Selina Concise Solutions for ICSE Class 10 Biology Chapter 8 The Nervous System

Exercise 1

Multiple Choice Type

(Select the most appropriate option in each case).

Question 1. The insulating sheath covering the neural axon is called.
(a) plasmalemma
(b) neurolemma
(c) dura mater
(d) pia mater
Answer: (b) neurolemma
In simple words: The neurolemma is like a protective plastic covering around electrical wires that prevents signals from mixing up between different nerve fibers.

📝 Teacher's Note: Use the analogy of electrical wire insulation to help students understand how neurolemma prevents nerve impulses from interfering with each other. Show students diagrams comparing myelinated and unmyelinated neurons.

🎯 Exam Tip: Remember that neurolemma is specifically for axons, while other options are brain coverings. Focus on the word "axon" in the question.

Question 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 activites of internal organs
(d) Pons - Consciousness
Answer: (d) Pons - Consciousness
In simple words: Pons acts like a bridge connecting different brain parts and helps with sleep, not consciousness which is mainly controlled by the cerebrum.

📝 Teacher's Note: Emphasize that pons means "bridge" in Latin and its main function is relaying signals between brain regions. Create a simple brain map showing each part's primary function.

🎯 Exam Tip: Look for the "not correctly matched" in the question stem. Pons is involved in sleep regulation and breathing, not consciousness.

Question 3. A mixed nerve is one which
(a) carries sensations from 2 or more different sense organs
(b) contains both sensory and motor fibres
(c) has a common root but braches into two or more nerves to different organs
(d) has two or more roots from different parts of brain.
Answer: (b) Contains both sensory and motor fibres
In simple words: A mixed nerve is like a two-way road that can carry messages both to the brain (sensory) and from the brain (motor) at the same time.

📝 Teacher's Note: Use the analogy of a highway with lanes going in both directions. Ask students to think of examples like facial nerves that control both sensation and muscle movement.

🎯 Exam Tip: The key word is "mixed" - it must contain both types of fibers. Don't confuse with nerves serving multiple organs.

Very Short Answer Type:

Question 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.
Answer:
(a) Cerebrospinal fluid
(b) Synapse
(c) Cerebrum
(d) Hypothalamus
In simple words: These are basic brain components - fluid for protection, gaps for signal transmission, cerebrum for thinking and memory, and hypothalamus as the body's thermostat.

📝 Teacher's Note: Connect each structure to everyday analogies - CSF as cushioning, synapse as a relay station, cerebrum as the computer processor, hypothalamus as a thermostat.

🎯 Exam Tip: Learn the specific functions - don't confuse cerebrum with cerebellum, and remember hypothalamus controls temperature regulation among other functions.

Question 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: ……………….
Answer:
(a) Stimulus: Receptor:: Impulse: Effectors
(b) Cerebrum: Diencephalon:: Cerebellum: Medulla oblongata
(c) Receptor: Sensory nerve:: Motor nerve: Effector
In simple words: These show the flow of nerve signals and brain organization - stimulus leads to receptor, impulse leads to effector; brain parts have their associated structures.

📝 Teacher's Note: Help students see the logical connections - stimulus-receptor (input), impulse-effector (output). Use brain diagrams to show anatomical relationships between structures.

🎯 Exam Tip: Identify the relationship pattern first, then apply it. Remember the nerve pathway: receptor → sensory nerve → CNS → motor nerve → effector.

Question 3. Complete the following statements by choosing the correct alternative from the choice 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 bosy
(ii) maintain posture and equilibrium
(iii) controlling thinking memory & reasoning
(c) Reflex action is controlled by
(i) brain (ii) spinal cord
(iii) autonomic (iii) peripheral nervous system
Answer:
(a) Sensory
(b) Maintaining posture and equilibrium
(c) Spinal cord
In simple words: Dorsal root carries sensory signals in, cerebellum keeps you balanced like a gyroscope, and spinal cord handles quick reflexes without involving the brain.

📝 Teacher's Note: Use mnemonics - "Dorsal = sensory Detection," "Cerebellum = balance Coordination." Demonstrate reflexes to show spinal cord's role without brain involvement.

🎯 Exam Tip: Remember dorsal = back = sensory input, ventral = front = motor output. Cerebellum is always about balance and coordination, not thinking.

Short Answer Type:

Question 1. Mention where in human bosy are the following located and state their main function:
(a) corpus callosum
(b) central canal
Answer:
(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.
In simple words: Corpus callosum is like a bridge connecting the left and right brain halves, while the central canal is like a protective fluid-filled tunnel running through the spinal cord.

📝 Teacher's Note: Show brain cross-sections highlighting the corpus callosum as the white matter bridge. Explain how split-brain patients demonstrate its importance in hemisphere communication.

🎯 Exam Tip: Always mention location AND function for full marks. Corpus callosum = connects hemispheres, central canal = CSF protection and nutrient exchange.

Question 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
(b) The arachnoid layer fits closely inside the pia mater.
(c) A double chain of ganglia, one on each side of the nerve cord belongs to the spinal cord.
(d) Dura mater is the outermost layer of the meninges.
Answer:
(a) False
(b) False
(c) True
(d) True
In simple words: White matter contains axons not cell bodies, arachnoid is between dura and pia mater, ganglia chains run alongside spinal cord, and dura mater is the tough outer brain covering.

📝 Teacher's Note: Use diagrams to show brain tissue composition and meningeal layers. Emphasize the order: dura (tough outer), arachnoid (web-like middle), pia (delicate inner).

🎯 Exam Tip: Remember white matter = axons (myelinated), grey matter = cell bodies. Meningeal order: "DAP" - Dura, Arachnoid, Pia from outside to inside.

Question 3. Differentiate between following pairs with reference to the aspect in brackets.
(a) cerebrum and cerebellum (function)
(b) sympathetic nervous system and para - sympathetic nervous system (overall effect on body)
(c) Sensory nerve and motor nerve (direction of impulse carried)
(d) medulla oblongata & cerebellum (function)
(e) cerebrum and spinal cord (arrangement of cytons and exons of neurons).
Answer:

In simple words: Brain and spinal cord have opposite arrangements - brain has grey matter outside (like bark on a tree), spinal cord has grey matter inside (like tree core).

📝 Teacher's Note: Use the "fight or flight" vs "rest and digest" analogy for autonomic nervous systems. Draw cross-sections showing the inverted grey/white matter arrangement between brain and spinal cord.

🎯 Exam Tip: Always mention the specific aspect asked in brackets. For nerve direction, use arrows: sensory → CNS, CNS → motor. Remember brain and spinal cord have opposite tissue arrangements.

Question 4. Given below are two structures, write their special functional activity.
(a) cerebellum and …………….
(b) Myelin sheath and ……………
Answer:
(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.
In simple words: Cerebellum is like your body's balance system, and myelin sheath is like insulation tape around electrical wires to prevent short circuits.

📝 Teacher's Note: Demonstrate balance activities to show cerebellum function. Use electrical wire analogies to explain myelin's insulating role and how it speeds up nerve conduction.

🎯 Exam Tip: Always link structure to function. Cerebellum = balance/coordination, myelin = insulation/speed. These are key functions to remember for exams.

Question 5. Write the functions of the following:
(a) synapse (b) Association neuron
(c) medullary sheath (d) Medulla obiongata
(e) cerebellum (f) Cerebrospinal fluid
Answer:
(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.
In simple words: These structures work together like a complex communication and protection system - synapses relay messages, association neurons connect pathways, sheaths insulate, medulla controls vital functions, cerebellum maintains balance, and CSF provides cushioning.

📝 Teacher's Note: Create a nerve pathway diagram showing how all these structures work together. Emphasize the protective and communication roles of different components.

🎯 Exam Tip: Learn one key function for each structure. Group them by function: protection (CSF, myelin), communication (synapse, association neuron), control (medulla, cerebellum).

Question 6. what do we refer to in the nervous system when we say:
(a) sensory, motor and mixed ………………..
(b) somatic and autonomic ……………………
(c) Natural and conditioned ………………
(d) sensory, motors and association ……………….
(e) Gray and white ………………………………
Answer:
(a) Sensory, motor and mixed nerves
(b) Somatic and autonomic nervous system
(c) Natural and conditioned reflexes
(d) Sensory, motor and association neurons
(e) Gray and white matter
In simple words: These are different ways to classify nervous system components - by nerve types, system divisions, reflex types, neuron types, and tissue types based on appearance and function.

📝 Teacher's Note: Create classification charts for each category. Use examples students can relate to - like conditioned reflexes (Pavlov's dog) vs natural reflexes (knee jerk).

🎯 Exam Tip: These are classification questions - match the number of categories given. Three types = nerves/neurons, two types = systems/reflexes/matter.

Question 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….. (polarised) (during conduction of nerve impulse through a nerve fibre)
(c) axon endings ……… nucleus …….. Dendrites ……… axon…….. perikaryon ………. Dendron……. (Neutron structure)
(d) diencephalon ………. Cerebellum …….. medulla oblongata ………. Pons ….. Cerebrum ……. mid-brain (sequence of parts of human brain).
Answer:
(a) Stimulus --- receptor --- sensory neuron --- central nervous system --- motor neuron --- effector --- response
(b) Resting --- depolarization --- repolarization
(c) Nucleus --- perikaryon --- dendron --- dendrites --- axon --- axon endings
(d) Cerebrum --- diencephalon --- mid-brain --- pons --- cerebellum --- medulla oblongata
In simple words: These sequences show nerve signal flow, electrical changes in nerve fibers, neuron structure from center outward, and brain organization from top to bottom.

📝 Teacher's Note: Draw flowcharts for each sequence. Use anatomical models to show brain part arrangement and neuron structure organization.

🎯 Exam Tip: Follow logical flow - reflex arc goes stimulus to response, nerve impulse follows electrical changes, neuron structure goes from cell body outward, brain follows anatomical position top to bottom.

Long Answer Type

Question 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 …………….
Answer: (a) Reflex action is an autonomic, quick and involuntary action in the body brought about by a stimulus.

(b)

In simple words: Reflex actions are instant reactions our body makes without thinking, like pulling your hand away from fire. Some are natural from birth (simple reflexes), while others we learn through practice (conditioned reflexes).

📝 Teacher's Note: Use examples students can relate to - have them test the knee-jerk reflex or pupil response to light. Explain that simple reflexes protect us, while conditioned reflexes help us learn skills.

🎯 Exam Tip: Always categorize reflexes clearly as "simple" or "conditioned" and provide the definition. Mention that reflex actions are controlled by the spinal cord, not the brain.

Question 2. What are the advantages of having a nervous system?
Answer: 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.
In simple words: The nervous system is like our body's control center and communication network - it helps us sense the world, think, move voluntarily, and keeps vital functions running automatically.

📝 Teacher's Note: Compare the nervous system to a computer with input devices (senses), processing unit (brain), and output devices (muscles). This analogy helps students understand coordination.

🎯 Exam Tip: Structure your answer with clear points (a), (b), (c), (d) and mention both voluntary and involuntary functions to show complete understanding.

Question 3. Why do you call the spinal cord and the brain as the central nervous system?
Answer: 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.
In simple words: The brain and spinal cord are called "central" because they're the main headquarters that receive all messages from the body and send back instructions - like a central command center.

📝 Teacher's Note: Emphasize the protective bony covering (skull and vertebral column) which shows how important these organs are. Use the analogy of a city's control room.

🎯 Exam Tip: Mention the anatomical protection (skull, vertebral column) and functional importance (control center) to get full marks.

Question 4. What is the difference between reflex action and voluntary action?
Answer: 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.

In simple words: Reflex actions happen automatically without thinking (like blinking), while voluntary actions need conscious decision-making (like writing or walking).

📝 Teacher's Note: Have students demonstrate both types - ask them to blink deliberately (voluntary) vs. shine a light to make them blink automatically (reflex).

🎯 Exam Tip: Always include examples and mention the control centers - spinal cord for reflexes, brain for voluntary actions.

Question 5. Draw a labelled diagram of a myelinated neuron.
Answer: [The diagram shows a myelinated neuron with the following labeled parts: Dendrites, Nissl's granules, Nucleus, Cell body, Schwann cell, Axon, Myelin Sheath, Nodes of Ranvier, Axon terminal, Synaptic knob]
In simple words: A neuron is like an electrical wire with branches (dendrites) to receive signals, a control center (cell body), and a long cable (axon) covered in insulation (myelin) to send messages quickly.

📝 Teacher's Note: Use the analogy of electrical cables - myelin sheath is like plastic insulation that speeds up nerve signals. Point out how dendrites "collect" and axon "delivers" messages.

🎯 Exam Tip: Label all parts clearly and remember that myelinated neurons conduct impulses faster than non-myelinated ones due to the myelin sheath.

Question 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 for you as an example).
Answer:

In simple words: During a fight, your body prepares for action - heart beats faster, pupils widen to see better, and mouth goes dry because digestion stops (sympathetic system works).

📝 Teacher's Note: Explain "fight or flight" vs. "rest and digest" responses. Students can relate to feeling their heart race during exams or scary situations.

🎯 Exam Tip: Remember that sympathetic prepares for action (increases activity) while parasympathetic promotes rest (decreases activity).

Structured / Application/Skill Type

Question 1. Two hungry boys (A and B) enter a restaurant and find a table decorated as follows: Boy B starts salivating but not A. Explain the reason for this difference.
Answer: 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.
In simple words: Boy B's mouth waters because his brain remembers eating that food before, while Boy A has never tasted it, so his brain doesn't trigger the salivation response.

📝 Teacher's Note: Connect this to Pavlov's dog experiment. Students can relate to their own experiences - how they salivate seeing their favorite food but not unfamiliar dishes.

🎯 Exam Tip: Always mention "conditioned reflex" and "prior experience/learning" when explaining situations involving memory-based responses.

Question 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?
Answer:

In simple words: Your body automatically adjusts to different situations - pupils widen in darkness to see better, heart slows for sleep, and muscles get energy during exercise.

📝 Teacher's Note: Help students understand the pattern: sympathetic for "action/stress" situations, parasympathetic for "rest/digestion" situations. Use daily life examples.

🎯 Exam Tip: Remember the rule: Sympathetic for emergency/action responses, Parasympathetic for routine/rest responses. Always mention the specific change in the organ.

Question 3. Given below is the partially incomplete scheme of the components of peripheral nervous system. Fill up the blanks numbered (1) - (8):
Answer: Fill in the following information in the diagram.
1 Central Nervous System
2 - Autonomic
3 - 12
4 - spinal
5 - 31
6 - dilates
7 - constricts
8 - liver
In simple words: The peripheral nervous system has two main parts: one that controls voluntary movements (somatic) and one that controls automatic body functions (autonomic).

📝 Teacher's Note: Draw the complete nervous system hierarchy on board. Emphasize the numbers: 12 cranial nerves, 31 spinal nerves - these are important facts students should memorize.

🎯 Exam Tip: Remember the key numbers: 12 cranial nerves, 31 spinal nerves. Know the difference between somatic (voluntary) and autonomic (involuntary) systems.

Review Questions

Multiple Choice Type

Question 1. Which part of the eye is grafted in a needy patient from a donated eye?
(a) Conjunctiva
(b) Cornea
(c) Choroid
(d) Ciliary muscles
Answer: (b) Cornea
In simple words: The cornea is the clear front layer of the eye that can be successfully transplanted from donor eyes to help blind people see again.

📝 Teacher's Note: Explain that cornea transplant is common because it has no blood vessels, reducing rejection risk. Connect to the importance of eye donation awareness.

🎯 Exam Tip: Remember that cornea is the only eye part commonly transplanted because it lacks blood supply, making rejection less likely.

Question 2. Which part of our ear is shaped like a snail shell?
(a) Semi circular canals
(b) Cochlea
(c) Stapes
(d) Eustachian tube
Answer: (b) Cochlea
In simple words: The cochlea is a spiral-shaped part in your inner ear that looks exactly like a snail's shell, which helps you hear sounds.

📝 Teacher's Note: Show students a real snail shell to help them visualize the cochlear structure. This visual analogy makes the complex inner ear anatomy more memorable for students.

🎯 Exam Tip: Remember "Cochlea = Coil like a snail" — this simple rhyme helps you recall the correct answer quickly during exams.

Question 3. The three parts of human ear contributing in hearing are
(a) cochlea, ear ossicles and tympanum
(b) semicircular canals, utriculus and sacculus
(c) eutachian tube, tympanum and utriculus
(d) perilymph, ear ossicle and semicircular canals
Answer: (a) cochlea, ear ossicles and tympanum
In simple words: The eardrum catches sound waves, the tiny ear bones amplify them, and the cochlea converts them into signals your brain understands.

📝 Teacher's Note: Explain the hearing pathway as a relay race — tympanum receives, ossicles pass on, and cochlea processes. This sequential understanding helps students grasp the concept better.

🎯 Exam Tip: Remember the hearing trio: "Tympanum catches, Ossicles amplify, Cochlea converts" — all three work together for hearing.

Question 4. The region in the eyes where the rods and cones are located is the
(a) retina
(b) cornea
(c) choroid
(d) sclera
Answer: (a) retina
In simple words: The retina is like the camera film of your eye where all the light-sensing cells (rods and cones) are located.

📝 Teacher's Note: Compare the retina to a camera's sensor or film — it captures the image. Students can relate this to their smartphone cameras for better understanding.

🎯 Exam Tip: "Retina = Rods and cones" — both start with 'R', making this an easy memory trick for exams.

Very Short Answer Type

Question 1. Name the following:
(a) The photosensitive pigment present in the rods of the retina.
(b) The part which equalizes the air pressure in the middle and external ear.
(c) The ear ossicle attached to the tympanum
(d) The outermost covering layer of the brain
(e) The tube which connects the cavity of the middle ear with the throat
(f) The part of the eye responsible for its shape.
(g) The nerves which transmit impulse from ear to the brain
(h) The photoreceptors found in the retina of the eye.
(i) The eye defect caused due to shortening of the eye ball from front to back.
Answer:
(a) Rhodopsin
(b) Eustachian tube
(c) Hammer
(d) Dura mater
(e) Eustachian tube
(f) Cornea
(g) Auditory nerves
(h) Rods and cones
(i) Hypermetropia
In simple words: These are specific names for different parts of our eyes, ears, and brain that help us see, hear, and stay protected.

📝 Teacher's Note: Create flashcards with these terms and functions. Students often confuse similar-sounding names, so repeated practice with visual aids helps retention.

🎯 Exam Tip: Learn the exact spellings — marks are often deducted for misspelled scientific terms like "rhodopsin" and "hypermetropia".

Question 2. Note the relationship between the first two words and suggest the suitable word/words for the fourth place.
(a) Cones : Iodopsim :: Rods : ……………….
(b) sound : ear drum :: Dynamic balance : ……
Answer:
(a) Cones: Iodopsin:: rods: rhodopsin
(b) Sound: ear drum:: dynamic balance: semi-circular canals
In simple words: Just as cones have iodopsin pigment, rods have rhodopsin pigment; and just as ear drum detects sound, semicircular canals detect body balance.

📝 Teacher's Note: Emphasize the analogy format — students need to understand the relationship pattern before filling the blanks. Practice more such analogies for better comprehension.

🎯 Exam Tip: Always identify the relationship first (structure:function or part:pigment), then apply the same pattern to find the answer.

Question 3. Which one or more of the expressions in column II are appropriate for the items listed in column I? write the correct matching pairs

Answer: As shown in the table above.
In simple words: Each part of the eye and brain has specific functions — blind spot has no sensors, yellow spot is the center for clear vision, and so on.

📝 Teacher's Note: Use labeled diagrams of the eye while teaching this matching. Visual correlation with function helps students remember these associations better.

🎯 Exam Tip: Learn the key functions: blind spot = no vision, yellow spot = best vision, iris = eye color — these are frequently tested.

Short Answer Type

Question 1. Differentiate between members of each of the following pairs with reference to what is asked in brackets.
(a) Myopia and hyperopia (cause of the defect)
(b) Rods and cones (sensitivity)
(c) Semi-circular canal and cochlea (Senses perceived)
(d) Rod and cone cells (pigment contained)
(e) Dynamic balance and static balance (Definition)
Answer:
(a) Myopia results when the eye ball is lengthened from front to back or the lens is too curved. Hyperopia results from either too shortening of the eyeball from front to back or when the lens is too flat.
(b) Rods are sensitive to dim light but do not respond to colour. Cones are sensitive to bright light and are responsible for colour vision.
(c) Cochlea is responsible for hearing; it can perceive the senses of hearing. Semicircular canals are responsible for perceiving the senses to maintain the body balance.
(d) Rod cells contain rhodopsin whereas the cone cells contain iodopsin.
(e) Dynamic balance is when the body is in motion whereas static balance is positional balance with respect to gravity.
In simple words: These pairs show opposite conditions or different functions — like nearsighted vs farsighted, dim light vs bright light sensors, hearing vs balance, and moving vs still balance.

📝 Teacher's Note: Use simple demonstrations — cover one eye for monocular vision, spin students gently to show balance sensors working. Hands-on experience reinforces theoretical knowledge.

🎯 Exam Tip: Structure your answers clearly with "A causes this while B causes that" format — examiners appreciate clear comparisons.

Question 2. State whether the following statements are True (t) or False, correct them by changing any one single word in each.
(a) Deafness is caused due to rupturing of the pinna
(b) Semi circular canals are concerned with static (positional) balance.
Answer:
(a) False. Correct statement: Deafness is caused due to rupturing of the eardrum.
(b) False. Correct statement: Semicircular canals are concerned with dynamic balance.
In simple words: The eardrum is what actually gets damaged to cause deafness, and semicircular canals help with balance when you're moving, not when you're still.

📝 Teacher's Note: Emphasize that only ONE word should be changed. Students often change multiple words and lose marks unnecessarily.

🎯 Exam Tip: Read the instruction carefully — "change any one single word" means exactly one word replacement, not multiple changes.

Question 3. Mention, where in living organisms are the following located and state their main functions:
(a) Fovea centralis (b) Organ of corti
Answer:
(a) Fovea centralis is located at the back of the eye almost at the centre of the eyeball. It is the region of the brightest vision and also of the colour vision.
(b) Organ of corti is located in the inner ear. It contains sensory cells which process hearing.
In simple words: Fovea centralis is the "sweet spot" in your eye for the sharpest, clearest vision, while organ of corti is the actual hearing processor in your ear.

📝 Teacher's Note: Relate fovea centralis to the center of a target — that's where you get the best "hit" or clearest vision. This analogy helps students remember its function.

🎯 Exam Tip: Always mention both location AND function when asked — incomplete answers get partial marks only.

Question 4. Mention if the following statements are true (T) or false (F) Give reason.
(a) Sometimes medicines dropped into the eyes come into the nose and even throat
(b) Ciliary muscles regulate the size of the pupil
(c) yellow spot of the retina is the region of colour vision
(d) The auditory nerve is purely for perceiving sound
(e) Malleus incus and stapes are collectively called the ear ossicles
(f) Flavour and taste are one and the same thing.
(g) short-sightedness and hyperopia are one and the same thing
(h) Blind spot is called so because no image is formed on it.
Answer:
(a) True
(b) False. Ciliary muscles regulate the size of the lens.
(c) True
(d) False. The auditory nerve responsible for sound as well as for the body balance.
(e) True
(f) False. flavour is a combination of taste and smell.
(g) False. short-sightedness is myopia and hyperopia is long-sightedness.
(h) True
In simple words: Most statements are about correcting common misconceptions — like ciliary muscles change lens shape not pupil size, and flavor involves both taste and smell together.

📝 Teacher's Note: Address common student misconceptions systematically. Many students confuse ciliary muscle function and mix up myopia/hyperopia terminologies.

🎯 Exam Tip: When stating "False," always provide the correct version immediately — this shows complete understanding and earns full marks.

Question 5. Given below are two sets (a) and (b) of five parts in each. Rewrite them in correct sequence.
(a) Cochlea, tympanum, auditory canal, ear ossicles, oval window.
(b) Conjunctiva, retina, cornea, optic nerve, lens
Answer:
(a) Auditory canal, tympanum, ear ossicles, oval window, cochlea
(b) Conjunctiva, cornea, lens, retina, optic nerve
In simple words: These show the path sound and light take — sound goes from ear canal to eardrum to tiny bones to cochlea, while light goes from outer eye covering to cornea to lens to retina to brain.

📝 Teacher's Note: Teach these as pathways or journeys. Students understand sequences better when they visualize the actual path of stimuli through the organs.

🎯 Exam Tip: Remember the flow: for ear "Canal→Drum→Bones→Window→Cochlea" and for eye "Outside→Front→Focus→Back→Brain"

Question 6. Given below are certain structures. Write against them their functional acivity.
(a) organ of corti and ……………….
(b) Olfactory nerve and …………….
(c) retina and ……………………….
(d) Taste bud and ……………………..
Answer:
(a) Organ of Corti and hearing
(b) Olfactory nerve and smell
(c) Retina and vision
(d) Taste bud and taste
In simple words: Each structure has one main job — hearing, smelling, seeing, and tasting respectively.

📝 Teacher's Note: Connect structure names to their functions using word associations — "olfactory" sounds like "smell factory" which helps students remember.

🎯 Exam Tip: Keep answers short and direct — one word functions are usually sufficient for such questions.

Question 7. Answer the following:
(a) What is a lacrimal gland?
(b) In what two ways is the yellow spot different from the blind spot?
(c) Name an old age eye defect. What happens in it?
(d) What is meant by power of accommodation of the eye?
(e) Mention the characteristics of the image that falls on the retina of the eye.
Answer:
(a) Lacrimal gland is a tear gland located at the upper sideward portion of the eye orbit. Its secreation lubricates the surface of the eye, washes always the dust particles and kills germs
(b) Yellow spot is the region of brightest vision and contains maximum sensory cells whereas a blind spot contains no sensory cells and this is the point of no vision.
(c) Presbyopia is an age-old eye defect. In this condition, the lens loses flexibility resulting in far-sightedness. Cataract is also very common in old people, the cornea becomes opaque and the vision is cut down even to blindness.
(d) The process of focusing the eye at different distances is called the power of accommodation.
(e) The image formed on the retina is inverted and real.
In simple words: These answers cover how our eyes protect themselves with tears, see clearly at one spot, develop problems with age, adjust focus, and create upside-down real images.

📝 Teacher's Note: Demonstrate accommodation by having students focus on their finger moving closer and farther from their face — they can feel the lens adjusting.

🎯 Exam Tip: For part (c), mention both presbyopia and cataract to show comprehensive knowledge of age-related eye problems.

Question 8. What is meant by optical illusion? Give one example.
Answer: An optical illusion is the life-like continuous movement on the screen. Television is an example of optical illusion, where the scanning beam of a picture frame of the TV camera moves so rapidly on the viewing screen of the TV set that our eyes cannot keep pace with it.
In simple words: Optical illusion is when our eyes see something that isn't really there — like movies appearing to move when they're just still pictures shown very fast.

📝 Teacher's Note: Use flipbook animation or fast-moving images to demonstrate how still pictures create the illusion of movement when shown rapidly.

🎯 Exam Tip: Always provide a clear example with your definition — TV, movies, or flipbooks are good examples of optical illusions.

Question 9. Where are the following located? Briefly mention the function of each:
(a) oval window (b) Cochlea
Answer: The question appears incomplete as the answer for this question is not provided in the given content.
In simple words: This question asks about ear parts and their jobs, but the complete answer isn't shown in the material.

📝 Teacher's Note: When answers are incomplete, encourage students to research and complete them using textbooks or reliable sources.

🎯 Exam Tip: If you encounter incomplete questions in study materials, always verify answers from multiple sources before exams.

Question. (c) Semicircular canals (d) Utriculus
Answer: (a) Oval window is located in the middle ear. It helps in setting the fluid in the cochlear canals into vibration.
(b) Cochlea is located in the inner ear. It helps in transmitting impulses to the brain via the auditory nerve.
(c) Semicircular canals are located in the inner ear. These help in maintaining the dynamic equilibrium of the body.
(d) Utriculus is located in the inner ear. It joins the semi-circular canals to cochlea. It also helps in maintaining static balance of the body.
In simple words: These are all parts of the ear that help us hear sounds and keep our balance when we move around.

📝 Teacher's Note: Use a model of the ear to show the physical locations of these structures. Students often confuse where each part is located and what it does.

🎯 Exam Tip: Remember the locations - oval window is in middle ear, while cochlea, semicircular canals, and utriculus are all in inner ear. Know their specific functions for full marks.

Question. Name the four principal tastes and the respective regions of the tongue concerned with their perception.
Answer: The four principal tastes are sweet, salt, bitter and sour.
In simple words: Our tongue can taste four main flavors - sweet (like sugar), salt (like in chips), bitter (like medicine), and sour (like lemon).

📝 Teacher's Note: Show the tongue diagram and let students taste safe examples of each taste. The regions are: sweet at tip, salt at sides front, sour at sides back, bitter at back.

🎯 Exam Tip: Just listing the four tastes gets full marks here. If asked about regions, draw a simple tongue diagram with labeled areas.

Question. Complete the following table by filling in the blank spaces.
Answer:

In simple words: Each part of our nervous system has a specific job - like the yellow spot gives us the clearest vision, and semicircular canals help us keep our balance.

📝 Teacher's Note: Create a matching exercise where students connect structures to functions before filling the table. This builds understanding of structure-function relationships.

🎯 Exam Tip: Learn the exact function names - "region of brightest vision" not just "vision", "conducts impulses" not just "carries signals".

Long Answer Type

Question. Describe the mechanism of focusing the image of a distant object in your eye when you raise your head after reading a book.
Answer: While reading a book, the lens is more convex or rounded due to contraction of ciliary muscles because the book is usually read from a short distance. When we raise our head and look at a distant object, the ciliary muscles relax to build the tension on the suspensory ligament so that they can stretch the lens. This change in the curvature of the lens makes us focus on distant object.
In simple words: When reading, our eye lens becomes thick to see close things. When we look far away, the muscles relax and the lens becomes thin to see distant things clearly.

📝 Teacher's Note: Use a magnifying glass to demonstrate how changing lens shape affects focus. Have students try the exercise of looking from book to distant object to feel the accommodation.

🎯 Exam Tip: Mention both states - lens convex/thick for near vision, lens stretched/thin for distant vision. Always explain the role of ciliary muscles and suspensory ligaments.

Question. Sometimes you remember a vivid picture of a dream you saw. What is the role of your eyes in this experience?
Answer: The brain sees the vivid picture of the dream through the eyes. Our eyes have actually never seen the vivid picture. This is an example of optical illusion. The area of dream is controlled by the cerebrum of the central nervous system. So sometime we can remember the vivid picture seen in the dream.
In simple words: When we dream, our brain creates pictures without our eyes actually seeing anything - it's like our brain is making its own movie while we sleep.

📝 Teacher's Note: Explain that dreams show how the brain processes visual information independently of actual light input. Connect to how we can imagine pictures with eyes closed.

🎯 Exam Tip: Key points - eyes don't actually see dream images, brain creates the visual experience, cerebrum controls dreams, this is an optical illusion.

Question. By closing the eyes and gently pressing them by your palms, you may see some specks of brilliant light. How do you get this sensation while there is no light entering your eyes?
Answer: If we look at a bright object and then close our eyes, the sensation of light persists for a short period. This is known as persistence image or the after image. It lasts for one-tenth of a second. Therefore by closing the eyes and gently pressing them with your palms, you see some specs of brilliant light.
In simple words: After seeing bright light, our eyes keep "seeing" it for a short time even when closed - like an echo but for vision instead of sound.

📝 Teacher's Note: Demonstrate with a camera flash or bright light. Students can safely try pressing gently on closed eyelids to experience phosphenes (pressure-induced light sensations).

🎯 Exam Tip: Use the term "persistence of vision" or "after image" and mention the duration (one-tenth of a second). Explain it's due to continued nerve stimulation.

Question. Explain the terms 'adaptation' and 'accommodation' with reference to the eye.
Answer: Adaptation is the ability to adjust vision in bright and dark areas. When we enter a dark room from bright light, the rhodopsin pigment broken down in bright light is regenerated. It dilates the pupil and allows more light to enter the eyes. This is called dark adaptation. On the other hand, if we enter bright area from a dark room, the rhodopsin pigment is bleached. This constricts the pupil and reduces the light entering the eyes. This is called 'light adaptation'
Accommodation is the process of focusing the eye at different distances. This is mainly brought about by a change in the curvature of the lens. When the ciliary muscles contract, the lens becomes thicker and we are able to focus a nearby object. On the other hand when the ciliary muscles relax, the lens remains stretched i.e. the normal condition and we are able to focus on distant object.
In simple words: Adaptation is how our eyes adjust to bright or dark places (like pupils getting bigger in darkness). Accommodation is how our eyes focus on near or far things (by changing lens shape).

📝 Teacher's Note: Take students from bright classroom to dark room to experience adaptation. Use examples like entering cinema hall or stepping outside on sunny day.

🎯 Exam Tip: Don't confuse these terms. Adaptation = adjusting to light intensity (pupil and rhodopsin). Accommodation = focusing at different distances (lens shape and ciliary muscles).

Question. You do not enjoy watching a movie from a very short distance from the screen in a cinema hall. Why?
Answer: Our eyes are designed to focus at a great variety of distances. To focus constantly at a short distance can make the lens focusing muscles fatigued. Therefore, we do not enjoy watching a movie from a very short distance from the screen in cinema hall.
In simple words: Sitting too close to the movie screen makes our eye muscles work too hard to focus, which makes our eyes tired and uncomfortable.

📝 Teacher's Note: Relate to students' experience of eye strain from sitting too close to TV or computer screens. Emphasize the importance of maintaining proper viewing distance.

🎯 Exam Tip: Focus on muscle fatigue as the main cause. Mention that eyes are designed for varied distances, not constant close focus.

Question. Enumerate the common defects of vision, their causes and the possible methods of correcting them.
Answer:

In simple words: Eyes can have different problems like seeing near or far clearly, having cloudy lenses, or not seeing colors properly - most can be fixed with glasses or surgery.

📝 Teacher's Note: Use simple diagrams to show how different lens shapes correct different defects. Discuss that some defects are more common with age (presbyopia, cataract).

🎯 Exam Tip: Remember lens types - concave for myopia (nearsightedness), convex for hyperopia (farsightedness). Note that color blindness has no cure.

Question. Name the three ear ossicles. How do they contribute in the mechanism of hearing?
Answer: The three ear ossicles are: Malleus (hammer), Incus (anvil) and Stapes (stirr up). The last ear ossicle, stapes, vibrates and transmits the vibration to the oval window. The role of other two ear ossicles is to magnify the vibration of stapes as a result of their lever like action.
In simple words: Three tiny bones in our ear (hammer, anvil, stirrup) work together like levers to make sound vibrations stronger before sending them to the inner ear.

📝 Teacher's Note: Use the common names (hammer, anvil, stirrup) to help students remember. Demonstrate lever action with simple tools to show how small movements can be amplified.

🎯 Exam Tip: Give both scientific names (malleus, incus, stapes) and common names (hammer, anvil, stirrup). Explain their lever action amplifies vibrations.

Question. What is meant by power of accommodation of the eye? Name the muscles of the eye responsible for the same.
Answer: The process of focusing the eye at different distances is called the power of accommodation. The ciliary muscles are responsible for the power of accommodation.
In simple words: Power of accommodation is our eye's ability to automatically adjust focus from near to far objects, controlled by ciliary muscles.

📝 Teacher's Note: Have students practice looking at their finger close to their face, then at the classroom wall. They can feel the accommodation happening automatically.

🎯 Exam Tip: Define accommodation clearly and always mention ciliary muscles as responsible. This is a common 2-mark question.

Structured / Application / Skill Type

Question. With reference to the functioning of the eye, answer the questions that follow:
(a) What is meant by power of accommodation of the eye?
(b) What is the shape of the lens during (1) near vision (2) distant vision?
(c) Name the two structure in the eye responsible for bringing about the change in the shape of the lens.
(d) Name the cells of the retina and their respective pigments which get activated (1) in the dark and (2) in the light.
Answer: (a) The ability of the eye to focus sharply on things which are near to the eye as well as far off is known as the power of accommodation.
(b) Shape of the eye: Near vision - flattened, Distant - rounded or more convex
(c) Ciliary muscles and suspensory ligament
(d) In the dark: Cells - rod cells, Pigment - rhodopsin; In the light: Cells - cone cells, Pigment - iodopsin
In simple words: Our eyes can automatically focus near and far by changing lens shape using muscles and ligaments, with different cells working in bright and dim light.

📝 Teacher's Note: This question tests multiple concepts together. Break it down and ensure students understand each part before combining them in answers.

🎯 Exam Tip: Note the lens shape reversal - many students confuse this. Near vision needs thick/convex lens, distant vision needs flattened lens. Remember rod-rhodopsin (dark), cone-iodopsin (light).

Question. With reference to the human ear, answer the questions that follow:
Answer: (This appears to be an incomplete question in the source material)
In simple words: This question would typically ask about ear structure and function.

📝 Teacher's Note: Use ear models and diagrams to teach the three parts of ear (outer, middle, inner) and their specific functions in hearing and balance.

🎯 Exam Tip: Always specify which part of the ear (outer, middle, inner) when answering questions about ear structures and their functions.

Question. Give the technical term for the structure found in the inner ear. Name the three small bones present in the middle ear. What is the biological term for them collectively? Name the part of the ear associated with (1) static balance (2) hearing (3) dynamic balance. Name the nerve, which transmits messages from the ear to the brain.
Answer: (a) The middle ear or membranous labyrinth has two structures inside it, the cochlea and the semi-circular canals. (b) Malleus, incus and stapes. Collectively they are termed as ossicles. (c) Static balance - Utriculus and sacculus (inner ear), Hearing - Internal ear, Dynamic balance - Semi-circular canals (inner ear). (d) Auditory nerve.
In simple words: The inner ear has special structures like the cochlea for hearing and semicircular canals for balance. Three tiny bones in the middle ear work together to amplify sound vibrations.

📝 Teacher's Note: Use a model or diagram to show how the three ear bones work like a lever system to amplify sound. Students often confuse the location of these structures, so emphasize middle ear vs inner ear clearly.

🎯 Exam Tip: Remember the sequence: malleus (hammer), incus (anvil), stapes (stirrup) - use the memory trick "MIS" for the order. Always mention "collectively called ossicles" for full marks.

Question. The figure below compares a part of our eye with a part of a photographic camera. Name the corresponding parts of the eye the camera shown here that are comparable in function. Explain the mode of working and the functions of the parts of the eye mentioned above.
Answer: (a) Cornea is comparable to the lens cover of the camera. The iris and pupil act like the aperture of a camera. (b) The cornea is the eye's main focusing element. It takes widely diverging rays of light and bends them through the pupil; the rays are further converged by the lens.
In simple words: The eye works like a camera - the cornea acts like the outer lens cover, while the iris and pupil control how much light enters, just like a camera's aperture opening and closing.

📝 Teacher's Note: Demonstrate with an actual camera or smartphone camera to show aperture changes. Students relate better when they can see the iris dilating and contracting in different light conditions.

🎯 Exam Tip: Always mention both parts of the comparison - eye part AND camera part - with their functions. Use terms like "converging" and "diverging" for light rays to show understanding.

Question. Given below is a diagram depicting a defect of the human eye. Study the same and answer the questions that follow: Name the defect shown in the diagram. Give two possible reasons for this defect. Name the parts labelled 1 to 4. Name the type of lens used to correct this eye defect. Draw a labelled diagram to show how the above mentioned defect is rectified using the lens named above.
Answer: (a) Myopia (b) The two possible reasons for myopia are either the eye ball is lengthened from front to back or the lens is too curved. (c) 1 - vitreous humour, 2 - blind spot, 3 - lens, 4 - pupil (d) Concave lens (e) [Diagram showing concave lens correcting myopia]
In simple words: Myopia (short-sightedness) happens when the eyeball is too long or the lens is too curved, making distant objects blurry. A concave lens spreads out light rays before they enter the eye, fixing the problem.

📝 Teacher's Note: Use the analogy of a camera being "out of focus" - the image forms in front of the film instead of on it. Show how concave lenses diverge light rays using a simple ray diagram.

🎯 Exam Tip: Remember: Myopia = distant objects blurry = concave lens correction. Always draw the corrected ray diagram showing image forming exactly on the retina for full marks.

Question. The figure below is the sectional view of a part of the skull showing a sense organ: Name the sense organ. What are the parts labelled 'm', "I" and "s"? What do these three parts constitute collectively? What do you call the part shown in the form of a spiral? What is its function? Name the part labelled "tm"? What is its function?
Answer: (i) Ear (ii) m - malleus, i - incus and s - stapes respectively. These are collectively called as ear ossicles. (iii) Cochlea. The vibrating movements in the hair of the sense cells of cochlea transmit the impulse for hearing to the brain via auditory nerve. (iv) Tympanic membrane. It vibrates and then sets the ear ossicles into vibration in the process of hearing.
In simple words: The ear has three tiny bones that work like a chain reaction - the eardrum vibrates, which moves the bones, which creates waves in the spiral-shaped cochlea that sends hearing signals to the brain.

📝 Teacher's Note: Demonstrate the vibration chain using tuning forks or by tapping on desks. Students should understand the mechanical to electrical signal conversion in the cochlea.

🎯 Exam Tip: Always mention the complete pathway: tympanic membrane → ossicles → cochlea → auditory nerve → brain. Use proper terminology like "hair cells" and "impulses" for full credit.

Question. Given below is the diagram of a part of the human ear. Study the same and answer the questions that follow: Give the collective biological term for malleus, Incus and stapes. Name the parts labelled A, B, and C in the diagram. State the functions of the parts labelled 'A' and 'B'. Name the audio receptor region present in the part labelled 'A'.
Answer: (i) Ear ossicles (ii) A - Cochlea, B - Semicircular canals, C - Ear ossicles (iii) Cochlea helps in transmitting impulses to the brain via the auditory nerve. Semicircular canals help in maintaining dynamic equilibrium of the body. (iv) Organ of Corti
In simple words: The cochlea detects sound and sends signals to the brain, while the semicircular canals help you keep your balance when moving. The Organ of Corti is like the "microphone" inside the cochlea.

📝 Teacher's Note: Compare semicircular canals to a spirit level used in construction - they detect when your head tilts or rotates. The Organ of Corti is the actual sound detector inside the cochlea.

🎯 Exam Tip: Distinguish between static balance (utriculus/sacculus) and dynamic balance (semicircular canals). Always name "Organ of Corti" as the specific audio receptor, not just "cochlea".

Question. Draw a labelled diagram of the inner ear. Name the part of the inner ear that is responsible for static balance in human beings.
Answer: [Diagram provided showing semicircular canals, ampulla, auditory nerve, utriculus, ear drum, ear ossicles (malleus, incus, stapes), sacculus, and cochlea] Utriculus and Sacculus are responsible for maintaining static balance in human beings.
In simple words: The utriculus and sacculus are like tiny spirit levels in your ear that tell your brain whether you're upright, tilted, or upside down when you're not moving.

📝 Teacher's Note: Explain that static balance is for stationary positions while dynamic balance is for movement. Use the example of standing on one foot (static) vs walking on a balance beam (dynamic).

🎯 Exam Tip: Draw a clear, well-labelled diagram with all major parts visible. Specifically mention both "utriculus AND sacculus" - don't write just one of them.

Question. Have a look at the posture of this girl who is reading a book and answer the questions which follow: Name the problem she is facing. What are the two conditions shown in sections A and B of the eye as applicable to her. What kind of looking glasses she needs?
Answer: (a) Myopia (b) A - Normal eye, B - Myopia (c) Looking glasses with the concave lens are required here.
In simple words: The girl is holding the book too close because she has myopia (short-sightedness) - she can see nearby things clearly but distant things are blurry. Concave lenses will help her see far objects clearly.

📝 Teacher's Note: Use this image to discuss proper reading posture and eye care. Emphasize the 20-20-20 rule: every 20 minutes, look at something 20 feet away for 20 seconds.

🎯 Exam Tip: When comparing normal vs defective vision, always mention which condition shows normal image formation on the retina vs in front of/behind the retina. Link the correction directly to the type of lens needed.