A student has placed rabbit cells in a solution containing dissolved oxygen, glucose, calcium ions, water, and sodium ions. Which of these molecules do you expect will easily enter into the student's rabbit cells (via simple diffusion) ?

A. calcium ions

B. glucose

C. sodium ions

D. oxygen

E. water

The correct answer is D. oxygen

Explanation:

The plasma membrane is selectively permeable which means it allows the selective molecule to pass through it. The charged molecule is passed mainly through active transport.

Water molecules pass through a type of passive diffusion called osmosis. Gases like oxygen and carbon dioxide move through simple diffusion. When oxygen moves in the cell carbon dioxide moves out of the cell. In diffusion, the molecule moves down their concentration gradient so no energy is needed in it. So the correct answer is D.