Which statement about the cell membrane is true?

Which statement about the cell membrane is true?

• A. It is a rigid barrier impermeable to all substances
• B. It is a phospholipid bilayer with embedded proteins
• C. It stores genetic material
• D. It conducts photosynthesis

Answer: (D)

The cell membrane is best described as a phospholipid bilayer with embedded proteins. The phospholipid arrangement creates a flexible, semi-permeable barrier: hydrophilic heads face the watery outside and inside of the cell, while hydrophobic tails tuck away in the interior, allowing the membrane to act as a selective gatekeeper. Proteins scattered within this bilayer enable transport of ions and polar molecules, facilitate signaling, and support cellular structure, making the membrane a dynamic, fluid mosaic rather than a rigid barrier. This setup explains why some substances cross easily while others require specific channels or carriers. The membrane doesn’t store genetic material—genetic material is housed in the nucleus or the cytoplasm's nucleoid in prokaryotes—and photosynthesis is carried out in chloroplasts, not the membrane itself.

The cell membrane is best described as a phospholipid bilayer with embedded proteins. The phospholipid arrangement creates a flexible, semi-permeable barrier: hydrophilic heads face the watery outside and inside of the cell, while hydrophobic tails tuck away in the interior, allowing the membrane to act as a selective gatekeeper. Proteins scattered within this bilayer enable transport of ions and polar molecules, facilitate signaling, and support cellular structure, making the membrane a dynamic, fluid mosaic rather than a rigid barrier. This setup explains why some substances cross easily while others require specific channels or carriers. The membrane doesn’t store genetic material—genetic material is housed in the nucleus or the cytoplasm's nucleoid in prokaryotes—and photosynthesis is carried out in chloroplasts, not the membrane itself.