Some cellinlar processes require building a high concentration of molecules on one side of the cell membrane.What method would a cell use to move molecules to an area where the molecules are already highly concentrated? passive transport osmosis diffusion active transport

## Step 1<br />The question is asking about the method a cell would use to move molecules to an area where the molecules are already highly concentrated. This is a process that requires energy because it is moving molecules against their concentration gradient, which is from an area of lower concentration to an area of higher concentration.<br /><br />## Step 2<br />The process that fits this description is active transport. Active transport is a process that uses energy to move molecules against their concentration gradient. This is different from passive transport, osmosis, and diffusion, which all move molecules from areas of higher concentration to areas of lower concentration, or along their concentration gradient.