Cells need to bring in molecules to carry out cellular processes. often, this requires moving the molecules across the cell membrane against the concentration gradient. how do these molecules get into the cell?

a. passive transport by diffusion
b. active transport using atp
c. passive transport by osmosis
d. phagocytosis

B. active transport using ATP

Explanation:

In order to move the molecules across the cell membrane against the concentration gradient energy is required. ATP is most abundant energy resource used to start chemical processes in biological systems. There is membrane transport proteins which need ATP for activation. Active transport of molecules can be classified in to two groups. Primary active transport which require energy like ATP. Secondary active transport involves the use of an electrochemical gradient, and does not use energy produced in the cell.

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