2. Transport across cell membranes

Question 1

Answer 1

Question 2

Movement across membrands occurs by:

Answer 2

Movement across membrands occurs by:

• simple diffusion (involving limitations imposed by the nature of the phospholipid bilayer)
• facilitated diffusion (involving the roles of carrier proteins and channel proteins) osmosis (explained in terms of water potential)
• active transport (involving the role of carrier proteins and the importance of the hydrolysis of ATP)
• co-transport (illustrated by the absorption of sodium ions and glucose by cells lining the mammalian ileum).