Part 1: Neurons and Nerve Impulse
200 MCQs step by step from Chapter 21 – Neural Control and Coordination (NCERT Class 11 Biology, important for CBSE + NEET UG).
Subtopic as per NCERT + NEET relevance
- Neurons and Nerve Impulse – Structure of neuron, types, nerve impulse conduction, synapse, neurotransmitters
- Central Nervous System (CNS) – Brain – Forebrain, midbrain, hindbrain, functions of brain parts, meninges, cerebrospinal fluid
- Spinal Cord – Structure, functions, reflex actions, reflex arc
- Peripheral Nervous System (PNS) – Cranial nerves, spinal nerves, somatic and autonomic nervous system
- Autonomic Nervous System (ANS) – Sympathetic vs parasympathetic, differences, functions
- Sense Organs – Eye – Structure, physiology of vision, photoreceptor cells
- Sense Organs – Ear – Structure, physiology of hearing and balance
- Integrated & Miscellaneous NEET-level Questions – Assertion-reason, application-based, mixed difficulty
Part 1: Neurons and Nerve Impulse
Q1. The structural and functional unit of the nervous system is:
a) Axon
b) Neuron
c) Dendrite
d) Nucleus
Answer: b) Neuron
Explanation:
- ✅ (b) Neuron is the basic functional unit.
- (a) Axon = part of neuron.
- (c) Dendrite = branch for signals.
- (d) Nucleus = inside cell body.
Q2. Myelin sheath is formed by:
a) Schwann cells and oligodendrocytes
b) Astrocytes
c) Microglia
d) Ependymal cells
Answer: a) Schwann cells and oligodendrocytes
Explanation:
- ✅ (a) Schwann cells in PNS, oligodendrocytes in CNS form myelin.
- Others provide support, immunity, CSF lining.
Q3. Nodes of Ranvier are:
a) Gaps in myelin sheath
b) Axon terminals
c) Synaptic clefts
d) Nucleus of neuron
Answer: a) Gaps in myelin sheath
Explanation:
- ✅ (a) Nodes = unmyelinated gaps → saltatory conduction.
Q4. Which ion enters neuron during depolarization?
a) Na⁺
b) K⁺
c) Cl⁻
d) Ca²⁺
Answer: a) Na⁺
Explanation:
- ✅ (a) Sodium influx → depolarization.
Q5. Which ion leaves neuron during repolarization?
a) Na⁺
b) K⁺
c) Cl⁻
d) Ca²⁺
Answer: b) K⁺
Explanation:
- ✅ (b) K⁺ efflux → restores resting potential.
Q6. Resting membrane potential of a neuron is about:
a) +70 mV
b) –70 mV
c) –90 mV
d) 0 mV
Answer: b) –70 mV
Explanation:
- ✅ (b) Inside of neuron is negative (–70 mV).
Q7. The conduction of nerve impulse across synapse is mainly:
a) Electrical
b) Chemical
c) Both
d) None
Answer: b) Chemical
Explanation:
- ✅ (b) Most synapses = chemical (via neurotransmitters).
Q8. Acetylcholine is broken down by:
a) Acetylcholinesterase
b) ATPase
c) Tyrosinase
d) Peptidase
Answer: a) Acetylcholinesterase
Explanation:
- ✅ (a) Rapid breakdown of ACh in synaptic cleft.
Q9. Which part of neuron receives impulses?
a) Axon
b) Dendrites
c) Axon terminals
d) Synapse
Answer: b) Dendrites
Explanation:
- ✅ (b) Dendrites → receive incoming signals.
Q10. Saltatory conduction occurs in:
a) Non-myelinated axons
b) Myelinated axons
c) Dendrites
d) Cell body
Answer: b) Myelinated axons
Explanation:
- ✅ (b) Impulse jumps from one Node of Ranvier to another.
Q11. Which neurotransmitter is excitatory at neuromuscular junction?
a) Dopamine
b) Acetylcholine
c) GABA
d) Serotonin
Answer: b) Acetylcholine
Explanation:
- ✅ (b) ACh stimulates muscle contraction.
Q12. Inhibitory neurotransmitter in CNS is:
a) Glutamate
b) GABA
c) Acetylcholine
d) Norepinephrine
Answer: b) GABA
Explanation:
- ✅ (b) GABA = main inhibitory neurotransmitter.
Q13. Speed of impulse conduction is greatest in:
a) Thin unmyelinated axon
b) Thick myelinated axon
c) Dendrites
d) Cell body
Answer: b) Thick myelinated axon
Explanation:
- ✅ (b) Thick + myelinated = fastest conduction.
Q14. Synaptic cleft width is about:
a) 2–4 nm
b) 20–40 nm
c) 200–400 nm
d) 2 µm
Answer: b) 20–40 nm
Explanation:
- ✅ (b) Gap between pre- and post-synaptic membranes.
Q15. Resting potential is maintained by:
a) Na⁺–K⁺ pump
b) Ca²⁺ pump
c) ATP synthase
d) Na⁺–Cl⁻ pump
Answer: a) Na⁺–K⁺ pump
Explanation:
- ✅ (a) Active transport: 3 Na⁺ out, 2 K⁺ in.
Q16. During action potential, threshold potential is about:
a) –55 mV
b) –70 mV
c) –90 mV
d) +30 mV
Answer: a) –55 mV
Explanation:
- ✅ (a) Depolarization begins once threshold (~–55 mV) is reached.
Q17. The refractory period ensures:
a) Impulse travels in one direction only
b) Impulse reverses
c) Depolarization increases
d) ATP not required
Answer: a) Impulse travels in one direction only
Explanation:
- ✅ (a) Refractory period prevents backflow.
Q18. Myelin sheath increases conduction velocity by:
a) Continuous conduction
b) Saltatory conduction
c) Chemical conduction
d) Random diffusion
Answer: b) Saltatory conduction
Explanation:
- ✅ (b) Jumps between nodes = faster conduction.
Q19. Which part of neuron is absent in myelinated axons?
a) Axon
b) Nodes of Ranvier
c) Continuous conduction
d) Cell body
Answer: c) Continuous conduction
Explanation:
- ✅ (c) Saltatory replaces continuous conduction.
Q20. Neurotransmitters are released from:
a) Dendrites
b) Axon terminals
c) Cell body
d) Myelin sheath
Answer: b) Axon terminals
Explanation:
- ✅ (b) Vesicles release neurotransmitters at terminals.
Q21. Which ion triggers release of neurotransmitter at synapse?
a) Na⁺
b) K⁺
c) Ca²⁺
d) Cl⁻
Answer: c) Ca²⁺
Explanation:
- ✅ (c) Ca²⁺ influx at presynaptic terminal triggers exocytosis.
Q22. White matter in CNS consists mainly of:
a) Neuron cell bodies
b) Myelinated axons
c) Dendrites
d) Neuroglia only
Answer: b) Myelinated axons
Explanation:
- ✅ (b) White matter = myelinated fibers.
Q23. Gray matter in CNS consists mainly of:
a) Axons
b) Myelinated fibers
c) Neuron cell bodies and dendrites
d) Neuroglia only
Answer: c) Neuron cell bodies and dendrites
Explanation:
- ✅ (c) Gray matter = soma + dendrites.
Q24. Which ion imbalance may block action potential generation?
a) Na⁺
b) K⁺
c) Ca²⁺
d) All of these
Answer: d) All of these
Explanation:
- ✅ (d) Any imbalance affects nerve impulse conduction.
Q25. The main function of dendrites is:
a) Conduct impulses away from cell body
b) Receive signals and carry them to cell body
c) Release neurotransmitters
d) Form myelin sheath
Answer: b) Receive signals and carry them to cell body
Explanation:
- ✅ (b) Dendrites → receive → send toward soma.
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