Question

multiple choice question
what is the process whereby an ion, an atom, or a molecule crosses a membrane without using energy?
endocytosis
exocytosis
active transport
passive transport

Explanation:

Endocytosis is the process of taking substances into the cell by forming a vesicle from the cell - membrane, requiring energy. Exocytosis is the process of releasing substances from the cell, also energy - consuming. Active transport moves substances against the concentration gradient and requires energy. Passive transport, such as diffusion and osmosis, moves substances down the concentration gradient without using energy.

Answer:

D. passive transport