Question

Membranes in living cells, including those in humans, are characterized by a separation of charge across the membrane. Effectively, the membranes are thus charged capacitors with important functions related to the potential difference across the membrane. Is energy required to separate these charges in living membranes, and, if so, is its source the metabolization of food energy or some other source?

a) Energy is required, and its source is the metabolization of food energy.

b) Energy is not required; charges separate spontaneously.

c) Energy is required, and its source is some other process.

d) No energy is required; charges separate due to external factors.

Answer 1

Energy is required to separate charges across cell membranes, and this energy comes from the metabolization of food energy, especially through the active transport mechanisms like the sodium-potassium pump.

Step-by-step explanation:

The question regards the energetic requirements of charge separation across cell membranes, which act as charged capacitors with a potential difference across them. The separation of charge is crucial for the function of cells, particularly in the creation and maintenance of a membrane potential, and is integral to the physiology of nerve and muscle cells.

Energy is indeed required to maintain this separation, and it is primarily derived from the metabolization of food energy. Cell membranes use active transport mechanisms, such as the sodium-potassium pump, which utilizes ATP as an energy source—formed from the breakdown of glucose and other nutrients—to move ions against their concentration gradients and establish the resting membrane potential.