Question

which part of the bilayer is hydrophilic?
a the polar heads
b the nonpolar fatty acid tails
c the carbohydrate chains
d the protein channels
question 4
which part of the bilayer is hydrophobic?
a the nonpolar fatty acid tails
b the carbohydrate chains
c the polar heads
d the protein channels

Explanation:

• Phospholipid bilayers have polar heads and non - polar fatty acid tails.
• Hydrophilic means water - loving. Polar molecules interact well with water (hydrophilic).
• The polar heads of phospholipids are hydrophilic.
• Non - polar fatty acid tails are hydrophobic (water - fearing).
• Carbohydrate chains are attached to the outer surface of the membrane (usually more on the extracellular side) and can be involved in cell - cell recognition etc., but they are not the main hydrophilic part of the bilayer.
• Protein channels can have hydrophilic regions (especially those that interact with the aqueous environment inside and outside the cell), but the question is about the bilayer itself. The bilayer is mainly composed of phospholipids.

Answer:

For the first question (hydrophilic part): A. The polar heads
For the second question (hydrophobic part): A. The nonpolar fatty acid tails