Which statement best explains the function of the cell membrane (lipid bilayer) in living cells?

• A. It stores most of the cell’s genetic information and directly controls inheritance.
• B. It acts as a selectively permeable barrier that regulates the movement of substances into and out of the cell and helps maintain homeostasis.
• C. It serves primarily as the site of ribosome assembly and protein synthesis for the cell.
• D. It provides the main structural framework for the cell by forming rigid cellulose microfibrils.

Answer: (B)

Verified step by step guidance

1. Identify the main components and functions of the cell membrane (lipid bilayer). The cell membrane is primarily composed of a phospholipid bilayer with embedded proteins, which creates a flexible and semi-permeable barrier around the cell.
2. Understand the role of the cell membrane in controlling the movement of substances. It selectively allows certain molecules to enter or exit the cell, which is essential for nutrient uptake, waste removal, and communication with the environment.
3. Recognize that the cell membrane helps maintain homeostasis by regulating the internal environment of the cell, keeping conditions stable despite changes outside the cell.
4. Compare the given options with the known functions of the cell membrane: storing genetic information is the role of the nucleus, ribosome assembly occurs in the nucleolus, and cellulose microfibrils are part of the plant cell wall, not the membrane.
5. Conclude that the best explanation for the function of the cell membrane is that it acts as a selectively permeable barrier regulating substance movement and maintaining homeostasis.