Frank Brothers Solutions for ICSE Class 10 Biology Chapter 9 Nervous System

Page No 115

Solution 1.
Answer:
1. Central Nervous System
2. Autonomic Nervous System
3. Conus medullaris / Medullary cone
4. Mixed neurons
5. Neuroscience
6. Sensory neurons
7. Motor neurons
8. White matter
9. White matter
10. Dura mater
11. Neuron
12. Meninges
13. Cranium
14. Neocortex / Neopallium
15. Limbic system
16. Corpora quadrigemina
17. Olfactory Lobes
18. Median fissure
19. Agraphia
20. Brain
21. Aphasia
22. Trigeminal nerve
23. Sympathetic nervous system
24. Dendrites
25. Bipolar neuron
26. Sclera
27. Myopia
28. Semicircular canal
29. Rhodopsin
In simple words: These are the correct scientific terms for different parts and functions of the nervous system, from brain structures to nerve types to eye defects.

📝 Teacher's Note: Have students create a word bank with these terms and their definitions. Visual aids and models help students connect terms to actual body parts they can see or touch.

🎯 Exam Tip: Memorize the spelling of technical terms like "Corpora quadrigemina" and "Neopallium" as these are commonly misspelled in exams.

Page No : 116

Solution 2.
Answer:
1. Ear pinna – The pinna or the external ear collects the sound waves from different directions and send them to the middle ear.
2. External auditory meatus – It forms a passage from the pinna to the eardrum.
3. Cochlea – It converts vibrations into nerve impulses and thus helps in hearing.
4. Semicircular canals – It responds to change in position and maintains balance.
5. Lachrymal gland – It secretes a watery fluid which washes the surface of eyes.
6. Eyelids – It blinks to clean the dust and grit from the cornea.
7. Retina – It is a photosensitive layer to receive the image.
8. Eye lens – It focuses the image on the retina.
9. Pupil – It regulates the amount of light that enters the eye.
10. Olfactory lobe – These are concerned with the sense of smell.
11. Optic lobe – These are concerned with vision.
12. Medulla oblongata – It controls involuntary functions of the body like – coughing, swallowing, breathing, heartbeat, etc.
In simple words: Each part of our sensory organs has a specific job - ears collect and process sound, eyes capture and focus light, and brain parts control our senses and automatic body functions.

📝 Teacher's Note: Use real examples like cupping ears to hear better or watching pupils dilate in dim light. Students learn better when they can connect to their own experiences.

🎯 Exam Tip: Remember the function follows the structure - curved ear pinna collects sound, flexible lens focuses light, etc. This logical connection helps recall.

Solution 3.
Answer:
1. Nephron
2. Blind spot
3. Myelin
4. Olfactory lobe
5. Cranial nerve
In simple words: These are specific technical terms for kidney filtering units, eye's non-seeing area, nerve covering, smell center, and head nerves respectively.

📝 Teacher's Note: This appears to be a fill-in-the-blanks exercise. Provide students with the context or sentences where these terms would fit to make learning more meaningful.

🎯 Exam Tip: If this is a matching or fill-in exercise, read all options first before answering to avoid using a term in the wrong place.

Solution 4.
Answer:
(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
In simple words: This matches body parts with their main jobs - lens bends light, tear glands make tears, nose detects smells, ear parts help hearing and balance, eyes see.

📝 Teacher's Note: Create a matching game with cards. Students enjoy hands-on activities that reinforce the structure-function relationship in sensory organs.

🎯 Exam Tip: In matching questions, eliminate obvious pairs first, then work through the remaining options systematically.

Solution 5.
Answer:
1. Nerve impulse – It is an electrochemical change occurring in the membrane of a nerve fibre produced by a stimulus.
2. Axon – It is a fibre like process of the neuron which carries impulses away from the cell body.
3. Cyton – It is an oval, angular, polygonal or stellate body which contains a large central nucleus.
4. 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.
5. Reflex action – It is an immediate and involuntary response to a stimulus.
6. Yellow spot – It is the region of best vision where more cone cells are present.
7. Blind spot – It is the region of no image formation because of lack of cone cells.
8. Power of accommodation – It is the ability of the lens to focus on far and distant objects.
In simple words: These definitions explain how nerves send electrical messages, what different nerve parts do, and how our eyes work to see clearly at different distances.

📝 Teacher's Note: Use analogies - nerve impulse like electricity through wires, axon like telephone cable, reflex like automatic door. Make abstract concepts concrete.

🎯 Exam Tip: Learn key phrases like "electrochemical change," "involuntary response," and "electrical potential" as these exact terms score full marks in definitions.

Solution 6.
Answer:
(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 –

In simple words: These comparisons show the differences between related parts of the nervous system - like helpers vs workers, fast electrical vs slow chemical communication, brain vs spinal nerves, thinking vs balance parts, and opposite eye problems.

📝 Teacher's Note: Use a comparison chart on the board. Students understand better when they can see both similarities and differences side by side. Act out reflexes vs voluntary actions.

🎯 Exam Tip: In comparison questions, always give at least 2-3 points of difference. Mention location, function, and structure where relevant for full marks.

Solution 7.
Answer:
(a) Vertical section of Human eye:
[Diagram showing labeled parts: Vitreous Humour, Suspensory ligament, Aqueous Humour, Conjunctiva, Cornea, Pupil, Lens, Iris, Ciliary Muscles, Sclera, Extrinsic Muscles, Optic nerves, Blind spot, Yellow spot, Retina, Choroid]

(b) Longitudinal section of Human brain:
[Diagram showing labeled parts: Cerebrum, Corpus callosum front, Optic lobe, Ventricle containing cerebrospinal fluid, Thalamus, Cerebellum, Hypothalamus, Pituitary, Pons, Spinal Cord, Medulla]
In simple words: These diagrams show the inner structure of the eye (how we see) and brain (how we think and control our body) with all important parts labeled.

📝 Teacher's Note: Use 3D models if available. Have students trace the path of light through the eye and nerve signals through the brain. Kinesthetic learning enhances retention.

🎯 Exam Tip: Practice drawing and labeling these diagrams multiple times. Examiners award marks for neat, accurate labeling with proper lines pointing to structures.

Page No : 117

Solution 8.
Answer:
[Diagram of brain showing sagittal section with labeled parts]
(i) Cerebellum
(ii) Cerebral peduncles
(iii) Medulla oblongata
(iv) Olfactory lobes
(v) Cerebrum
(vi) Diencephalon
In simple words: This brain diagram shows the major sections including the thinking part (cerebrum), balance part (cerebellum), breathing control (medulla), and smell center (olfactory lobes).

📝 Teacher's Note: Connect each brain part to its function with real examples - cerebellum for riding a bike, medulla for automatic breathing, cerebrum for solving math problems.

🎯 Exam Tip: Learn the exact spelling of "Diencephalon" and "Cerebellum" - these are frequently misspelled and cost marks in labeling questions.

Solution 9.
Answer:
[Diagram of brain showing sagittal section with labeled parts]
(i) Cerebellum
(ii) Cerebral peduncles
(iii) Medulla oblongata
(iv) Olfactory lobes
(v) Cerebrum
(vi) Diencephalon
In simple words: This is the same brain labeling as Solution 8, showing the major control centers of our nervous system.

📝 Teacher's Note: This appears to be a duplicate of Solution 8. Use this as an opportunity to reinforce learning through repetition and ensure students have mastered the brain anatomy.

🎯 Exam Tip: If you see similar diagrams in exams, double-check that you're labeling the correct structures as indicated by the question numbers or arrows.

Solution 10:

• A – Cerebrum; B – Cerebellum; C – Medulla oblongata
• (A) Cerebrum – It is concerned with intelligence, memory and voluntary activities.
• Cerebellum – It is concerned with body equilibrium.
• 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

5. Neuron is the basic unit of the brain.

📝 Teacher's Note: Use a simple brain model or diagram to show students the three main parts and their locations. Ask students to relate each part's function to everyday activities they can understand.

🎯 Exam Tip: Remember the mnemonic "DAP" for the three protective membranes: Dura, Arachnoid, Pia. Always mention all three functions of the brain parts for full marks.

Solution 11:

1. Meninges – It is located around the brain and spinal cord.
2. Ganglia – It is located outside the brain and spinal cord.
3. Cerebellum – It is located behind cerebrum and above medulla oblongata in the brain.
4. Nodes of Ranvier – It is located on the unmyelinated areas on the axon.
5. Effector organs – It is located in muscle, gland or any organ of the body.

📝 Teacher's Note: Help students visualize these locations using anatomical models. Emphasize the relative positions of brain parts using directional terms like "behind," "above," and "around."

🎯 Exam Tip: Be precise with anatomical locations. Use proper directional terminology and always specify the complete location for each structure.

Solution 12:

Human eye: [Diagram shows labeled parts including Lachrymal gland, Tear ducts, Eyelashes, Upper eyelid, Canals (ducts), Iris, Sclera, Lower eyelid, Nasal duct, Pupil, and Nasal cavity]

📝 Teacher's Note: Use this diagram to explain the protective structures of the eye. Point out how tear ducts and lachrymal glands work together to keep the eye moist and clean.

🎯 Exam Tip: When labeling eye diagrams, ensure you can identify both external protective structures and internal parts. Practice drawing the tear duct system pathway.

Solution 13:

Difference between nerve and neuron:

📝 Teacher's Note: Use the analogy of a nerve being like a cable with many wires (neurons) inside. This helps students understand the structural difference between individual cells and bundles.

🎯 Exam Tip: Remember that a nerve is a bundle of many neurons, while a neuron is a single cell. Always mention "collection" or "bundle" when describing nerves.

Solution 14:

1. Iris: It is located in the eye. Its function is to protect the eyeball and controls the size of the pupil.
2. Semicircular canals: It is located in the inner ear. These are concerned with the body equilibrium.

📝 Teacher's Note: Demonstrate pupil dilation/constriction using a flashlight. Explain how semicircular canals work like a spirit level in a toolbox to detect movement and balance.

🎯 Exam Tip: For iris, mention both protection and pupil size control functions. For semicircular canals, always connect them to balance and equilibrium.

Solution 15:

Following are the two examples of reflex actions in our daily life:

1. Removing hand suddenly when pricked by a thorn.
2. Blinking of eyelids on exposure to light.

📝 Teacher's Note: Demonstrate these reflexes safely in class. Explain that reflexes happen automatically without thinking – they protect us from harm faster than conscious thought.

🎯 Exam Tip: Always give examples that show the protective nature of reflexes. Use action verbs like "removing," "blinking," "jerking" to show the immediate response.

Solution 16:

1. Reflex action – It is an immediate and involuntary response to a stimulus.
2. Example of a conditioned reflex: Tying one's shoe lace.

📝 Teacher's Note: Distinguish between natural reflexes (like blinking) and learned reflexes (like tying shoelaces). Students often confuse these two types.

🎯 Exam Tip: Define reflex action using both key terms: "immediate" and "involuntary." For conditioned reflexes, choose learned behaviors that become automatic.

Solution 17:

1. (a) Bone of skull
2. (b) Inner ear
3. (c) Eardrum
4. (d) Bone of skull
5. (e) Bone of middle ear
6. (f) Middle ear
7. (g) Air filled
8. (ii) (b) Inner ear – It transmits the impulse to brain.
9. (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.
10. (g) Air filled – It keeps the pressure in the middle ear equalized with pressure in the outside.
11. (iii) The main division of the ear are: outer ear, middle ear and inner ear.
12. (iv) Stirrup
13. (v) The labyrinth is the inner ear which consists of utriculus, sacculus, cochlea and three semicircular canals.

📝 Teacher's Note: Use ear models to show the three divisions clearly. Explain pressure equalization by having students yawn or swallow to feel their ears "pop."

🎯 Exam Tip: Remember the three ear divisions in order: outer, middle, inner. For labyrinth components, use the mnemonic "USCS" - Utriculus, Sacculus, Cochlea, Semicircular canals.

Solution 18:

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

📝 Teacher's Note: Connect each inner ear structure to its function: semicircular canals for dynamic balance, utriculus/sacculus for static balance, cochlea for hearing.

🎯 Exam Tip: When labeling inner ear diagrams, start with the largest structure (cochlea) and work inward. Always mention the auditory nerve as the connection to the brain.

Solution 19:

1. Cochlea – It helps in hearing by transmitting impulses to the brain through auditory nerves.
2. Fovea centralis – It is a point at retina where more cone cells are concentrated and thus produces sharpest vision.
3. Three semicircular canals – It maintains the dynamic equilibrium.
4. Retina – It prevents the reflection of light.
5. Lachrymal glands – It produces tear to lubricate the eyeball.

📝 Teacher's Note: Explain fovea centralis as the "sweet spot" of vision where we see things most clearly. Demonstrate by having students focus on text while moving their eyes.

🎯 Exam Tip: For cochlea, always mention both hearing and auditory nerve transmission. For fovea, emphasize "cone cells" and "sharpest vision" for full marks.

Solution 20:

The arrangement of neurons in
Cerebrum: cytons are present outside and axons are inside
Spinal cord: cytons are present inside and axons are outside.

📝 Teacher's Note: Use the analogy of electrical wiring: in cerebrum, the "control centers" (cytons) are on the outside like switches, while in spinal cord, they're protected inside like a fuse box.

🎯 Exam Tip: Remember the arrangement is opposite in cerebrum vs spinal cord. Use the contrast "outside-inside" vs "inside-outside" to avoid confusion.

Solution 21:

Functions of medulla oblongata –

1. It controls the involuntary activities like – respiration, circulation, digestion, etc.
2. It controls the dilation and constriction of blood vessels.

📝 Teacher's Note: Emphasize that medulla oblongata controls "life-sustaining" functions that happen automatically. Students can relate this to breathing during sleep.

🎯 Exam Tip: Always mention "involuntary activities" and give at least three examples: respiration, circulation, digestion. Include blood vessel control for complete answer.

Solution 22:

Reflex action – It is an immediate and involuntary response to a stimulus.
Example – 1. Blinking of eyelids on exposure to light.
2. Knee jerk.

📝 Teacher's Note: Test the knee jerk reflex safely in class if possible. Explain that reflexes bypass the brain for speed, going directly through the spinal cord.

🎯 Exam Tip: Definition must include both "immediate" and "involuntary." Choose examples that clearly show these characteristics and protective function.

Solution 23:

1. (i) Hypermetropia.
2. (ii) There are two main conditions in the eye which is responsible for this defect:
   1. Shortening of the eyeball from front to back.
   2. The lens is less concave.
3. (iii) Correction of Hypermetropia: [Diagram showing convex lens correction]
4. (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.

📝 Teacher's Note: Use simple analogies: hypermetropia is like a camera that can't focus on close objects. Explain binocular vision using two fingers at different distances.

🎯 Exam Tip: For hypermetropia, mention both causes: shortened eyeball AND less concave lens. For correction, specify convex lens is used.

Solution 24:

Cone cells.

📝 Teacher's Note: Explain that cone cells work best in bright light and are responsible for color vision, while rod cells work in dim light for black and white vision.

🎯 Exam Tip: Remember cone cells for color and bright light vision, rod cells for twilight and black-white vision. Keep the answer simple and direct.

Solution 25:

1. (i) 1 – Retina
   2 – Yellow spot
   3 – Blind spot
   4 – Optic nerve
   5 – Lens
2. (ii) Optic nerves – It transmits the impulses to the brain.
   Lens - It focuses the image on the retina.
3. (iii) Short sightedness: [Diagram showing image focus in front of retina]

📝 Teacher's Note: Use the eye diagram to explain how light travels through each part. Show students how the lens changes shape to focus on objects at different distances.

🎯 Exam Tip: For eye labeling, start with the largest structures first. Always connect structure to function in your explanations.

Solution 26:

1. (i) Myopia.
2. (ii) 1. Vitreous humor
   2. Fovea
   3. Optic nerve
3. (iii) 1. Lengthening of the eyeball from front to back.
   2. Lens is too curved.
4. (iv) Correction of Myopia: [Diagram showing concave lens correction]

📝 Teacher's Note: Contrast myopia with hypermetropia: myopia is like a camera focused too close, hypermetropia is focused too far. Use different lens shapes to demonstrate correction.

🎯 Exam Tip: For myopia, mention both causes: lengthened eyeball AND too curved lens. For correction, specify concave lens is used - opposite of hypermetropia.

Solution 27:

1. Cochlea: It helps in hearing by transmitting impulses to the brain through auditory nerves.
2. Meninges: It provides protection to brain and spinal cord.

📝 Teacher's Note: Emphasize the protective function of meninges - like a cushioned helmet for the brain. For cochlea, relate it to how a microphone picks up sound and sends signals.

🎯 Exam Tip: For cochlea, always mention both hearing and auditory nerve transmission. For meninges, specify protection of both brain AND spinal cord.

Solution 28:

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.

📝 Teacher's Note: Have students experience this by covering one eye for a minute, then uncovering it in bright light. Explain rhodopsin as the "night vision chemical" that gets overwhelmed by bright light.

🎯 Exam Tip: Mention three key points: light adaptation, pupil constriction, and rhodopsin bleaching. This shows complete understanding of the process.

Solution 29:

1. Iris
2. Cerebrospinal fluid

📝 Teacher's Note: Explain that iris controls light entry like the aperture of a camera, and cerebrospinal fluid acts like a shock absorber for the brain and spinal cord.

🎯 Exam Tip: Keep answers concise and precise. These are likely fill-in-the-blank questions requiring specific anatomical terms.

Solution 30:

1. True
2. True
3. True
4. True
5. False
6. True
7. False
8. False

📝 Teacher's Note: For True/False questions, have students explain why each false statement is incorrect. This reinforces correct understanding of the concepts.

🎯 Exam Tip: Read each statement carefully - watch for absolute terms like "always" or "never" which often make statements false. Double-check your reasoning.

Solution 31:

1. (d) nerve cell
2. (b) cerebrum
3. (a) 31
4. (b) 12
5. (a) dura mater
6. (a) ear
7. (c) rhodopsin
8. (a) twilight vision
9. (d) macula
10. (d) two nerves
11. (c) hearing
12. (b) 31
13. (a) eustachian
14. (c) iris
15. (b) cones
16. (b) Ear
17. (d) corpus callosum
18. (d) eye
19. (d) filter light
20. (b) the two cerebral hemispheres

📝 Teacher's Note: Review the commonly confused numbers: 31 spinal nerves, 12 cranial nerves. Use memory aids like "31 days in some months" for spinal nerves.

🎯 Exam Tip: For MCQs with numbers, memorize key figures: 31 spinal nerves, 12 cranial nerves. Eliminate obviously wrong options first, then choose between remaining logical choices.