Neural Control and Coordination — Class 11 Biology NCERT Solutions (Free)

Free step-by-step NCERT solutions for Class 11 Biology chapter "Neural Control and Coordination" — 8 important questions with detailed answers for CBSE board exam preparation.

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TL;DR: Free step-by-step NCERT solutions for Class 11 Biology chapter "Neural Control and Coordination" — 8 important questions with detailed answers for CBS…

Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated Jul 23, 2026

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Key Questions Covered:

What is a neuron? Name its three main parts and their functions.
Differentiate between myelinated and unmyelinated nerve fibers.
Explain the all-or-none principle in nerve impulse transmission.
What is a synapse? Describe the mechanism of synaptic transmission.
Define reflex arc. Give an example of a spinal reflex.
What is the difference between the sympathetic and parasympathetic nervous sy…
+ 2 more questions in the full chapter

Solutions Summary:

Question	Status
What is a neuron? Name its three main parts and their fun…	✓ Solved
Differentiate between myelinated and unmyelinated nerve f…	✓ Solved
Explain the all-or-none principle in nerve impulse transm…	✓ Solved
What is a synapse? Describe the mechanism of synaptic tra…	✓ Solved
Define reflex arc. Give an example of a spinal reflex.	✓ Solved
What is the difference between the sympathetic and parasy…	✓ Solved

Showing 6 of 8 questions

Q1: What is a neuron? Name its three main parts and their functions.

Neuron is the structural and functional unit of nervous system. Three main parts: - Dendrite: receives signals from other neurons via neurotransmitters; increases surface area - Cell body (soma): contains nucleus; site of protein synthesis - Axon: transmits electrical signals away from cell body; ends in synaptic terminal

Q2: Differentiate between myelinated and unmyelinated nerve fibers.

Myelinated fibers: - Covered by myelin sheath formed by Schwann cells; segmented - Saltatory conduction (jump along nodes of Ranvier) - Conduction velocity: 100+ m/s - Found in somatic and autonomic nervous systems Unmyelinated fibers: - No myelin sheath; multiple axons embedded in single Schwann cell - Continuous conduction along entire axon - Conduction velocity: 0.5-2 m/s - Found in parasympathetic and visceral sensory nerves

Q3: Explain the all-or-none principle in nerve impulse transmission.

All-or-none principle: - If stimulus intensity reaches threshold, action potential fires completely - If stimulus is below threshold, no action potential occurs - Once threshold is reached, further stimulus increase does not alter magnitude of action potential - Intensity of stimulus is conveyed by frequency of action potentials, not by amplitude - This ensures reliable nerve signaling

Q4: What is a synapse? Describe the mechanism of synaptic transmission.

Synapse is junction between axon terminal of one neuron and dendrite/soma of next neuron. Synaptic transmission: - Action potential reaches presynaptic terminal - Voltage-gated Ca2+ channels open; Ca2+ influx - Synaptic vesicles fuse with membrane; neurotransmitter released - Neurotransmitter diffuses across synaptic cleft - Binds to receptors on postsynaptic membrane - Opens ion channels; depolarization or hyperpolarization occurs

Q5: Define reflex arc. Give an example of a spinal reflex.

Reflex arc is the pathway of nerve impulse in a reflex action from receptor to effector. Sequence: Receptor → sensory neuron → spinal cord → motor neuron → effector Example - withdrawal reflex on touching hot object: - Sensory receptors detect heat - Sensory neuron conducts impulse to spinal cord - Synapse with motor neuron in cord (no brain involvement) - Motor neuron sends impulse to flexor muscles - Arm withdraws immediately; pain sensation follows

Q6: What is the difference between the sympathetic and parasympathetic nervous systems?

Sympathetic nervous system: - Fight or flight response - Increases heart rate, BP, pupil dilation - Decreases digestion - Arises from thoracolumbar region Parasympathetic nervous system: - Rest and digest response - Decreases heart rate, BP - Increases digestion - Arises from craniosacral region - Generally antagonistic effects

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