Question 57

The cell membrane consists of a phospholipid bilayer.

The structure of the cell membrane is primarily a phospholipid bilayer, which serves as a barrier to protect the cell and regulate the movement of substances in and out of the cell.

A) The cell membrane is composed of nucleic acids.

This statement is incorrect because the primary components of the cell membrane are lipids and proteins, not nucleic acids. Nucleic acids, such as DNA and RNA, are found within the cell’s nucleus and cytoplasm, not in the membrane structure.

B) The cell membrane is impermeable to all substances.

This statement is also incorrect. While the cell membrane selectively controls the passage of certain substances, it is not impermeable. Certain small molecules and nonpolar substances can pass through the membrane, while others require specific transport mechanisms.

C) The cell membrane consists of a phospholipid bilayer.

This statement is correct as it accurately describes the fundamental structure of the cell membrane. The phospholipid bilayer provides a flexible and semi-permeable barrier that is essential for cellular function.

D) The cell membrane is made up of only proteins.

This statement is incorrect because the cell membrane is not solely composed of proteins. While proteins are essential for various functions, they are embedded within the phospholipid bilayer rather than making up the entire structure.

Conclusion

The correct answer, that the cell membrane consists of a phospholipid bilayer, is substantiated by its essential role in forming a barrier while allowing selective permeability for cellular functions. The other options fail to accurately represent the composition and characteristics of the cell membrane, highlighting the importance of understanding its true structure.