Question

part f (6 of 6)
what prevents the na+ and k+ gradients from dissipating?
na+ and k+ leaks
h+-k+ atpase
na+-k+ atpase

Explanation:

To determine what prevents the \( \text{Na}^+ \) and \( \text{K}^+ \) gradients from dissipating, we analyze each option:

• \( \text{Na}^+ \) and \( \text{K}^+ \) leaks would cause the gradients to dissipate, not prevent it.
• \( \text{H}^+-\text{K}^+ \) ATPase is involved in proton - potassium transport (e.g., in gastric acid secretion) and not related to \( \text{Na}^+-\text{K}^+ \) gradients.
• \( \text{Na}^+-\text{K}^+ \) ATPase (sodium - potassium pump) actively transports \( 3\text{Na}^+ \) out of the cell and \( 2\text{K}^+ \) into the cell against their concentration gradients, using ATP energy. This active transport counteracts the natural tendency of ions to diffuse down their gradients (which would dissipate the gradients) and thus maintains the \( \text{Na}^+ \) and \( \text{K}^+ \) gradients across the cell membrane.

Answer:

C. \( \text{Na}^+-\text{K}^+ \) ATPase (assuming the options are labeled A, B, C with the last option being \( \text{Na}^+-\text{K}^+ \) ATPase)