Question

Neuron is stimulated, the membrane potential of the plasma membrane shifts to a less negative value by opening voltage-gated K+ channels:
(a) True
(b) False

Answer 1

Answer:

B. False

Explanation:

Resting potential: When a nerve fiber is at rest, it is observed that the outer surface is positively charged and inner surface is negatively charged. This is due to differential distribution of ions (Na+ and K+) and negatively charged protein inside the cell.

Na+ ions are more outside the cell whereas K+ ions are more inside the cell.  The potential difference across the membrane under resting condition was -70 mV and is called resting potential.

When the cell is at rest, both Na+ and K+ voltage gated channels are closed. When a threshold stimulus is applied, the voltage gated Na+ channels open up, allowing Na+  ions to enter the neuron. This causes the neurons interior to develop a positive charge. The membrane is said to be depolarized and the action potential of +30 mV is obtained.  

Answer 2

Answer:

False.

Explanation:

Neuron or nerve cell may be defined as the structural and functional unit of the nervous system. The stimulation of nerve helps in the transmission of messages in the body.

Th resting membrane potential of the plasma membrane is -70mV. The maintenance of negative membrane potential is due to the presence of potassium ions. The influx of potassium ions makes the membrane more negative and influx of sodium ions makes the membrane potential less negative.

Thus, the answer is false.