Question

the concentration of sodium on the inside of the cell is 20 mm. the outside of the cell has a sodium concentration of 115 mm. which mechanism of ion uptake would best move sodium from the inside of the cell to the outside? osmosis diffusion passive transport active transport

Explanation:

Osmosis is the movement of water, not ions. Diffusion moves substances from high - to low - concentration areas, but here sodium needs to move from low (20 mM inside) to high (115 mM outside) concentration. Passive transport generally moves substances down their concentration gradient. Active transport can move substances against their concentration gradient, which is required to move sodium from the inside (low concentration) to the outside (high concentration) of the cell.

Answer:

A. active transport