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 diffusionB. active transport using ATPC. passive transport by osmosisD. phagocytosis

B (active transport using ATP)

Explanation:

Movement of substances normally occur in the direction of concentration gradient/difference i. e. the difference in concentration of a substance across a membrane. Letting molecules diffuse or pass down their concentration gradient does not require energy but pumping those molecules against gradient requires energy in form of Adenosine triphosphate (ATP). This process is called Active transport.

In order to perform certain cellular processes, cells need to move substances from their surroundings into the cell across their cell membrane. Moving this substances against the concentration gradient between the cell membrane and its extracellular fluid requires energy (ATP).

An example is the sodium-pottasium pump employed by animal cells in which they expend energy to move K + molecules into the cell and Na + molecules outside the cell against the concentration gradient of their cell membrane and extracellular solution.