Question

question 13
if the middle of the phospholipid bilayer is hydrophobic, how does water get through the membrane?
o a water never enters or exits a cell. a cells internal water must never mix with a cells external water
b water is pumped into or out of cell using large amounts of energy
o c water must cross through channels called aquaporins
d water can cross freely anywhere because water molecules are small

Explanation:

• Option a is incorrect because water does enter and exit cells.
• Option b is incorrect as water transport through aquaporins does not require large amounts of energy like active transport (which is what "pumped" implies in a wrong - context here).
• Option c is correct. Aquaporins are channel proteins that allow water to pass through the hydrophobic phospholipid bilayer.
• Option d is incorrect. Although water molecules are small, the hydrophobic interior of the phospholipid bilayer would still prevent free - movement of water without specific channels (aquaporins).

Answer:

C. Water must cross through channels called Aquaporins.