Question

Which of the following statements about the plasma membrane is true?

• A. It is a solid layer of protein that protects the contents of the cell.
• B. The plasma membrane of a bacterium has none of the same components as the plasma membrane of an animal cell.
• C. It is a rigid and unmoving layer of phospholipids and proteins.
• D. It allows selected molecules to pass into and out of the cell.

Answer 1

The correct option is D

It allows selected molecules to pass into and out of the cell.

The correct option is D

Explanation of the correct option:

1. The plasma membrane or cell membrane is the outermost layer in the animal cell and the second outermost layer in the plant cell.
2. A plasma membrane is mainly composed of carbohydrates, phospholipids, and proteins, which are about 5 to 8 nm in thickness.
3. The plasma membrane is a flexible lipid bilayer that surrounds and contains the cytoplasm of the cell.
4. Functions as a physical barrier between the external environment and the inner cell environment.
5. It is a selectively permeable membrane, which permits the movement of only certain molecules both in and out of the cell.
6. Helps in the endocytosis and exocytosis process.
7. Functions by facilitating the communication and signaling between the cells.
8. Provides shape to the cell and also maintains the cell potential.

Final answer: Plasma membrane allows selected molecules to pass into and out of the cell.