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| Diagram showing conduction of nerve impulse through an axon by movement of sodium and potassium ions. |
NEET-Level MCQs: Neural Control & Coordination
Topic: Impulse Conduction Through Axon (Hard Level)
MCQ 1
During depolarisation of an axonal membrane:
A. K⁺ ions rapidly enter the axoplasm
B. Na⁺ ions rapidly diffuse into the axoplasm
C. Cl⁻ ions move outside the membrane
D. Na⁺ ions are actively transported outside
Answer:
✅ B. Na⁺ ions rapidly diffuse into the axoplasm
Explanation:
Depolarisation occurs due to opening of voltage-gated Na⁺ channels causing rapid Na⁺ influx.
MCQ 2
The resting membrane potential in a neuron is mainly due to:
A. Equal permeability to Na⁺ and K⁺
B. Higher permeability to Na⁺ than K⁺
C. Differential distribution of ions across membrane
D. Active transport of Cl⁻ ions only
Answer:
✅ C. Differential distribution of ions across membrane
Explanation:
Unequal distribution of Na⁺ and K⁺ ions creates resting membrane potential.
MCQ 3
Which of the following correctly represents the charge distribution during resting state?
| Outside | Inside |
|---|---|
| A. Negative | Positive |
| B. Positive | Positive |
| C. Positive | Negative |
| D. Negative | Negative |
Answer:
✅ C. Positive outside, Negative inside
MCQ 4
In repolarisation of nerve membrane:
A. Na⁺ enters the neuron
B. K⁺ exits the neuron
C. Ca²⁺ enters the neuron
D. Cl⁻ exits the neuron
Answer:
✅ B. K⁺ exits the neuron
MCQ 5
The sodium-potassium pump transports:
A. 2 Na⁺ out and 3 K⁺ in
B. 3 Na⁺ out and 2 K⁺ in
C. 3 K⁺ out and 2 Na⁺ in
D. Equal Na⁺ and K⁺ ions
Answer:
✅ B. 3 Na⁺ out and 2 K⁺ in
MCQ 6
The action potential at one point of axon causes depolarisation at adjacent point because:
A. Hormones diffuse locally
B. Local electrical currents are generated
C. Axoplasm becomes acidic
D. ATP concentration increases
Answer:
✅ B. Local electrical currents are generated
MCQ 7
The refractory period is mainly caused by:
A. Continuous Na⁺ influx
B. Opening of Ca²⁺ channels
C. Temporary inactivation of Na⁺ channels
D. Excess ATP production
Answer:
✅ C. Temporary inactivation of Na⁺ channels
MCQ 8
Saltatory conduction occurs in:
A. Non-myelinated fibres
B. Dendrites only
C. Myelinated nerve fibres
D. Cell body only
Answer:
✅ C. Myelinated nerve fibres
Explanation:
Impulse jumps from one node of Ranvier to another.
MCQ 9
Which event immediately follows depolarisation?
A. Hyperpolarisation
B. Repolarisation
C. Resting potential
D. Synaptic transmission
Answer:
✅ B. Repolarisation
MCQ 10
The inside of axonal membrane becomes positively charged during:
A. Resting state
B. Repolarisation
C. Depolarisation
D. Refractory period
Answer:
✅ C. Depolarisation
Assertion & Reason Type
MCQ 11
Assertion (A):
Impulse conduction in myelinated fibres is faster.
Reason (R):
Depolarisation occurs only at nodes of Ranvier.
A. Both A and R are true and R is correct explanation
B. Both A and R are true but R is not correct explanation
C. A true but R false
D. A false but R true
Answer:
✅ A
MCQ 12
Assertion (A):
During resting state, axonal membrane is polarised.
Reason (R):
Na⁺ permeability is higher than K⁺ permeability during resting condition.
Answer:
✅ C. A is true but R is false
Explanation:
At rest, membrane is more permeable to K⁺.
Match the Following
MCQ 13
| Column I | Column II |
|---|---|
| a. Depolarisation | 1. K⁺ efflux |
| b. Repolarisation | 2. Na⁺ influx |
| c. Resting potential | 3. Polarised membrane |
| d. Saltatory conduction | 4. Myelinated fibres |
Correct Match:
a → 2
b → 1
c → 3
d → 4
Statement-Based MCQ
MCQ 14
Which statements are correct?
- Resting membrane is negatively charged outside.
- Depolarisation occurs due to Na⁺ influx.
- Repolarisation occurs due to K⁺ efflux.
- Action potential travels in one direction.
A. 1 and 2 only
B. 2, 3 and 4 only
C. 1, 3 and 4 only
D. All are correct
Answer:
✅ B
Higher-Order NEET MCQ
MCQ 15
If voltage-gated Na⁺ channels fail to open in a neuron, then:
A. Resting potential increases
B. Repolarisation becomes faster
C. Action potential cannot be generated
D. K⁺ influx increases
Answer:
✅ C. Action potential cannot be generated
NEET PYQ-Type MCQ
MCQ 16
The membrane potential of a resting nerve fibre depends mainly upon:
A. Diffusion of Na⁺ and K⁺ ions
B. Active transport of ions
C. Ionic permeability of membrane
D. All of these
Answer:
✅ D. All of these
Very Hard Conceptual MCQ
MCQ 17
Conduction velocity in myelinated fibres increases because:
A. Entire membrane depolarises simultaneously
B. Current leakage is prevented by myelin sheath
C. Na⁺ channels remain permanently open
D. ATP consumption stops completely
Answer:
✅ B
Diagram-Based MCQ
MCQ 18
In the figure of impulse conduction, point A becomes depolarised first because:
A. K⁺ channels open first at A
B. Na⁺ permeability increases at A
C. ATP synthesis increases at A
D. Cl⁻ ions enter at A
Answer:
✅ B
NCERT Line-Based MCQ
MCQ 19
The electrical potential difference across resting plasma membrane is called:
A. Synaptic potential
B. Resting potential
C. Threshold potential
D. End plate potential
Answer:
✅ B
MCQ 20
Which ion is mainly responsible for restoring resting membrane potential after action potential?
A. Na⁺
B. Ca²⁺
C. K⁺
D. Cl⁻
Answer:
✅ C. K⁺
NEET Previous Year Questions (PYQs)
Topic: Neural Control & Coordination – Nerve Impulse Conduction
PYQ 1 — NEET 2023
The membrane potential of a resting neuron is mainly maintained by:
A. Diffusion of Na⁺ only
B. Diffusion of K⁺ only
C. Sodium-potassium pump
D. Calcium pump
Answer:
✅ C. Sodium-potassium pump
Explanation:
The Na⁺/K⁺ pump actively transports:
- 3 Na⁺ outside
- 2 K⁺ inside
This maintains resting membrane potential.
PYQ 2 — NEET 2022
During generation of action potential:
A. K⁺ enters the neuron
B. Na⁺ enters the neuron
C. Cl⁻ enters the neuron
D. Na⁺ exits the neuron
Answer:
✅ B. Na⁺ enters the neuron
Explanation:
Opening of voltage-gated Na⁺ channels causes depolarisation.
PYQ 3 — NEET 2021
Saltatory conduction of nerve impulse occurs in:
A. Non-myelinated nerve fibres
B. Smooth muscles
C. Myelinated nerve fibres
D. Dendrites
Answer:
✅ C. Myelinated nerve fibres
Explanation:
Impulse jumps from one node of Ranvier to another.
PYQ 4 — NEET 2020
At resting stage, the outer surface of axonal membrane possesses:
A. Negative charge
B. Positive charge
C. Neutral charge
D. Alternating charges
Answer:
✅ B. Positive charge
PYQ 5 — NEET 2019
Which ion channels open during depolarisation?
A. Voltage-gated K⁺ channels
B. Voltage-gated Na⁺ channels
C. Calcium channels
D. Chloride channels
Answer:
✅ B. Voltage-gated Na⁺ channels
PYQ 6 — NEET 2018
Repolarisation of neuronal membrane occurs due to:
A. Influx of Na⁺
B. Efflux of K⁺
C. Influx of Ca²⁺
D. Efflux of Cl⁻
Answer:
✅ B. Efflux of K⁺
PYQ 7 — AIIMS/NEET Pattern
The resting potential across neuronal membrane is approximately:
A. +70 mV
B. 0 mV
C. –70 mV
D. –120 mV
Answer:
✅ C. –70 mV
PYQ 8 — NEET Pattern
The region between two myelin sheath segments is called:
A. Schwann cell
B. Synaptic cleft
C. Node of Ranvier
D. Axolemma
Answer:
✅ C. Node of Ranvier
PYQ 9 — NEET 2017
The membrane of a resting nerve cell is more permeable to:
A. Na⁺
B. K⁺
C. Ca²⁺
D. Cl⁻
Answer:
✅ B. K⁺
PYQ 10 — NEET 2016
Which of the following is true regarding nerve impulse transmission?
A. Impulse travels randomly
B. Impulse conduction is faster in non-myelinated fibres
C. Impulse conduction in myelinated fibres is saltatory
D. Resting membrane is depolarised
Answer:
✅ C. Impulse conduction in myelinated fibres is saltatory
PYQ 11 — AIPMT Pattern
The depolarisation of neuronal membrane is caused by:
A. Entry of Na⁺
B. Exit of Na⁺
C. Entry of K⁺
D. Exit of K⁺
Answer:
✅ A. Entry of Na⁺
PYQ 12 — NEET Pattern
Which structure forms myelin sheath in peripheral nervous system?
A. Astrocytes
B. Microglia
C. Schwann cells
D. Oligodendrocytes
Answer:
✅ C. Schwann cells
PYQ 13 — NEET Pattern
In mammals, the nerve fibres that conduct impulses fastest are:
A. Non-myelinated fibres
B. Thin fibres
C. Myelinated fibres
D. Dendrites
Answer:
✅ C. Myelinated fibres
PYQ 14 — NEET Pattern
The action potential generated during nerve impulse is due to:
A. Reversal of membrane polarity
B. Permanent loss of membrane permeability
C. Breakdown of plasma membrane
D. Loss of ATP
Answer:
✅ A. Reversal of membrane polarity
PYQ 15 — Most Repeated NEET Concept
Which statement is correct?
A. Resting membrane is depolarised
B. Repolarisation occurs due to Na⁺ influx
C. Depolarisation occurs due to Na⁺ influx
D. K⁺ influx causes action potential
Answer:
✅ C. Depolarisation occurs due to Na⁺ influx
Important PYQ Revision Table
| Concept | Key Ion |
|---|---|
| Resting Potential | K⁺ permeability high |
| Depolarisation | Na⁺ influx |
| Repolarisation | K⁺ efflux |
| Saltatory Conduction | Myelinated fibres |
| Resting Potential Value | –70 mV |
NEET Rapid Revision Tricks
“Na IN = Depolarisation”
Na⁺ enters → inside becomes positive
“K OUT = Repolarisation”
K⁺ exits → inside becomes negative again
“Myelin = Fast”
Myelinated fibres conduct impulses faster
NEET Full Mock Test
Chapter: Neural Control & Coordination
Topic: Nerve Impulse Conduction & Neuron
Total Questions: 45
Level: NEET Exam Standard
SECTION A — MCQs
Q1.
The resting membrane potential is mainly due to:
A. Equal distribution of ions
B. Unequal distribution of ions
C. Entry of proteins
D. Absence of ATP
Q2.
During depolarisation:
A. K⁺ enters the neuron
B. Na⁺ enters the neuron
C. Cl⁻ enters the neuron
D. K⁺ exits the neuron
Q3.
The membrane potential of resting neuron is approximately:
A. +70 mV
B. –70 mV
C. –120 mV
D. 0 mV
Q4.
The sodium-potassium pump transports:
A. 2 Na⁺ out, 3 K⁺ in
B. 3 Na⁺ out, 2 K⁺ in
C. 3 K⁺ out, 2 Na⁺ in
D. Equal ions both sides
Q5.
Repolarisation occurs because:
A. Na⁺ enters
B. K⁺ exits
C. Ca²⁺ enters
D. Cl⁻ enters
Q6.
Myelin sheath in PNS is formed by:
A. Astrocytes
B. Oligodendrocytes
C. Schwann cells
D. Microglia
Q7.
Saltatory conduction occurs in:
A. Dendrites
B. Non-myelinated fibres
C. Myelinated fibres
D. Cell body
Q8.
The gap between myelin sheath is:
A. Synapse
B. Node of Ranvier
C. Axolemma
D. Neurolemma
Q9.
The inside of resting axon is:
A. Positive
B. Neutral
C. Negative
D. Alternating
Q10.
Action potential is generated due to:
A. Loss of ATP
B. Reversal of membrane polarity
C. Entry of proteins
D. Water movement
Q11.
Which ion is more permeable during resting condition?
A. Na⁺
B. K⁺
C. Ca²⁺
D. Cl⁻
Q12.
Impulse transmission in myelinated fibres is faster because:
A. Continuous depolarisation
B. No ion movement
C. Jumping conduction
D. Less ATP
Q13.
Voltage-gated Na⁺ channels open during:
A. Resting state
B. Repolarisation
C. Depolarisation
D. Hyperpolarisation
Q14.
Which restores resting potential?
A. Na⁺ influx
B. K⁺ efflux
C. Protein synthesis
D. Ca²⁺ influx
Q15.
The membrane of resting neuron is:
A. Depolarised
B. Polarised
C. Neutralised
D. Hyperexcited
Assertion & Reason
Q16.
Assertion: Myelinated fibres conduct impulses rapidly.
Reason: Impulse jumps between nodes.
A. Both true and reason correct
B. Both true but incorrect explanation
C. Assertion true, reason false
D. Both false
Q17.
Assertion: Depolarisation occurs due to Na⁺ influx.
Reason: Na⁺ channels open during stimulation.
A. Both true and reason correct
B. Both true but incorrect explanation
C. Assertion true, reason false
D. Both false
Q18.
Assertion: Resting membrane is negatively charged outside.
Reason: K⁺ permeability is higher than Na⁺.
A. Both true
B. Assertion false, reason true
C. Both false
D. Assertion true, reason false
Match the Following
Q19.
| Column I | Column II |
|---|---|
| a. Depolarisation | 1. K⁺ exit |
| b. Repolarisation | 2. Na⁺ entry |
| c. Saltatory conduction | 3. Myelin sheath |
| d. Resting state | 4. Polarised membrane |
A. a-2, b-1, c-3, d-4
B. a-1, b-2, c-4, d-3
C. a-2, b-3, c-1, d-4
D. a-4, b-1, c-2, d-3
Higher Order Thinking Questions
Q20.
If Na⁺ channels fail to open:
A. Repolarisation increases
B. Action potential will not occur
C. K⁺ influx increases
D. Resting potential disappears
Q21.
Direction of impulse is maintained because:
A. Neurons are circular
B. Previous region is refractory
C. ATP is absent
D. K⁺ cannot move
Q22.
The refractory period prevents:
A. Repolarisation
B. Backward conduction
C. Saltatory conduction
D. ATP synthesis
Q23.
Which structure receives stimulus first?
A. Axon
B. Synapse
C. Dendrite
D. Node
Q24.
The functional gap between two neurons is:
A. Axon hillock
B. Synapse
C. Schwann cell
D. Neurolemma
Q25.
Chemical released at synapse:
A. Hormone
B. Enzyme
C. Neurotransmitter
D. Protein
Q26.
Acetylcholine is:
A. Hormone
B. Neurotransmitter
C. Enzyme
D. Pigment
Q27.
Impulse conduction in non-myelinated fibres is:
A. Saltatory
B. Faster
C. Continuous
D. Absent
Q28.
Node of Ranvier contains:
A. Lipids only
B. Voltage-gated ion channels
C. DNA
D. Ribosomes
Q29.
Which cell forms myelin sheath in CNS?
A. Schwann cell
B. Astrocyte
C. Oligodendrocyte
D. Microglia
Q30.
The threshold stimulus:
A. Produces maximum impulse
B. Produces minimum impulse needed
C. Stops depolarisation
D. Causes repolarisation
NEET PYQ-Based Questions
Q31.
Resting potential is:
A. +70 mV
B. –70 mV
C. 0 mV
D. –140 mV
Q32.
During action potential:
A. Inner side becomes positive
B. Outer side becomes positive
C. Both sides neutral
D. No change
Q33.
Myelin sheath acts as:
A. Insulator
B. Hormone
C. Enzyme
D. Neurotransmitter
Q34.
The speed of impulse depends on:
A. Axon diameter
B. Myelination
C. Temperature
D. All of these
Q35.
Neurotransmitter diffuses across:
A. Node
B. Synaptic cleft
C. Axoplasm
D. Dendrite
Diagram/Concept Questions
Q36.
Depolarisation means:
A. Positive outside
B. Negative inside only
C. Reversal of polarity
D. Loss of membrane
Q37.
Repolarisation restores:
A. Action potential
B. Resting condition
C. Synapse
D. Neurotransmitter
Q38.
The axoplasm contains:
A. Cytoplasm of axon
B. Blood plasma
C. Cerebrospinal fluid
D. Hormones
Q39.
Impulse conduction requires:
A. Ion movement
B. Oxygen only
C. Water only
D. Lipids only
Q40.
All-or-none law means:
A. Strong impulse only
B. Weak impulse only
C. Either complete impulse or none
D. Variable response
Very Hard NEET Questions
Q41.
Hyperpolarisation occurs due to:
A. Excess Na⁺ entry
B. Excess K⁺ exit
C. Protein movement
D. Ca²⁺ influx
Q42.
Fastest conducting neurons possess:
A. Thin non-myelinated axons
B. Thick myelinated axons
C. Dendrites only
D. No nodes
Q43.
The electrochemical gradient of Na⁺ causes:
A. Na⁺ entry during depolarisation
B. K⁺ entry during resting state
C. ATP breakdown
D. Water loss
Q44.
Synaptic transmission is mostly:
A. Electrical only
B. Chemical only
C. Both electrical and chemical
D. Hormonal
Q45.
A neuron unable to repolarise would:
A. Remain depolarised
B. Stop ATP production
C. Lose dendrites
D. Produce hormones
ANSWER SHEET
| Q | Ans | Q | Ans | Q | Ans |
|---|---|---|---|---|---|
| 1 | B | 16 | A | 31 | B |
| 2 | B | 17 | A | 32 | A |
| 3 | B | 18 | B | 33 | A |
| 4 | B | 19 | A | 34 | D |
| 5 | B | 20 | B | 35 | B |
| 6 | C | 21 | B | 36 | C |
| 7 | C | 22 | B | 37 | B |
| 8 | B | 23 | C | 38 | A |
| 9 | C | 24 | B | 39 | A |
| 10 | B | 25 | C | 40 | C |
| 11 | B | 26 | B | 41 | B |
| 12 | C | 27 | C | 42 | B |
| 13 | C | 28 | B | 43 | A |
| 14 | B | 29 | C | 44 | C |
| 15 | B | 30 | B | 45 | A |
Internal Links
Human Neural System Complete Notes
Synapse and Neurotransmitters NEET Guide
Reflex Action and Reflex Arc Notes
Central Nervous System Explained
Myelinated vs Non-Myelinated Neurons
Sodium Potassium Pump NEET Notes
NEET Biology Chapterwise MCQs
Neural Control and Coordination PYQs
Structure of Neuron Easy Notes
Endocrine System Complete Revision Notes
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