Frank Solutions for Chapter 9 Nervous System Class 10 Biology ICSE


1. Name the following:

(i) Nervous system including brain and spinal cord.
Central Nervous System

(ii) Sympathetic and parasympathetic jointly forms.
Autonomic Nervous System

(iii) Terminal end of spinal cord.
Conus medullaris/Medullary cone

(iv) The third neuron that is involved in reflexes, other than simple reflex.
Mixed neurons

(v) Study of structure and functions of nervous system.

(vi) Nerve which carry impulse from sensory receptor to CNS.
Sensory neurons

(vii) The nerve which carry impulse from CNS to muscles.
Motor neurons

(viii) The peripheral matter of spinal nerve.
White matter

(ix) The peripheral matter of the brain.
White matter

(x) Outermost meningeal membrane of spinal cord.
Dura mater

(xi) Structural and metabolic unit of nervous tissue.

(xii) The biological term given to the protective membranes of the brain.

(xiii) Cavity in which brain is situated.

(xiv) The neobrain.

(xv) The important center of emotion.
Limbic system

(xvi) Paired lobes of midbrain related to the vision.
Corpora quadrigemina

(xvii) Paired lobes of the brain related to the sense of smell.
Olfactory Lobes

(xviii) Fissure between the cerebral hemispheres.
Median fissure

(xix) Inability to write.

(xx) The busiest organ of the body.

(xxi) Inability to speak.

(xxii) The longest cranial nerve.
Trigeminal nerve

(xxiii) Thoracolumbar region of spinal cord form.
Sympathetic nervous system

(xxiv) Highly branched axon's end.

(xxv) Neuron only with axon.
Bipolar neuron

(xxvi) White part of the eye.

(xxvii) Short sightedness.

(xxviii) Part of internal ear related to balance.
Semicircular canal

(xxix) The photosensitive pigment present in the rod cells of the retina.

2. Define 
(i) Ear pinna
(ii) External auditory meatus
(iii) Cochlea
(iv) Semicircular canals
(v) Lachrymal gland
(vi) Eyelids
(vii) Retina 
(viii) Eye lens
(ix) Pupil
(x) Olfactory lobe
(xi) optic lobe 
(xii) Medulla oblongata
(i) Ear pinna: The pinna or the external ear collects the sound waves from different directions and send them to the middle ear.

(ii) External auditory meatus: It forms a passage from the pinna to the eardrum.

(iii) Cochlea: It converts vibrations into nerve impulses and thus helps in hearing.

(iv) Semicircular canals: It responds to change in position and maintains balance.

(v) Lachrymal gland: It secretes a watery fluid which washes the surface of eyes.

(vi) Eyelids: It blinks to clean the dust and grit from the cornea.

(vii) Retina: It is a photosensitive layer to receive the image.

(viii) Eye lens: It focuses the image on the retina.

(ix) Pupil: It regulates the amount of light that enters the eye.

(x) Olfactory lobe: These are concerned with the sense of smell.

(xi) Optic lobe: These are concerned with vision.

(xii) Medulla oblongata: It controls involuntary functions of the body like – coughing, swallowing, breathing, heartbeat, etc.

3. Select the odd one in the following series:
(i) Retina, Sclera, Ciliary body, Nephron.
(ii) Endolymph, Tympanic membrane, Semi-circular canal, Blind spot.
(iii) Prosencephalon, Mesencephalon, Rhombencephalon, Myelin.
(iv) Cerebellum, Medulla oblongata, Olfactory lobe.
(v) Parasympathetic, Sympathetic, Cranial nerve.

(i) Nephron
(ii) Blind spot
(iii) Myelin
(iv) Olfactory lobe
(v) Cranial nerve

4. Match the terms of column I with those of column II
Column I Column II
(i) Lens (a) Adjustment of light rays
(ii) Lachrymal gland (b) Vision
(iii) Olfactory epithelium (c) Secretion of tear
(iv) Cochlea  (d) Balance of the body
(v) Semicircular canal (e) Hearing
(vi) Eyes (f) Smell
Column I Column II
(i) Lens (a) Adjustment of light rays
(ii) Lachrymal gland (c) Secretion of tear
(iii) Olfactory epithelium (f) Smell
(iv) Cochlea  (e) Hearing
(v) Semicircular canal (d) Balance of the body
(vi) Eyes (b) Vision

5. Define the following:

(i) Nerve impulse
(ii) Axon
(iii) Cyton
(iv) Action potential
(v) Reflex action
(vi) Yellow spot
(vii) Blind spot
(viii) Power of accommodation

(i) Nerve impulse - It is an electrochemical change occurring in the membrane of a nerve fibre produced by a stimulus.

(ii) Axon - It is a fibre like process of the neuron which carries impulses away from the cell body.

(iii) Cyton - It is an oval, angular, polygonal or stellate body which contains a large central nucleus.

(iv) Action potential - A momentary change in electrical potential on the surface of a cell, or a nerve or muscle cell, that occurs when it is stimulated, resulting in the transmission of an electrical impulse.

(v) Reflex action - It is an immediate and involuntary response to a stimulus.

(vi) Yellow spot - It is the region of best vision where more cone cells are present.

(vii) Blind spot - It is the region of no image formation because of lack of cone cells.

(viii) Power of accommodation – It is the ability of the lens to focus on far and distant objects.

6. Distinguish between the following pairs of words:
(i) Nerve cell and neuroglia cell
(ii) Nervous system and hormonal system
(iii) Cranial nerve and spinal nerve
(iv) Cerebrum and cerebellum
(v) Adrenalin and acetylcholine
(vi) Motor and sensory nerve
(vii) Grey matter and white matter
(viii) Myopia and hypermetropia
(i) Difference between Nerve cell and neuroglia cell
Nerve cell Neuroglia cell
These are the conducting cells in the nervous system which conduct impulses.  These are not the conducting cells but are helper cells to the nerve cells or neurons.

(ii) Difference between Nervous system and hormonal system
Nervous system Hormonal system
(i) It co-ordinates the body through electrical impulses. (i) It secretes hormones.
(ii) The nervous system controls muscles movement, senses, heartbeat, breathing, digestion, memory and speech (ii) The endocrine system controls levels of glucose in the blood, hydration levels, heat productivity, sexual maturity, sperm and egg production and growth of cells and tissues.

(iii) Difference between Cranial nerve and Spinal nerve
Cranial nerve Spinal nerve
(i) They arise from brain. (i) They arise from spinal cord
(ii) There are 12 pairs of cranial nerves. (ii) There are 31 pairs of spinal nerves.

(iv) Difference between Cerebrum and Cerebellum
Cerebrum Cerebellum
It is concerned with intelligence, memory and voluntary activities.  It is concerned with body equilibrium

(v) Difference between Adrenalin and acetylcholine
Adrenalin  Acetylcholine
It is a neurotransmitter which increases the heart beat to meet any emergency It is a neurotransmitter which slows down the heart beat.
(vi) Difference between Motor and sensory nerve
Motor nerve  Sensory nerve
A motor nerve contains motor fibres which bring impulses from the brain or spinal cord to the effector organs. A sensory nerve contains sensory fibres which bring impulses from the sense organs to the brain or spinal cord.
(vii) Difference between Grey matter and white matter
Grey matter White matter
(i) It is composed of cell bodies of a nerve cell. (i) It is composed of axons from the nerve cells.
(ii) It lies outside the brain but inside the spinal cord. (ii) It lies inside the brain but outside the spinal cord.
(viii) Difference between Myopia and Hypermetropia
Myopia Hypermetropia
(i) The image of distant object is produced in the front and not on the retina. (i) The image is produced beyond the retina as the light rays are unable to coverge on the retina.
(ii) It results from abnormally long eyeball.  (ii) It results from abnormally short eyeball.
(iii) The defect can be produced by high convexity of the lens. (iii) The defect can be produced by low convexity of the lens.
(iv) It can be corrected by the use of spectacles having concave lens. (iv) It can be corrected by the use of spectacles having convex lens.

7. Label the following diagrams
(a) Vertical section of Human eye

(b) Longitudinal section of Human brain

8. (i) Draw a well-labelled diagram of the vertical section of mammalian brain.
(ii) Which part of the brain is the seat of body temperature regulation?
(iii) Name the part of the brain responsible for sense of smell and mental function of intelligence and memory.
(i) Vertical section of Mammalian brain.
(ii) Diencephalon
(iii) Cerebrum

9. Draw a diagram of the side view of human brain and label the part which suits the following functions/descriptions:
(i) It lies below and behind the cerebrum. It consists of three parts.
(ii) It is a cross-wise broad band of fibres which comments medulla oblongata, cerebellum and cerebrum.
(iii) It is the lower most and hinder part of the brain which continues below into spinal cord
(iv) It is a small thick-walled area which lies hidden below the cerebrum.
(v) It is the largest part of the brain which constitutes more than 80% and possesses 6-7 billion neurons.
(vi) It takes part in relaying sensory impulses and regulation of smooth muscle activity?
(i) Cerebellum 
(ii) Cerebral peduncles
(iii) Medulla oblongata
(iv) Olfactory lobes
(v) Cerebrum
(vi) Diencephalon

10. Briefly explain about Cerebrum, Cerebellum, Medulla oblongata 
A – Cerebrum; B – Cerebellum; C – Medulla oblongata
(a) Cerebrum – It is concerned with intelligence, memory and voluntary activities.
(b) Cerebellum – It is concerned with body equilibrium.
(c) Medulla oblongata It controls all involuntary activities like heart beat, respiration, etc.
The three protective membranes covering the brain are :
  • Dura mater
  • Arachnoid mater
  • Pia mater.
• Neuron is the basic unit of the brain.

11. Where are these located?
(i) Meninges
(ii) Ganglia
(iii) Cerebellum
(iv) Nodes of Ranvier
(v) Effector organs
(i) Meninges - It is located around the brain and spinal cord.
(ii) Ganglia - It is located outside the brain and spinal cord.
(iii) Cerebellum - It is located behind cerebrum and above medulla oblongata in the brain.
(iv) Nodes of Ranvier - It is located on the unmyelinated areas on the axon.
(v) Effector organs - It is located in muscle , gland or any organ of the body.

12. Draw a labelled diagram of the front view the human eye.
Human eye

13. Differentiate between nerve and neuron
Difference between Nerve and Neuron
Nerve  Neuron
It is a collection of axons leading to or from the central nervous system. A nerve cell with its processes is called a neuron

14. Name the respective organs in which the following are located and mention the main function of each:
(i) Iris
(ii) Semicircular canals
(i) Iris: It is located in the eye. Its function is to protect the eyeball and controls the size of the pupil.
(ii) Semicircular canals: It is located in the inner ear. These are concerned with the body equilibrium.

15. Give two examples of reflex actions in our daily life.
Following are the two examples of reflex actions in our daily life :
(i) Removing hand suddenly when pricked by a thorn.
(ii) Blinking of eyelids on exposure to light.

16. (i) What is a reflex action?
(ii) Give one example of a conditioned reflex in your own life.
(i) Reflex action - It is an immediate and involuntary response to a stimulus.
(ii) Example of a conditioned reflex: Tying one’s shoe lace.

17. The diagram alongside represents the structure of the human ear.
(i) Write the names of the parts labelled a to g.
(ii) State briefly the functions of the parts b, d, and g.
(iii) Name the main division of the ear.
(iv) Which is the smallest bone in the human body?
(v) What is labyrinth?
(i) (a) Bone of skull
(b) Inner ear
(c) Eardrum
(d) Bone of skull
(e) Bone of middle ear
(f) Middle ear
(g) Air filled

(ii) (b) Inner ear - It transmits the impulse to brain.
(d) Bone of skull - It helps in fixing the position of the ears to help the brain use auditory cues to judge direction and distance of sounds.
(g) Air filled – It keeps the pressure in the middle ear equalized with pressure in the outside.

(iii) The main division of the ear are: outer ear, middle ear and inner ear.
(iv) Stirrup
(v) The labyrinth is the inner ear which consists of utriculus, sacculus, cochlea and three semicircular canals.

18. The diagram alongside represents the structure found in the inner ear. Study the same and then answer the questions that follow:
(i) Name the parts labelled A, B, C and D.
(ii) Name the parts of the ear responsible for transmitting impulses to the brain.
(iii) Name the part labelled above which is responsible for:
1. Static equilibrium. 2. Dynamic equilibrium. 3. Hearing
(iv) Name the audio receptor cells which pick up vibrations.
(v) Name the fluid present in the inner ear.

(i) A - Semi-circular canal
B - Utriculus
C - Sacculus
D - Cochlea
(ii) Auditory nerve.
(iii) 1. Utriculus and sacculus
2. Semi-circular canal
3. Cochlea
(iv) Sensory cells of organ of Corti
(v) Perilymph

19. Give the main functions of each of the following:
(i) Cochlea
(ii) Fovea centralis
(iii) Three semicircular canals
(iv) Retina
(v) Lachrymal glands
(i) Cochlea - It helps in hearing by transmitting impulses to the brain through auditory nerves.
(ii) Fovea centralis - It is a point at retina where more cone cells are concentrated and thus produces sharpest vision.
(iii) Three semicircular canals - It maintains the dynamic equilibrium.
(iv) Retina- It prevents the reflection of light.
(v) Lachrymal glands - It produces tear to lubricate the eyeball.

20. Give one point of difference between the following on the basis of what is indicated:
Cerebrum and spinal cord. (Arrangement of neurons)
The arrangement of neurons in
  • Cerebrum: cytons are present outside and axons are inside
  • Spinal cord: cytons are present inside and axons are outside.

21. Describe briefly the functions of medulla oblongata.
Functions of medulla oblongata:
  • It controls the involuntary activities like - respiration, circulation, digestion, etc.
  • It controls the dilation and constriction of blood vessels.

22. What is meant by 'reflex action'? Mention any two examples of reflex action occurring in day-to-day life.
Reflex action: It is an immediate and involuntary response to a stimulus.
Example: 1. Blinking of eyelids on exposure to light .
2. Knee jerk.

23. The diagram alongside represents a certain defect of vision of the human eye.
(i) Name the defect.
(ii) Describe briefly the condition in the eye responsible for the defect.
(iii) Redraw the figure by adding a suitable lens correcting the defect. Label the parts through which light-rays pass.
(iv) What special advantage do human beings derive in having both eyes facing forward?

(i) Hypermetropia
(ii) There are two main conditions in the eye which is responsible for this defect:
  • Shortening of the eyeball from front to back.
  • The lens is less concave.
(iii) Correction of hypermetropia:
(iv) Both the eyes facing forward helps in judging the depth or relative distance. this is due to overlapping images formed in brain from both eyes which focus on an object together at one time.

24. Name the cells of the retina that are sensitive to colors.
Cone cells.

25. The diagram alongside represents a section of a mammalian eye.
(i) Label the parts 1 to 5 of the diagram.
(ii) State the function of the parts labelled 4 and 5.
(iii) With the help of a diagram show the short sightedness.

(i) 1 - Retina
2 - Yellow
3 - Blind spot
4 - Optic nerve
5 - lens
(ii) Optic nerve - It transmits the impulses to the brain.
Lens - It focuses the image on the retina
(iii) Short sightedness:

26. Given alongside is a diagram depicting a defect of the human eye. study the same and then answer the questions that follow:
(i) Identify the defect
(ii) Name the parts labelled 1,2 and 3.
(iii) Give labelled two possible reasons for this eye defect.
(iv) Draw a labelled diagram to show how the above mentioned defect is rectified.
(i) Myopia
(ii) 1. Vitreous humor
2. Fovea
3. Optic nerve
(iii) 1. Lengthening of the eyeball from front to back.
2. Lens is too curved.
(iv) Correction of myopia: 

27. Fill in the blanks with the function in the following:
Cochlea: ______
Meninges: ______
(i) Cochlea: It helps in hearing by transmitting impulses to the brain through auditory nerves.
(ii) Meninges: It provides protection to brain and spinal cord.

28. Why does one feel blinded for a short while on coming out of a dark room?
One feels blinded for a short while on coming out of a dark room. This is called light adaptation of the eye. It is due to the constriction of the pupil to prevent the entry of light into the eye and pigment rhodopsin is bleached to reduce the sensitivity of the rods.

29. Name the following:
(i) The opening through which light enters the eyes.
(ii) The fluid that is present inside and outside the brain.
(i) Iris
(ii) Cerebrospinal fluid

30. Write whether the following are true or false:

(i) Axon of one neuron communicates with other nerve cell through synapse.

(ii) Neurotransmitters are released on activation.

(iii) Neurotransmitters are either broken down or reabsorbed after they have conducted an impulse.

(iv) All voluntary actions are controlled by the cerebellum.

(v) A convex lens is used for correcting myopia.

(vi) Rods are the receptor cells in the retina of the eye sensitive to dim light.

(vii) The part of the ear associated with balance is the cochlea.

(viii) Vitreous chamber is present in ear in humans.

31. Choose the correct answer.

(i) More than one foot long cells of the body are
(a) gland cell 
(b) RBC 
(c) bone cell 
(d) nerve cell
(d) nerve cell

(ii) The largest part of the brain
(a) medulla 
(b) cerebrum 
(c) fornix 
(d) optic lobe
(b) cerebrum 

(iii) Number of spinal nerves in human beings
(a) 31 
(b) 10 
(c) 21 
(d) 12
(a) 31 

(iv) Number of cranial nerves
(a) 10 
(b) 12 
(c) 14 
(d) 20
(b) 12 

(v) Outermost covering of the brain is
(a) dura mater 
(b) pia mater 
(c) arachnoid 
(d) pericardium
(a) dura mater 

(vi) Labyrinth is a part of
(a) ear 
(b) brain 
(c) nose 
(d) eye
(a) ear 

(vii) In the chemistry of vision, the photosensitive substance is
(a) melanin 
(b) sclerotin 
(c) rhodopsin 
(d) none
(c) rhodopsin 

(viii) Rods are receptor of
(a) twilight vision 
(b) colour vision 
(c) sound wave 
(d) odour
(a) twilight vision 

(ix) Which one is the photoreceptor
(a) organ of corti
(b) organ of sylvious
(c) cristae
(d) macula
(d) macula

(x) Synapse is a close proximity of
(a) two veins
(b) two arteries
(c) two muscles
(d) two nerves
(d) two nerves

(xi) Auditory nerve is responsible for
(a) smell 
(b) sight 
(c) hearing 
(d) none
(c) hearing 

(xii) Man has ______ pairs of spinal nerves.
(a) 30 
(b) 31 
(c) 32 
(d) 40
(b) 31 

(xiii) Canal joining middle ear to pharynx
(a) eustachian
(b) tympanic
(c) labyrinth
(d) none
(a) eustachian

(xiv) Aperture controlling passage to light into the eye is
(a) blind spot
(b) pupil
(c) iris
(d) cornea
(c) iris

(xv) Colour is detected by
(a) rods 
(b) cones 
(c) pigment 
(d) choroids
(b) cones 

(xvi) Organ of corti is found in
(a) eye 
(b) Ear 
(c) skin 
(d) none
(b) Ear 

(xvii) The cerebral hemispheres in mammals are connected by
(a) corpus luteum
(b) hypothalamus
(c) pons varolli
(d) corpus callosum
(d) corpus callosum

(xviii)Presbyopia is a disease of
(a) ear 
(b) nose 
(c) mouth 
(d) eye
(d) eye

(xix) The rods and cones of a vertebrate retina function is to
(a) focus light
(b) amplify light
(c) transduce light
(d) filter light
(d) filter light

(xx) In mammals the corpus callosum connects
(a) the two optic lobes
(b) the two cerebral hemispheres
(c) the cerebrum to the cerebellum
(d) the pons to the medulla oblongata
(b) the two cerebral hemispheres
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