Biology Question Papers for NEET Exam on “Neuron-2”.
1. At resting membrane potential, the axonal membrane is impermeable to which ions?
a) Calcium ions
b) Sodium ions
c) Potassium ions
d) Chlorine ions
Answer: b
Clarification: The axonal membrane of the neuron or nerve cell is semi-permeable in nature. At resting membrane potential, the membrane is permeable to potassium ions but nearly impermeable to sodium ions.
2. Which of the following is not true regarding resting potential?
a) There is a potential difference across the plasma membrane
b) The potential difference is maintained by the Na-K pump
c) The outer surface of the membrane is negatively charged
d) The axonal membrane is polarized
Answer: c
Clarification: The axonal membrane is positively charged on the outer surface and negatively charged on the inner surface. This makes the membrane polarized. The potential difference is maintained by the Na-K pump.
3. Which of these does not take place when a stimulus is applied to a polarized axonal membrane?
a) It becomes permeable to sodium ions
b) The membrane is depolarized
c) There is a slow influx of sodium ions
d) Outer surface of the membrane becomes negatively charged
Answer: c
Clarification: When a stimulus is applied to a polarized axonal membrane, the polarity of the membrane is reversed. It becomes permeable to sodium ions and leads to its rapid influx. Outer surface of the membrane becomes negatively charged.
4. What is a nerve impulse also known as?
a) Action potential
b) Graded potential
c) Resting potential
d) Membrane potential
Answer: a
Clarification: A nerve impulse is also known as an action potential. It changes the resting membrane potential as it reverses the polarity of the axonal membrane. It becomes permeable to sodium ions and leads to its rapid influx.
5. How is the resting potential restored after a nerve impulse?
a) Potassium ions diffuse inside the membrane
b) Potassium ions diffuse outside the membrane
c) The membrane becomes impermeable to potassium ions
d) There is no movement of potassium ions
Answer: b
Clarification: After a nerve impulse, the permeability of the membrane to sodium ions reduces and increases for potassium ions. Potassium ions diffuse outside the membrane and hence restore the resting potential.
6. Nerve impulses are transmitted from one neuron to another via which of these?
a) Schwan cells
b) Nissl’s granules
c) Synapses
d) Myelin sheath
Answer: c
Clarification: Synapses are the gaps or junctions between two adjacent neurons via which nerve impulses are transmitted. This occurs by the release of chemical compounds known as neurotransmitters.
7. Which of these is not a component of the synapse?
a) Synaptic vesicles
b) Pre-synaptic membrane
c) Post-synaptic membrane
d) Synaptic cleft
Answer: a
Clarification: A synapse is present between two adjacent neurons. The pre-synaptic membrane of one neuron, the post-synaptic membrane of the next neuron and the synaptic cleft make up the synapse.
8. Which of the following statements is false regarding electrical synapses?
a) Membranes of pre and post-synaptic neurons are in very close proximity
b) Transmission is always faster than that across a chemical synapse
c) It is similar to impulse conduction along a single axon
d) Electrical synapses are common in our system