Molecular Basis of Excitability Practice Questions

Question 1

Assertion: RMP depends on proteins and phosphate ions.
Reason: Diffusion potential can be calculated using nernst equation.
Choose the best statement regarding the assertion and reason.

Accepted Answer

Both true, Reason is not the explanation of assertion

Answer

Assertion false, Reason true

Answer

Both true, Reason is the explanation of assertion

Answer

Assertion true, Reason false

Question 2

Sequence the events in neuromuscular action potential conduction:
1. Sodium channels open in the end plate
2. Calcium enters at the nerve terminal
3. Release of acetylcholine

Accepted Answer

$2 \rightarrow 3 \rightarrow 1$

Answer

$1 \rightarrow 2 \rightarrow 3$

Answer

$1 \rightarrow 3 \rightarrow 2$

Answer

$3 \rightarrow 2 \rightarrow 1$

Question 3

Which of the following statements about the Na-K pump is false?

Accepted Answer

It is located on the apical membrane of cell

Answer

It is not directly involved in the generation of action potentials.

Answer

It is electrogenic

Answer

It needs ATP for its functioning

Question 4

1 ml of 7.5% sodium bicarbonate provides:-

Accepted Answer

0.9 meq bicarbonate

Answer

0.5 meq bicarbonate

Answer

1.5 meq bicarbonate

Answer

1.1 meq bicarbonate

Question 5

Absolute refractoriness of a neuron is due to?

Accepted Answer

Inactivation of Na channels

Answer

Hyperpolarization of Cl channels

Answer

Opening of rectifier K+ channels

Answer

Closure of activated Na channels

Question 6

Which of these is true about the highlighted transporter?

Accepted Answer

One molecule goes in, other molecule goes out

Answer

Both molecules go in

Answer

Both molecules go out

Answer

One molecule goes in and two exit

Question 7

In multiple sclerosis, slow conduction of motor and sensory pathways is due to?

Accepted Answer

Loss of myelin sheath

Answer

Dysfunction of sodium channels

Answer

Dysfunction of calcium channels

Answer

Defect in the nodes of Ranvier

Question 8

Which part of the action potential in cardiac pacemaker cells is primarily affected by calcium channel blockers?

Accepted Answer

Phase 0

Answer

Phase 1

Answer

Phase 2

Answer

Phase 3

Question 9

Hyperpolarization is caused by which ions?

Accepted Answer

K+

Answer

Na+

Answer

HCO3-

Answer

Ca2+

Question 10

A novel drug is designed to treat a genetic disorder caused by a nonsense mutation in the dystrophin gene. The drug works by allowing the ribosome to skip over the premature stop codon and continue translation. Evaluation of this therapeutic strategy reveals partial restoration of dystrophin protein with 60% of normal length but sufficient function. What is the most critical molecular consideration in determining if this approach will be clinically beneficial?

Accepted Answer

Whether the truncated protein retains the actin-binding domain and maintains membrane stability

Answer

Whether the drug prevents degradation of dystrophin mRNA

Answer

Whether the drug enhances ribosomal binding to the start codon

Answer

Whether the drug increases transcription of the dystrophin gene

Molecular Basis of Excitability — MCQs

Molecular Basis of Excitability — MCQs

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