Question

Of the gradients listed below, which is the MOST accurate description of the force that ultimately determines the movement of ions across the membrane?

A) electrochemical gradient

B) potential gradient

C) chemical gradient

D) electrical gradient

E) concentration gradient

Answer 1

The movement of ions across a cell membrane is best described by the electrochemical gradient, which is the combination of chemical (concentration) and electrical (membrane potential) forces driving the ions.

Step-by-step explanation:

The movement of ions across a cell membrane is determined by the electrochemical gradient. This gradient is a combination of the chemical force (concentration gradient of the ions) and the electrical force (membrane potential affecting ion movement). In living cells, particularly muscle and nerve cells, the inside is electrically negative compared to the outside, and the cells have different concentrations of ions like potassium (K+) and sodium (Na+) compared to extracellular fluid. These differences create an electrochemical gradient that drives the ions in or out of the cell based on both concentration differences and electrical charge, with the electrochemical gradient being most accurately described in option A).