ICSE Class 10 Biology: Nervous System — Important Questions with Answers 2026

Short Answer Questions (2-3 Marks)

• Q: Draw a neat labelled diagram of a neuron and describe its parts.
  Ans: A neuron has: (1) Cell body (cyton) — contains nucleus, Nissl granules. (2) Dendrites — short, branched projections that receive impulses. (3) Axon — long fibre that transmits impulses away from cell body. Covered by myelin sheath (Schwann cells) with nodes of Ranvier. (4) Axon terminals (synaptic knobs) — terminal branches with synaptic vesicles containing neurotransmitters.
• Q: What is a synapse? How is a nerve impulse transmitted across it?
  Ans: A synapse is the microscopic gap (synaptic cleft) between the axon terminal of one neuron and the dendrite of the next neuron. Transmission: (1) Impulse reaches axon terminal. (2) Synaptic vesicles release neurotransmitter (acetylcholine) into synaptic cleft. (3) Neurotransmitter binds to receptors on next neuron's dendrite. (4) New impulse generated in the next neuron. (5) Enzyme (cholinesterase) breaks down neurotransmitter.
• Q: Differentiate between the central nervous system and peripheral nervous system.
  Ans: CNS: Consists of brain and spinal cord, protected by skull and vertebral column respectively, covered by meninges, processes and integrates information. PNS: Consists of cranial nerves (12 pairs from brain) and spinal nerves (31 pairs from spinal cord), connects CNS to body parts, carries impulses to and from CNS.

Long Answer / Application Questions (4-6 Marks)

• Q: Name the three parts of the human brain and state one function of each.
  Ans: (1) Cerebrum (forebrain): Largest part. Controls thinking, memory, intelligence, voluntary actions, sensory perception (sight, hearing, smell, taste, touch). Has two hemispheres. (2) Cerebellum (hindbrain): Controls balance, posture, coordination of voluntary movements. (3) Medulla oblongata (hindbrain): Controls involuntary actions — heartbeat, breathing, blood pressure, peristalsis, swallowing.
• Q: What is a reflex action? Describe the reflex arc.
  Ans: A reflex action is an automatic, quick, involuntary response to a stimulus without conscious thought. Example: pulling hand away from hot object. Reflex arc: Receptor (skin) → Sensory neuron → Relay neuron (in spinal cord) → Motor neuron → Effector (muscle). The impulse goes through the spinal cord, not the brain, enabling a faster response.

Exam Tips for This Chapter

• Revise all definitions and laws from Nervous System — they are commonly asked as 1-2 mark questions
• Practice diagrams related to Nervous System — neat labelled diagrams carry 2-3 marks
• For numericals, always show formula → substitution → answer with correct units
• Previous year analysis shows Nervous System carries 8-12 marks in the board exam