Selina Concise Class 10 Biology Chapter 10 The Nervous System Solutions
Chapter 10
The Nervous System
Progress Check
1) Solution:
i) Ans: Neurons (Nerve cell) are the structural and functional unit of nervous system.
ii) Ans: Nerve impulse is the wave of electrical disturbance that sweeps over the nerve cell.
iii) Ans: Axon is the long thread-like part of the nerve cell.
iv) Ans: Synapse is the point of contact (communication) between two nerve cells.
V) Ans: Nerve is the bundle of axon enclosed in a tubular sheath.
vi) Ans: Motor nerves carry impulses from the brain to a gland or muscle.
2) Solution:
i) Ans: Withdrawal of hand on touching a hot plate is a response.
ii) Ans: Seeing a green light turning into red at a road crossing before applying the brakes is categories in the stimulus.
iii) Ans: pain in the eye if something falls into it is the response.
Progress Check
1) Solution:
i) Ans: Brain and spinal cord are the parts of central nervous system.
ii) Ans: Cerebrum is the largest part of the brain.
iii) Ans: White matter consists mainly of axons.
iv) Ans: The part of the brain concerned with body balance is
2) Solution:
i) Ans:- Knee jerk is an reflect action in which two nerve cells along with their point of interaction i.e. synapse is involved.
ii) Ans:- It is conditioned reflex as it is an automatic response to a stimulus.
iii) Ans:- It is conditioned reflex as it does not occur naturally.
iv) Ans:- It is simple reflex since it is a natural phenomenon.
3) Solution:-
i) Ans: part 1 – White matter
Part 2 –Spinal cord
Part 3 – Dorsal root
Part 4 – Association neuron
Part 5 –Ventral root
Part 6 – Grey matter
Part 7 –
ii) Ans: Given diagram depicts phenomenon of ‘reflex action’.It is the involuntary response of effectors to the stimulus.
iii) Ans: The point of interaction between the two nerve cells is named as synapse.
iv) Ans: The parts like sensory neuron, dorsal ganglion, spinal nerve should be included to complete the pathway of the phenomenon.
Review questions:
Multiple choice type Solution:
i) Ans: b) neurolemma
The insulating sheath covering the axon is called neurolemma.
ii) Ans: d) pons – consciousness
The pair ‘Pons –consciousness’ is not matched because pons works together with medulla oblongata and it’s function is rapid eye movement.
iii) Ans: b) contains both sensory and motor fibres.
Therefore a mixed nerve is one which contains both sensory and motor fibres.
iv) Ans: b) spinal cord
Reflex action is controlled by spinal cord. Therefore option (b) is correct.
v) Ans: c) hypothalamus
Hypothalamus is responsible for controlling body temperature that’s why option (c) is correct option.
vi) Ans: c) chromosome
Centrosome is absent in neuron. Therefore correct option c.
vii) Ans: d) spinal cord
Option (d) is right option. Because
Neuron is The main structural and functional unit of brain .
Very short answer type solution-
1) Solution:
a) Ans: The fluid which is present inside and outside of the brain is the Cerebrospinal fluid.
b) Ans: Synapse is the junction between two nerve cells i.e. axon and dendrite.
c) Ans: Hypothalamusis the part of brain which is concerned with memory.
d) Ans: Central space of the brain is filled with cerebrospinal fluid.
2) Solution:-
a) Ans: Stimulus: receptor :: Impulse : Effectors
b) Ans: Cerebrum : diencephalon :: Medulla oblongata
c) Ans: Receptor : sensory nerve :: motor nerve : effector
d) Ans: Axons : Nerve :: Cytons : Neuron
e) Ans: Cerebrum :corpus callosum :: cerebellum :
3) Ans: The dorsal root ganglion of the spinal cord contains cell bodies of sensory neurons and axons of that sensory neurons travel in the spinal cord through dorsal root.
b) Ans: The part of the human brain which is responsible for the maintaining equilibrium and posture of the body is cerebellum.
c) SHORT ANSWER TYPE
1) Solution-
(a) Ans: The location of corpus callosum in human body is in the brain. The main function of corpus callosum is to transform information from one hemisphere to other hemisphere.
(b) Ans: Central canal is located in the spinal cord. It’s main function is to transport nutrients to the spinal cord. It carries cerebrospinal fluid which forms a medium for exchange of waste products, food and respiratory gases with neurons.
2) Solution:-
(a) Ans: False (The main component of the white matter of the brain is axon.)
(b) Ans: False (The arachnoid layer fits inside the dura mater)
(c) Ans: True (T) – A double chain of ganglia belongs to the spinal cord.
(d) Ans: True(T) – The outermost layer of meninges is dura mater.
3) Solution:-
(i) Ans: Sneezing is the simple reflex
(ii) Ans: Blushing is the simple reflex.
(iii) Ans: Contraction of eye pupil includes in simple reflex.
(iv) Ans: Lifting up a book is a conditioned reflex.
(v) Ans: It is a conditioned reflex.
(vi) Ans: Sudden application of brakes is conditioned reflex.
4) Solution:-
(a) Ans: Association neuron which are found in the central nervous system carry impulses from the motor neuron to the central nervous system. To the brain and the spinal cord.
(b) Ans: The main function of Myelin sheath is to protect nerves from electrical impulses. It also speed up the time taken toit for a nerve to traverse an axon.
(c) Ans: The function of medullary sheath is to protect and insulate certain nerve fibers.
(d) Ans: Cerebrospinal fluid is a shock proof cushion and the medium for exchange of food materials, respiratory gases and waste products with neurons.
5) Solution
(a) Ans: On the basis of reflex arc the sequence will be,
Stimulus -Receptor -Sensory neuron -Central nervous system – Motor neuron -Effector -Response.
(b) Ans: During conduction of nerve impulse through a nerve fibre the above sequence becomes,
Resting- Depolarization- Repolarization
(c) Ans: On the basis of Neuron structure the sequence will be,
Dendrites- Dendron- Perikaryon- Axon- Axon endings.
(d) Ans: Sequence of parts of human brain, Cerebrum- Diencephalon- mid brain- cerebellum- pons- Medulla oblongata
6) Solution-
(a) Ans: The three types of neurons are as follows,
- Sensory neurons
- Motor neurons
- Association or connecting neurons.
(b) Ans: Three kinds of nerves are as follows,
- Sensory nerves
- Motor nerves
- Mixed nerves
(c) Ans: Three main parts of the neuron are as follows,
- Cell body
- Dendrites
- Axon
(d) Ans: Two major divisions of the nervous system are,
- a) Central nervous system (made up of brain and spinal cord)
- b) Peripheral nervous system (made up of nerves)
(e) Ans: Three layers of the meninges are,
- Pia mater – Inner layer
- Arachnoid – Middle layer
- Dura mater – Outer layer
(f) Ans: Three main parts of the brain are,
- Cerebrum
- Brainstem
- Cerebellum
(g) Ans: Two parts of autonomic nervous system are,
- Sympathetic
- Parasympathetic
(h) Ans: Two types of reflexes are as follows,
- a) Natural or Inborn reflex
- b) Conditioned or Acquired reflex
7) Write full forms of the following abbreviations:
a) Ans: CSF – Cerebrospinal Fluid
b) Ans: CNS- Central nervous System
c) Ans: PNS – Peripheral Nervous System
d) Ans: ANS –Autonomic Nervous System
D) DESCRIPTIVE TYPE
1) Solution-
a) Ans: Neuron is the unit of the nervous system consists of brain, spinal cord, sense receptorand lot of nerves. It is also called as nerve cell.The three main parts of neuron are the cell body, dendrites and axon.
b) Ans: Nerve is a bundle of nerve fibres andthe thread like white structures which emerge from the brain and spinal cord and branch out to almost all parts of the body. We can compare nerves to an underground electric cable containing conducting wires, each insulating from the other. Myelin sheath of an axon acts like an insulation and prevent mixing of impulses in the adjacent axons.
c) Ans: A sudden change of the external or internal environment that results in a change in an organism Or an other body parts. It acts like an agent. Eg. Sound, Light, Heat, Pain, Hunger.
d) Ans: Axon terminals are closely placed near the dendrites of another one or more neurons and they are not connected such gaps are called synaptic cleft.
e) Ans: An automatic and immediate involuntary action in the body brought about by a stimulusis called reflex action.
f) Ans: corpus callosum is an sheet of fibres connecting between the two cerebral hemispheres. It transfers information from one hemisphere to another.
2) Distinguish between the following pairs.
a) Ans:
Cerebrum |
Cerebellum |
Cerebrum controls voluntary actions. The highly developed cortex of cerebrum enable us to think, plan as well as memories and that is why it is a seat of intelligence and will power. | The main function of cerebellum is to maintain body balance. It also coordinate muscular activity.
|
b) Ans:
Sympathetic nervous system |
Parasympathetic nervous system |
Location of sympathetic nerves is, it arrives from spinal cord between the neck and waist region | Parasympathetic nervous system is located at two places, one anteriorly in the head and neck and other posteriorly in sacral region. |
It’s role is to prepare the body for violent action against abnormal conditions. | This system is more concerned with re-establishing normal conditions after the violent act is over. |
c) Ans:
Sensory nerve |
Motor nerve |
The direction of impulse carried in sensory nerve is as follows,
Neuron in the spinal cord receives nerve impulse through its axon ending which in contact with receptor cell. |
Motor nerve carries impulse generated by the association neuron in the CNS to the effector organ like muscle and gland. |
d) Ans:
Cerebrum |
Spinal cord |
In the cerebrum cyton is outside and axon is inside which gives gray appearance to the brain. | In spinal cord the cyton is inside and the axon is outside and gives white appearance. |
e) Ans:
Cranial nerves |
Spinal nerves |
There are 12 pairs of cranial nerves present in the body of human. | There are 31 pairs of spinal nerves present in human body. |
f) Ans:
Nerve impulse |
Flow of electricity |
Nerve impulse travels only 100 meters per second at its maximum. | Electricity is transmitted through a wire at a speed of1,50,000km. per second. |
g) Ans:
Medulla Oblongata | Cerebellum |
The function of medulla Oblongata is to control the activities of internal organs and other involuntary actions. | The function of cerebellum is to coordinate muscular activities and to maintain balance of the living body. |
3) Ans: Effect on organs given in below table,
Organ |
Sympathetic system |
Parasympathetic system |
Eg. Lungs | Dilates bronchi and bronchioles | Constricts bronchi and bronchioles |
1.Heart | Heartbeat accelerates | Heartbeat retards |
2.Pupil of the eye | Dilates | Constricts |
3.Salivary gland | Inhibits the secretion of saliva which causes drying of the mouth. | Release of saliva stimulates. |
4.Give reason:
a) Ans- Brain is protected by the skull or cavity and neural structure travels from back of the brain, down the middle of the spine and stopping within the lumbar region of the lower back therefore the brain and spinal cord referred to as central nervous system because the central nervous system controls our thoughts, actions, emotions and desires. It also controls breathing, heart rate, body temperature and much more.
b) Ans: Neurotransmitters are the chemical substances and they are liberated from the axon terminal which helps in the forward movement of nuclear impulse. If the neurotransmitters are not broken down then the impulse from the nervous system do not end and there would be constant stimulation of the muscle. Thus they broken down by an enzyme from one neuron to the other neuron immediately after passing an impulse from one
5) Ans: Following are the advantages of having a nervous system,
- Nervous system helps body parts to communicate each other.
- Because of the nervous system we can quickly detect a stimulus and communicate with external as well as internal environment to make an appropriate response.
- It keeps us informed about the surroundings through sense organs.
- Nervous system allows to carry information generated from one part of body to other.
E) STRUCTURED/APPLICATION/SKILL TYPE
1) Ans: Salivation can be occur as a natural reflex. Saliva starts to flow downwards when you chew or eat food. But in this situation of two hungry boys, the sight and smell of food is enough for the response. Boy B’s brain actually remembered the taste of the food and worked in an unconscious wayie. he must have tasted that food previously unlike boy A and because of this boy B starts salivating.
2) Ans:
a) Ans:
Part 1- Parietal lobe of cerebral cortex.
Part 2 – Cerebellum
Part 3 –Pons
Part 4 – Modulla oblongata
b) Ans: The protective membranous covering of the brain called as meninges. It’s three layers are, dura mater, arachnoid and pia mater.
c) Ans: Basic unit of the brain is neuron.
d) Ans: Important role of part 2 i.e. cerebellum is to maintain muscular activity and balance of the body and
3) Ans :- Effective change is as shown in table below,
Situation | Organ/body part | Change /action | Part of autonomic nervous system involved |
You have entered a dark room. | Eye | Dilation of pupil | Sympathetic |
Your body is consuming lot of glucose while running a race. | Liver | In the liver, glycogen is converted into glucose | Sympathetic |
You are chewing a tasty food. | Salivary gland | Salivation increases | Parasympathetic |
You are running a race | Adrenal gland | Release of adrenaline and non-adrenaline increases | Sympathetic |
You are retiring to bed for sleep | Heart | Heart rate decreases | Parasympathetic |
You are shivering an intense cold. | Body hairs | Hair raised. | Sympathetic |
4) Ans:-
Here is your solution of Selina Concise Class 10 Biology Chapter 10 The Nervous System
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