Action Potential

Q.

What is saltatory conduction?

Q.

What is difference between depolarization and repolarization?

Q.

During the transmission of nerve impulse through a nerve fibre, the potential on the inner side of the plasma membrane has ____ type of electric change.

1. First positive, then negative and continue to be negative

2. First negative, then positive and continue to be positive

3. First positive, then negative and again back to positive

4. First negative, then positive and again back to negative

Q.

During the propagation of a nerve impulse, the action potential results from the movement of ______.

1. K⁺ ion from extracellular fluid to intracellular fluid

2. K⁺ ions from intracellular fluid to extracellular fluid

3. Na⁺ ions from extracellular fluid to intracellular fluid

4. Na⁺ ions from intracellular fluid to extracellular fluid

Q. The depolarization of the axonal membrane is due to:

1. Influx of sodium ions
2. Efflux of sodium ions
3. Influx of potassium ions
4. Efflux of the potassium ions

Q.

An action potential is caused by an influx of _____ ions into the cell.

1. Sodium

2. Both Potassium and Sodium

3. Potassium

4. Calcium

Q.

One of the following is an active process?

1. Cytochrome-Pump theory

2. Carrier ion exchange concept

3. Both b & c are correct

4. Ion exchange

Q. An action potential in the nerve fibre is produced when positive and negative charges on outside and the inside of the axon membrane are reversed because

1. More potassium ions enter the axon as compared to sodium ions leaving it
2. More sodium ions enter the axon as compared to potassium ions leaving it
3. All potassium ions leave the axon
4. All sodium ions enter the axon

Q. Which of the following is correct about generation and conduction of nerve impulse?

1. The electrical potential difference across the resting plasma membrane is called the action potential
2. At resting phase, the axonal membrane is comparatively more permeable to potassium ions $\left(K^{+}\right)$ and nearly impermeable to sodium ions $\left(N{a}^{+}\right)$
3. The ionic gradients across the resting membrane are maintained by the active transport of ions by the sodium-potassium pump which transports $2N{a}^{+}$ outwards for $3K^{+}$ into the cell
4. Depolarization is due to rapid influx of potassium ions

Q. Which of the following statements are correct?
(i) Chitin, a complex or heteropolysaccharide occuring in the exoskeleton consists of NAG.
(ii) Glucosamine and N-acetyl glucosamine (NAG) are modified sugars.
(iii) Cellulose shows blue colour when treated with Iodine.
(iv) Starch in plants and glycogen in animals are store houses of energy.
(v) Right end of polysaccharide is called the reducing end while the left end is called non-reducing end.

1. All except (iii)
2. All except (v)
3. (i), (ii) and (iii)
4. (iii), (iv) and (v)

Q.

Explain the following processes:

(a) Polarisation of the membrane of a nerve fibre

(b) Depolarisation of the membrane of a nerve fibre

(c) Conduction of a nerve impulse along a nerve fibre

(d) Transmission of a nerve impulse across a chemical synapse

Q.

Fill in the correct sequence for generation of Action potential in a neuron

Stimulus ⟶Inflow of Na+ ions ⟶ ______⟶Repolarisation ⟶_________

1. Transmission of Na+ & K+ Hyperpolarization & RMP

2. Transmission of Na+ Inflow of Na+ ions

3. Inflow of Na+ ions Transmission of Na+

4. Hyperpolarization Inflow of Na+ ions

Q.

Action potential in a polarised neuron triggers -

1. Depolarisation

2. Repolarisation

3. No change

4. Hyperpolarization

Q. In unmyelinated neurons, voltage gated channels are present at regular intervals to ensure that is regenerated at regular intervals.

1. action potential
2. electricity
3. ATP

Q. An action potential is sure to fire, once ___ channels are open.

1. Volatge gated Na+
2. Voltage gated K+
3. K+ leak channels
4. Ligand gated Na+

Q. $N{a}_{-}^{+}{K}^{+}$ pumps are found in membranes of many cells, like nerve cells. It works against electrochemical gradient and involves an integral protein ATPase. For each molecule of ATP used

1. 3 ions of $N{a}^{+}$ are pumped out and $2K^{+}$ are taken in
2. 3 ions of $N{a}^{+}$ are taken in and $2K^{+}$ are pumped out
3. 2 ions of $N{a}^{+}$ are thrown out and $3K^{+}$ are absorbed
4. 3 ions of $K^{+}$ are absorbed, $3N{a}^{+}$ are pumped out

Q. Match the following stages of action potential to its corresponding state of ion movement

I. Depolarization stage (p). (K⁺) ions move outside the cell
II. Repolarization stage (q). (Na⁺) ions move inside the cell
III. Hyperpolarization stage (r). No net ion movement
IV. Resting stage (s). (K⁺) ions move into the cell
V. Threshold potential (t). Ligand gated sodium channels open
VI. Stimulus reaches the neuron (u). Voltage gated sodium channels open

1. I. (p), II. (u), III. (q), IV. (r), V. (s), VI. (t)
2. I. (q), II. (p), III. (s), IV. (r), V. (u), VI. (t)
3. I. (s), II. (p), III. (p), IV. (t), V. (u), VI. (r)
4. I. (p), II. (s), III. (r), IV. (u), V. (t), VI. (q)

Q. Ions diffuse freely along their (i)___, from the region of (ii)___ concentration and (iii)___ charge to the region of (iv)___ concentration and (v)___charge.

1. (i) concentration gradient, (ii) high, (iii) opposite, (iv) low, (v) similar
2. (i) electrochemical gradient, (ii) high, (iii) opposite, (iv) low, (v) similar
3. (i) concentration gradient, (ii) high, (iii) similar, (iv) low, (v) opposite
4. (i) electrochemical gradient, (ii) high, (iii) similar, (iv) low, (v) opposite

Q.

The propagation of a nerve impulse is due to changes in the permeability of the nerve cell membrane that allows for a voltage difference across the membrane.

1. True
2. False

Q. Which of the following is correct about generation and conduction of nerve impulse?

1. The ionic gradients across the resting membrane are maintained by the active transport of ions by the sodium-potassium pump which transports $2N{a}^{+}$ outwards for $3K^{+}$ into the cell
2. The electrical potential difference across the resting plasma membrane is called the action potential
3. Depolarization is due to rapid influx of potassium ions
4. At resting phase, the axonal membrane is comparatively more permeable to potassium ions $\left(K^{+}\right)$ and nearly impermeable to sodium ions $\left(N{a}^{+}\right)$

Q. Refer the figure to answer the question. Identify the region where all $N{a}^{+}$ channels are reactivated, but closed and all $K^{+}$ channels are closed.

1. D
2. C
3. B
4. A

Q. Action potential results from the movement of

1. ${\mathrm{Na}}^{+}$ from intracellular fluid to extracellular fluid
   
2. ${\mathrm{Na}}^{+}$ from extracellular fluid to intracellular fluid
3. ${\mathrm{Na}}^{+}$ in both directions
4. Stagnation of ${\mathrm{Na}}^{+}$ ions