nervous system (location and role):

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

Ans: Differences between sensory nerve and motor nerve (direction of impulse carried):

(d) Cerebrum and spinal cord (arrangement of cytons and axons of neurons)

Ans: Differences between the cerebrum and spinal cord (arrangement of cytons and axons of neurons):

(e) Cranial nerves and spinal nerves (number in pairs)

Ans: Differences between cranial nerves and spinal nerves (number in pairs):

(f) Nerve impulse and flow of electricity (transmission and speed)

Ans: Differences between nerve impulse and flow of electricity (transmission and speed):

(g) Medulla oblongata and cerebellum (function)

Ans: Differences between medulla oblongata and cerebellum (function):

3. 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). 

Ans: 

4. Give reason:

(a) The brain and the spinal cord are referred to as the central nervous system.

Ans: (a) 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.

(b) Neurotransmitters are broken down by an enzyme just after passing an impulse from one neuron to the other.

Ans: (b) Neurotransmitters are broken down by an enzyme just after passing an impulse from one neuron to the other to make the synapse ready for the next transmission of the impulse.

5. What are the advantages of having a nervous system?

Ans: 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.

6. Draw a labelled diagram of a myelinated neuron.

Ans:

7. What is the difference between a reflex action and voluntary action?

Ans: Reflex actions are involuntary actions that 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.

E. Structure/application/skill type questions

1. Two hungry boys (A and B) enter a restaurant and see the menu. Boy B starts salivating but not A. Explain the reason for this difference.

Ans: Salivation is an example of a 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.

2. The diagram alongside shows a section of the human brain and its associated parts. Answer the questions that follow:

(a) Name the parts labelled 1, 2, 3, and 4.

Ans: (a) 1 - Cerebrum, 2 - Cerebellum, 3 - Pons, 4 - Medulla oblongata.

(b) Name the protective membranous covering of the brain. Also, mention its three layers.

Ans: (b) Meninges. The three layers of meninges are the dura mater, arachnoid and pia mater.

(c) Name the basic unit of the brain.

Ans: (c) Neuron/nerve cell.

(d) Write the important role of the part mentioned as 2.

Ans: (d) Cerebellum (part 2) coordinates a muscular activity and balance of the body. 

3. 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?

Ans:

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

Ans: 

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 - sacrum

Selina Concise Biology Class 10 ICSE Solutions for Chapter 10 - The Nervous System Key Features that Make it Easy to Study:

1. The language used is not on a level that students can’t understand and hence making it easy for them to read it once and understand.

2. The solutions are readily given in bullet forms that give a structured studying format.

3. Selina Concise Biology Class 10 ICSE Solutions for Chapter 10 - The Nervous System helps students learn the basics of the human nervous system and its functions.

4. The solutions provided in Selina Concise Biology Class 10 are in line with the syllabus and the question given in the textbook.