In some cells, there are many different ion electrochemical gradients across the plasma membrane even though there are usually only one or two types of proton pumps present in the membrane. The gradients of the other ions are most likely established by which of the following?
A) cotransport proteins
B) ion channels
C) pores in the plasma membrane
D) passive diffusion across the plasma membrane

Question

Quizplus · Accepted Answer

Cotransport proteins can establish gradients of various ions across the plasma membrane by using the energy stored in the gradient of one ion (often protons or sodium ions) to move another ion against its gradient. This mechanism allows for the establishment of electrochemical gradients for ions other than those directly pumped by proton pumps or other primary active transport mechanisms.

In Some Cells, There Are Many Different Ion Electrochemical Gradients