Question 39

The charged phosphate groups are hydrophilic.

The phospholipid bilayer of a cell membrane consists of glycerol heads, which are hydrophilic due to their charged phosphate groups, and fatty acid tails, which are hydrophobic. This arrangement allows the bilayer to form a stable barrier in an aqueous environment.

A) The fatty acid tails are hydrophilic.

This statement is incorrect because the fatty acid tails are actually hydrophobic, meaning they do not interact favorably with water. Instead, they avoid water, which is essential for the formation of the bilayer structure.

B) The glycerol heads are hydrophobic.

This statement is also incorrect. The glycerol heads contain charged phosphate groups that are hydrophilic, allowing them to interact with the aqueous environment, which is crucial for the bilayer's function.

C) The charged phosphate groups are hydrophobic.

This statement is false. Charged phosphate groups are inherently hydrophilic, allowing them to attract water molecules and interact with the surrounding aqueous environment. This property is essential for the stability and functionality of the membrane.

D) The charged phosphate groups are hydrophilic.

This statement is correct as it accurately describes the nature of the charged phosphate groups in phospholipids. Their hydrophilic properties enable them to face the aqueous environments both inside and outside the cell, facilitating the bilayer's formation.

Conclusion

The correct answer, that the charged phosphate groups are hydrophilic, highlights the fundamental characteristics of the phospholipid bilayer, which is crucial for cell membrane integrity and function. All other options misrepresent the properties of the components of the bilayer, thereby failing to accurately describe the structure and behavior of cell membranes.