Answer:
Concentration and Diffusion
Electrochemical and kinetic energy both power diffusion. The primary determinant of whether a molecule will diffuse across a cell membrane is the concentration of the molecule on each side of the cell membrane. Primary active transport moves ions across a membrane and creates a difference in charge across that membrane. The primary active transport system uses ATP to move a substance, such as an ion, into the cell, and often at the same time, a second substance is moved out of the cell.
To move substances against a concentration or electrochemical gradient, a cell must use energy. Active transport mechanisms do just this, expending energy (often in the form of ATP) to maintain the right concentrations of ions and molecules in living cells.
Explanation:
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