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:

Ion movement against a concentration gradient (from low - 20 mM inside to high - 115 mM outside) requires energy. Active transport is the mechanism that uses energy (such as ATP) to move substances against their concentration gradient. Passive transport (diffusion and osmosis) moves substances down their concentration gradient without energy input.

Answer:

active transport