What is an example of a substance that moves through the cell membrane?

Question

What is an example of a substance that moves through the cell membrane by diffusion and active uptake?

Answer 1

Dear L.O..

any molecule that is smaller than the pores in the cellular membrane can cross into and out the cell..

essential molecules like water, oxygen, hydrogen ions and some minerals , potasium, sodium........etc.

some of them difuses with the concentration gradient coz they're small (simple diffusion), while other bigger molecules can diffuse opposing the conc. gradient & this consumes energy in the form of ATP.

about very large molecules like some proteins other complicated process es  can take place like engulfment...

you can visit wikipedia.com to have more information.

Hope this help.. :)  

Answer 2

Diffusion: water or other small molecules like oxygen

Active transports: ions like K+ or Na+ (this happens when your neurons fire).