Question

Why can oxygen diffuse across another cell

Answer 1

Some molecules, such as carbon dioxide and oxygen, can diffuse across the plasma membrane directly, but others need help to cross its hydrophobic core. ... A concentration gradient exists for these molecules, so they have the potential to diffuse into (or out of) the cell by moving down it.

Answer 2

Explanation:

the basic principle is DIFFUSION.

oxygen moves into and out of the cell due to the difference of concentration

when the conc. of oxygen in the cell is low w.r.t the surrounding oxygen moves in and vice versa.

hope it helps