Question

Cell membrane or plasma membrane is described as a selectively permeable membrane. Which of the following statements justify the given fact?

• A. Cell membrane allows the entry and exit of some molecules into and out of the cell.
• B. It prevents movement of some other molecules, hence it is called as selectively permeable membrane.
• C. Both A and B.
• D. None of the above

Answer 1

The correct option is C Both A and B.

Cell membrane or plasma membrane is the outer covering of all cells but in plant cells, it is present below the cell wall. It is mainly composed of phospholipid bilayer structure with embedded proteins. The membrane proteins select the molecules and allow them to pass in and out of the cell and thus, makes the membrane selective permeable. It is a thin, delicate, elastic, selectively permeable, protective covering of the cell. It carries out endocytosis, exocytosis and transport of various substances through different carrier proteins. Thus, the correct answer is option C.