Q. No.The neuron in humans with many nerve fibers arising from its cell body and that carries impulses to the effectors would be called as:
| 1. | multipolar | 2. | bipolar |
| 3. | unipolar and sensory | 4. | multipolar and motor |
The change in membrane potential that returns it to a negative value just after an action potential has changed the membrane potential to a positive value is called as:
| 1. | depolarization | 2. | hyperpolarization |
| 3. | repolarization | 4. | overshoot |
All the following statements with respect to the propagation of action potentials are correct except:
1. Saltatory conduction occurs in myelinated nerve fibers
2. During conduction of an action potential, current flows from the active area of the membrane to the adjacent inactive area, thereby decreasing the potential in the inactive area to the threshold
3. Action potential propagation is faster in myelinated fibers than in unmyelinated ones
4. Action potential propagation is faster for strong stimuli than for weaker stimuli
What is true for the events that occur during the generation of an action potential?
1. Potassium channels in the membrane open in response to depolarization
2. Sodium channels in the membrane open in response to neurotransmitter released from the adjacent membrane
3. The increase in sodium permeability in the membrane is an example of positive feedback
4. The movement of sodium into the neuron causes the cell to hyperpolarize
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R):
| Assertion (A): | Most of the synapses in vertebrates conduct information in only one direction. |
| Reason (R): | Only the postsynaptic cells can bind and respond to neurotransmitters. |
In the light of the above statements choose the correct answer from the options given below:
| 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. | Both (A) and (R) are false. |
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
| 1. | impermeable to Na+ ions and relatively more permeable to K+ ions. |
| 2. | impermeable to Na+ ions and K+ ions. |
| 3. | freely permeable to Na+ ions and relatively more impermeable to K+ ions. |
| 4. | freely permeable to Na+ ions and K+ ions. |
| Assertion (A): | Electrical synapse are rarer than chemical synapse in human body. |
| Reason (R): | Electrical synapse are faster than the chemical synapse. |
| 1. | Both (A) and (R) are True and (R) correctly explains (A). |
| 2. | (A) is True; (R) is False |
| 3. | (A) is False; (R) is False |
| 4. | Both (A) and (R) are True but (R) does not correctly explain (A). |
| Assertion (A): | Electrical synapses allow for faster transmission than chemical synapses. |
| Reason (R): | Electrical synapses are rare in our system. |
| 1. | Both (A) and (R) are True but (R) does not correctly explain (A). |
| 2. | Both (A) and (R) are True and (R) correctly explains (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
| 1. | Diffusion of sodium to the inside of the cell. |
| 2. | Diffusion of sodium to the outside of the cell. |
| 3. | Diffusion of potassium to the outside of the cell. |
| 4. | Diffusion of potassium to the inside of the cell. |
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