Which property best describes the cell membrane's role?

• A. Stores genetic information
• B. Provides energy
• C. Offers structural support
• D. Controls what enters and leaves the cell

Answer: (D)

The main idea here is that the cell membrane acts as a gatekeeper for the cell. It’s a phospholipid bilayer with proteins that form channels and pumps, making the membrane selectively permeable. This means it carefully controls which substances can enter or leave, allowing nutrients in, removing wastes, and keeping harmful materials out. By doing so, it helps maintain the cell’s internal conditions and energy balance.

Storing genetic information is the job of DNA inside the nucleus, not the membrane. Providing energy comes from organelles like mitochondria, and structural support comes from the cytoskeleton or cell wall.