- 1(current)
Q. No.Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R):
In the light of the above statements choose the correct answer from the options given below:
| Assertion (A): | Neurons are excitable cells. |
| Reason (R): | Their membranes are in a polarised state. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
Subtopic: Â Origin of Resting Membrane Potential |Â Action Potential |
 87%
Level 1: 80%+
Hints
When the neuron is not conducting any impulse, i.e., resting, the axonal membrane:
| 1. | is comparatively more permeable to sodium ions and nearly impermeable to potassium ions. |
| 2. | is freely permeable to sodium ions and potassium ions. |
| 3. | is impermeable to sodium ions and potassium ions. |
| 4. | is comparatively more permeable to potassium ions and nearly impermeable to sodium ions. |
Subtopic: Â Origin of Resting Membrane Potential |Â Action Potential |
 88%
Level 1: 80%+
Hints
The resting axonal membrane is impermeable to:
I: Sodium ions
II: Potassium ions
III: Negatively charges proteins present in the axoplasm
| 1. | I and II only | 2. | I and III only |
| 3. | II and III only | 4. | I, II and III |
Subtopic: Â Origin of Resting Membrane Potential |Â Action Potential |
 84%
Level 1: 80%+
Hints
Each time the sodium-potassium pump functions, it actively transports:
| 1. | 3 sodium ions outwards and 2 potassium ions into the cell. |
| 2. | 3 sodium ions into the cells and 2 potassium outwards. |
| 3. | 2 sodium ions outwards and 3 potassium ions into the cell. |
| 4. | 2 sodium ions into the cells and 3 potassium ions outwards. |
Subtopic: Â Origin of Resting Membrane Potential |Â Action Potential |
 87%
Level 1: 80%+
Hints
In a resting axonal membrane:
| 1. | The outer surface possesses a positive charge while its inner surface becomes negatively charged. |
| 2. | The outer surface possesses a negative charge while its inner surface becomes positively charged. |
| 3. | Both the outer and the inner surface are positively charged. |
| 4. | Both the outer and the inner surface are negatively charged. |
Subtopic: Â Origin of Resting Membrane Potential |Â Action Potential |
 91%
Level 1: 80%+
Hints
The electrical potential difference across the resting axonal membrane is called as the:
| 1. Resting potential | 2. Action potential |
| 3. Threshold potential | 4. Reversal potential |
Subtopic: Â Origin of Resting Membrane Potential |Â Action Potential |
 85%
Level 1: 80%+
Hints
Consider the given statements:
1. Only I and II are correct
2. Only I and III are correct
3. Only II and III are correct
4. I, II and III are correct
| I: | When a stimulus is applied at a site on the polarised axonal membrane, the membrane at that site becomes freely permeable to sodium ions. |
| II: | A rapid influx of sodium at this point leads to reversal of polarity and the membrane at the site is said to be depolarised. |
| III: | The electric potential difference at the site is called the action potential which is in fact termed as nerve impulse. |
1. Only I and II are correct
2. Only I and III are correct
3. Only II and III are correct
4. I, II and III are correct
Subtopic: Â Origin of Resting Membrane Potential |Â Action Potential |
 87%
Level 1: 80%+
Hints
The re-establishment of the resting membrane potential after depolarization is primarily due to:
| 1. Sodium potassium pump | 2. Influx of sodium |
| 3. Efflux of potassium | 4. Efflux of sodium |
Subtopic: Â Origin of Resting Membrane Potential |Â Action Potential |
 60%
Level 2: 60%+
Hints
The change in electrical potential that occurs between the inside and outside of a nerve or muscle fiber when it is stimulated, serving to transmit nerve signals is called as:
1. Action potential
2. Threshold potential
3. Reversal potential
4. Excitatory post synaptic potential
Subtopic: Â Origin of Resting Membrane Potential |Â Action Potential |
 88%
Level 1: 80%+
Hints
Consider the two statements:
| I: | Electric synapses are rare in our system. |
| II: | Impulse transmission across electric synapse is always faster than across a chemical synapse. |
1. Both I and II are correct and II explains I
2. Both I and II are correct and II does not explain I
3. Only I is correct
4. Only II is correct
Subtopic: Â Origin of Resting Membrane Potential |Â Action Potential |
 79%
Level 2: 60%+
Hints
- 1(current)
Q. No.
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