Nervous System - Competency-Based Question Bank (with Answers)

Section A: Case-Based Questions

Case Study 1: Accidentally touching a hot pan and withdrawing hand.

1. Identify the action.
   • Answer: Reflex Action.
2. Trace the pathway.
   • Answer: Receptor (Skin) -> Sensory Neuron -> Spinal Cord -> Motor Neuron -> Effector (Muscle).
3. Designing: Schematic diagram.
   • Answer: [Description: Arc shape connecting skin to spinal cord and back to muscle].
4. Analysis: Why withdrawal before pain?
   • Answer: The reflex arc is local to the spinal cord for speed. The message to the brain (pain perception) travels through a longer path and takes slightly more time.
5. Damaged motor neuron?
   • Answer: The person will feel the pain (sensory works) but will not be able to move the hand (effector fails).

Case Study 2: Elderly person with Parkinson's (lack of Dopamine). 6. What is a "Synapse"?

• Answer: The microscopic gap between the axon terminal of one neuron and the dendrite of the next.

7. Role of neurotransmitters.
   • Answer: They are chemicals (like Acetylcholine or Dopamine) released from vesicles that diffuse across the synapse to transmit the impulse to the next neuron.
8. Creating: Analogy.
   • Answer: Like a relay race where the baton (neurotransmitter) is handed from one runner to the next at the exchange zone (synapse).
9. Critical Thinking: Why one direction?
   • Answer: Vesicles containing neurotransmitters are only present at the axon terminals, and receptors are only present on the dendrites.
10. Resting vs Action Potential.
    • Answer: Resting: Neuron is not conducting (-70mV). Action: Reversal of polarity (+30mV) during conduction of an impulse.

Section B: Assertion-Reasoning Questions

Directions: (a) Both A/R true, R explains A; (b) Both true, R doesn't explain A; (c) A true, R false; (d) A false, R true.

11. Assertion (A): Cerebellum controls balance. Reason (R): It coordinates muscular activity.
    • Answer: (a) Both A and R are true and R is the correct explanation.
12. Assertion (A): Medulla Oblongata is vital. Reason (R): It controls involuntary activities.
    • Answer: (a) Both A and R are true and R is the correct explanation.
13. Assertion (A): Rod cells responsible for dim light vision. Reason (R): They contain Rhodopsin.
    • Answer: (a) Both A and R are true and R is the correct explanation.
14. Assertion (A): Blind spot is area of best vision. Reason (R): It has maximum Cones.
    • Answer: (d) A is false but R is true (in definition of fovea, but for blind spot, both are false). Correct Answer: (d) A is false. (Blind spot has no photoreceptors).
15. Assertion (A): Myopia corrected by concave lens. Reason (R): Concave lens diverges light.
    • Answer: (a) Both A and R are true and R is the correct explanation.

Section C: Creating and Designing (Application & Analysis)

16. Designing: Nervous System classification.
    • Answer: CNS (Brain, Spinal Cord) and PNS (Somatic, Autonomic: Sympathetic/Parasympathetic).
17. Creating: Eye User Manual (Accommodation).
    • Answer: For near objects: Ciliary muscles contract -> Suspensory ligaments slacken -> Lens becomes more convex. Opposite for far objects.
18. Analysis: Sympathetic vs Parasympathetic.
    • Answer: Sympathetic (Emergency): Increases heart rate, dilates pupil. Parasympathetic (Rest): Decreases heart rate, constricts pupil.
19. Designing: Cerebrum vs Cerebellum table.
    • Answer: Cerebrum: Large, memory/intellect, outer grey. Cerebellum: Small, balance/coordination, outer grey with tree-like white inside.
20. Visualisation: Neuron diagram.
    • Answer: [Description: Star-shaped cyton with a long tail]. Myelin sheath acts as insulation and increases speed of impulse (Saltatory conduction).
21. Application: Dizziness after spinning.
    • Answer: The fluid (endolymph) in the semicircular canals continues to move due to inertia even after the head stops, sending false signals to the brain.
22. Creating: Anosmia effect on taste.
    • Answer: Flavor is a combination of smell and taste. Without smell, food tastes bland and complex flavors cannot be distinguished.
23. Analysis: "All-or-None" law.
    • Answer: A stimulus must reach a threshold to trigger an impulse. Once triggered, the impulse always has the same strength regardless of the stimulus intensity.
24. Designing: Color Blindness test.
    • Answer: Use Ishihara plates (dots of different colors forming numbers).
25. Creating: Hearing path.
    • Answer: Sound -> Pinna -> Eardrum (Vibration) -> Hammer/Anvil/Stirrup (Amplification) -> Cochlea (Fluid waves) -> Auditory Nerve.

Section D: Competency & Critical Thinking

26. Gray vs White Matter.
    • Answer: Gray: Cytons and non-myelinated fibers. White: Myelinated axons. Brain: Gray outside. Spinal Cord: Gray inside (H-shape).
27. Scenario: Memory loss part.
    • Answer: Cerebrum (specifically the hippocampus/temporal lobes).
28. Critical Thinking: Inverted image perception.
    • Answer: The brain interprets the inverted image and "flips" it upright during processing.
29. Application: Presbyopia vs Hypermetropia.
    • Answer: Hypermetropia: Eyeball too short/lens too flat. Presbyopia: Loss of lens elasticity due to age. Both cause difficulty seeing near objects.
30. Natural vs Conditioned Reflex.
    • Answer: Natural: Inborn (e.g., blinking). Conditioned: Learned through experience (e.g., salivating at the sound of a bell).
31. Diagram Based: Eustachian tube.
    • Answer: It equalizes air pressure on both sides of the eardrum.
32. Corpus Callosum function.
    • Answer: It is a band of white fibers that allows communication between the left and right cerebral hemispheres.
33. Analysis: Binocular Vision advantage.
    • Answer: Provides depth perception (stereoscopic vision) because each eye sees from a slightly different angle.
34. Competency: Organ of Corti.
    • Answer: The sensory part of the cochlea containing hair cells that convert mechanical vibrations into electrical nerve impulses.
35. Case: Pupil constriction.
    • Answer: Pupillary Light Reflex. Controlled by the Iris (circular muscles).
36. Creating: Reaction time hypothesis.
    • Answer: Repeated practice strengthens neural pathways and improves coordination.
37. Designing: Path of light.
    • Answer: Conjunctiva -> Cornea -> Aqueous Humor -> Pupil/Lens -> Vitreous Humor -> Retina.
38. Application: Cochlear implants.
    • Answer: They bypass the ear and directly stimulate the auditory nerve with electrical signals.
39. Critical Thinking: Nerve cell regeneration.
    • Answer: Neurons lack centrosomes and cannot undergo mitosis. They have very limited regenerative capacity.
40. Analysis: Stereoscopic Vision.
    • Answer: Three-dimensional vision resulting from the fusion of two slightly different images.

Section E: Advanced Competency

41. Scenario: Stroke in left hemisphere.
    • Answer: Right side paralysis. Nerve fibers cross over in the Medulla (Decussation).
42. Designing: Model.
    • Answer: Wire (Axon), Tape (Myelin), Beads at ends (Terminals).
43. Application: Cataract.
    • Answer: Opacity of the lens. Treated by replacing the natural lens with an artificial IOL (Intraocular Lens).
44. Creating: Hormonal vs Nervous table.
    • Answer: [Nervous: Electrical, fast, short-lived, localized. Hormonal: Chemical, slow, long-lasting, widespread].
45. Case Study: Gymnast's brain part.
    • Answer: Cerebellum.
46. Threshold Stimulus.
    • Answer: The minimum intensity of a stimulus required to generate an action potential.
47. Critical Thinking: Smell and taste link.
    • Answer: Both use chemoreceptors and their information is combined in the brain to perceive flavor.
48. Analysis: Aqueous vs Vitreous Humor.
    • Answer: Aqueous (front): Nourishes cornea/lens. Vitreous (back): Maintains eyeball shape and supports retina.
49. Designing: Frequency graph.
    • Answer: 20 Hz to 20,000 Hz.
50. Creating: Bionic Eye features.
    • Answer: Sensors to detect light, a processor to convert to electrical signals, and electrodes to stimulate the optic nerve.