Question

Ion X+ is sitting outside of a cell. Which of the following scenarios will cause ion X+ to move into a cell?

A) High concentration of a negative ions inside the cell, and low concentration of X+ inside the cell.

B) Low concentration of negative ions inside the cell, and high concentration of X+ inside the cell.

C) Low concentration of positive ions outside the cell, high concentration of X+ outside the cell.

D) High concentration of negative ions outside the cell, low concentration of X+ inside the cell.

Someone said it was B, I thought it was A.

Their logic was it's B because it's active transport not passive, why?

Answer 1

A) High concentration of a negative ions inside the cell, and low concentration of X+ inside the cell.

Explanation: High concentration of negative charge inside the cell compared to outside creates the electrical gradient across the cell that allows the movement of negative to move out or positive charge to move inside the cell to maintain electrical equilibrium. This Electrical gradient will allow positive charge X+ ion to move inside the cell.

Also, Low concentration of X+ inside the cell compared to outside creates a concentration gradient directing inwards. This concentration will also allow the X+ ions to move inside the cell.