Action Potential

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

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

Q.

Explain the following processes :

(a) Polarization of the membrane of a nerve fibre.

(b) Depolarization 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. When a stimulus is applied at a site on the polarised membrane:

1. $N{a}^{+}$ moves out of axoplasm
2. $C{a}^{2+}$ moves into axoplasm
3. $K^{+}$ moves into axoplasm
4. $N{a}^{+}$ moves into axoplasm

Q. Enzymes are catalysts. They catalyze biochemical reactions. In general, they reduce the activation energy of reactions. Many physico-chemical processes are enzyme mediated. Which of the following reactions is not enzyme-mediated in the biological system?

1. Hydrolysis of sucrose
2. Dissolving $C{O}_2$ in water
3. Untwining the two strands of DNA
4. Formation of peptide bond

Q. Which of these ions are present in higher concentration in the extracellular fluid (ECF), relative to the intracellular fluid (ICF)?

1. Cations
2. (K⁺) ions
3. Anions
4. (Na⁺) 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. (iii), (iv) and (v)
3. (i), (ii) and (iii)
4. All except (v)

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.

Paheli accidentally placed her hand over a flame and immediately pulled it back. She felt the sensation of heat and reacted due to the action of

1. Blood cells

2. Skin surface

3. Nerve cells

4. Nucleus of cells

Q. Permeability of which of the following increases during depolarization?

1. $N{a}^{+}$
2. Both $N{a}^{+}$ and $K^{+}$
3. $K^{+}$
4. None of the above

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

1. At resting phase, the axonal membrane is comparatively more permeable to potassium ions $\left(K^{+}\right)$ and nearly impermeable to sodium ions $\left(N{a}^{+}\right)$
2. The electrical potential difference across the resting plasma membrane is called the action potential
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.

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.

The diffusion of potassium ions out of a neuron after depolarisation causes : _____.

1. Repolarization

2. Action potential

3. Nerve impulse

4. Depolarization

Q. Match the column I and column II and choose the correct option.
$\begin{array}{cc}\text{Column I}& \text{Column II}\\ \text{A.Synapse}& \text{I. Opening of sodium channels}\\ & \text{resulting in rapid influx of sodium}\\ & \text{and closing of sodium channels.}\\ \text{B.Repolarization phase}& \text{II. The electrical potential difference}\\ & \text{across the resting plasma membrane.}\\ \text{C. Resting Potential}& \text{III. The site of transmission of electric}\\ & \text{nerve impulses between two neurons.}\\ \text{D. Depolarization}& \text{IV. Opening of potassium channels}\\ & \text{and rushing out of potassium.}\end{array}$

1. A-II, B-I, C- IV, D-III
2. A-III, B- I, C- II, D- IV
3. A-IV, B-II, C-I, D-III
4. A-III, B-IV, C-II, D-I

Q. Which ions are necessary for transmission of action potential through synapse?

1. Potassium and Calcium
2. Sodium and Calcium
3. Chloride and Sodium
4. Potassium and Sodium

Q.

An action potential traveling along an axon

1. moves rapidly in both directions.

2. moves faster than a neurotransmitter

3. is slowed by myelin.

4. travels through the blood.

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. C
2. B
3. A
4. D

Q. Lactose metabolising enzyme, produced in the presence of lactose only is

1. Inducible enzyme
2. Constitutive enzyme
3. Repressible enzyme
4. Regulatory enzyme

Q.

An action potential is _____.

1. Outflux of negative ions to depolarize the membrane

2. Initiated by potassium ion movements

3. Outflux of positive ions to depolarize the membrane

4. Essential for nerve impulse propagation

Q. Which of these ions are present in higher concentration in the extracellular fluid (ECF), relative to the intracellular fluid (ICF)?

1. Cations
2. (K⁺) ions
3. Anions
4. (Na⁺) ions

Q. Match the column I and column II and choose the correct option.
$\begin{array}{cc}\text{Column I}& \text{Column II}\\ \text{A.Synapse}& \text{I. Opening of sodium channels}\\ & \text{resulting in rapid influx of sodium}\\ & \text{and closing of sodium channels.}\\ \text{B.Repolarization phase}& \text{II. The electrical potential difference}\\ & \text{across the resting plasma membrane.}\\ \text{C. Resting Potential}& \text{III. The site of transmission of electric}\\ & \text{nerve impulses between two neurons.}\\ \text{D. Depolarization}& \text{IV. Opening of potassium channels}\\ & \text{and rushing out of potassium.}\end{array}$

1. A-II, B-I, C- IV, D-III
2. A-III, B- I, C- II, D- IV
3. A-III, B-IV, C-II, D-I
4. A-IV, B-II, C-I, D-III

Q. Which of the following is incorrect for generation and conduction of nerve impulse?

1. Ionic gradients across the resting membrane are maintained by the active transport of ions by the sodium-potassium pump
2. When a stimulus is applied at a site on the polarised membrane, the membrane at the site becomes freely permeable to Na+
3. The rise in the stimulus-induced permeability to Na+ is extremely shortlived which is quickly followed by a rise in permeability to K+.
4. During conduction of impulse, the axon membrane has a negative charge on the outer surface and positive charge on its inner surface

Q. Explain about ionization enthalpy ? Why IE2>IE1?

Q.

At the membrane potential when voltage gated Na⁺ channels open, an action potential is sure to fire. This membrane potential is called _____.

1. Depolarising potential

2. Threshold potential

3. Resting potential

4. Action potential

Q.

Action potential in a polarised neuron triggers _____.

1. Depolarization

2. Hyperpolarization

3. Repolarization

4. No change

Q.

Which of the following statement characterizes the depolarized state of a neuron?

1. $K^{+}$ outflow begins

2. $K^{+}$ channels remain open

3. $N{a}^{+}$ gets outside through channels

4. $N{a}^{+}$ gets inside through ion channels

Q.

Which of the following statement characterizes the depolarized state of a neuron?

1. $K^{+}$ outflow begins

2. $K^{+}$ channels remain open

3. $N{a}^{+}$ gets outside through channels

4. $N{a}^{+}$ gets inside through ion channels

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

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

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. $N{a}_{-}^{+}{K}^{+}$ 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