How do substances move across cell membranes?
substances are transported across cell membranes via passive, active and bulk transport process.
- passive transport occurs when substances can cross the semipermeable plasma and organelles membranes and move down the concentration gradient without using energy and happen through diffusion, facilitated diffusion and osmosis.
- active transport occurs when substances are transported up their concentration gradient from a lower to a higher concentration. sodium potassium pump is an active transport mechanism that maintains homeostasis to be electrolytes sodium and potassium.