Question

because of diffusion, much needed ______ is able to diffuse into cells. carbon dioxide (co2) oxygen (o2)

Explanation:

Cells need oxygen for cellular respiration. Oxygen diffuses from an area of higher concentration (extracellular environment) to an area of lower concentration (inside the cell) through the cell - membrane. Carbon dioxide is a waste product that diffuses out of cells.

Answer:

Oxygen (O2)