Question 23

The head of a phospholipid is both hydrophilic and faces the outer side of the layer.

In a phospholipid, the head is hydrophilic, meaning it has an affinity for water, and it is oriented towards the aqueous environment, facing the outer side of the lipid bilayer.

A) Is hydrophilic

This option is correct as the head of a phospholipid is indeed hydrophilic. The polar nature of the head allows it to interact favorably with water molecules, which is essential for the formation of cellular membranes.

B) Is hydrophobic

This option is incorrect because the head of a phospholipid is not hydrophobic. Instead, it is the tail region that is hydrophobic, repelling water and contributing to the overall structure of the lipid bilayer.

C) Faces the outer side of the layer

This option is correct as the heads of phospholipids do face the outer side of the lipid bilayer, allowing them to interact with the surrounding aqueous environment.

D) Both A and C

This option is correct because it encompasses both the hydrophilic nature of the head (A) and its orientation towards the outer side of the layer (C). Thus, D accurately reflects the properties of phospholipid heads.

Conclusion

The correct answer is D, as it combines the essential characteristics of phospholipid heads, which are hydrophilic and oriented outward. Options A and C are individually correct but do not capture the complete picture as effectively as D does. Options B and any other non-included options do not reflect the accurate properties of phospholipids.