Question

complete the following passage. molecules can diffuse across a cell membrane when they move a concentration gradient. in diffusion, very small or uncharged molecules cross the cell membrane. in diffusion, they must rely on the assistance of a to cross. sometimes, energetic input is needed for molecules to move the concentration gradient, a process known as transport. facilitated complex down osmotic active simple against transport protein hydrophilic hydrophobic

Explanation:

Diffusion occurs down a concentration gradient. Simple diffusion involves small or un - charged molecules crossing the membrane freely. Facilitated diffusion requires a transport protein to assist molecule passage. Active transport moves molecules against the concentration gradient with energy input.

Answer:

down; simple; facilitated; transport protein; against; active