Question

An electrochemical gradient has a chemical component and voltage component. Which of the following will have the largest electrochemical gradient?

A. A positively charged ion present in high concentrations inside the cell.
B. A positively charged ion present in high concentrations outside the cell.
C. A negatively charged ion present in high concentrations inside the cell.
D. A negatively charged ion present in high concentrations outside the cell.

Answer 1

The largest electrochemical gradient will be for a positively charged ion in high concentrations outside the cell, due to both concentration and electrical gradients driving it into the negatively charged cell interior.

Step-by-step explanation:

An electrochemical gradient is comprised of two components: a concentration gradient and an electrical gradient. The concentration gradient refers to the difference in the concentration of ions across a membrane, while the electrical gradient arises from the separation of charges across that membrane.

In this case, a positively charged ion in high concentrations outside the cell will have the largest electrochemical gradient because it will be affected by both the chemical drive to move down its concentration gradient into the less concentrated area inside the cell and the electrical drive to move into the negatively charged interior of the cell. Thus, the answer to the question is B: A positively charged ion present in high concentrations outside the cell will have the largest electrochemical gradient.