The correct statement about the cell membrane is option 3: It is flexible and enables the cell to engulf many materials.

Let`s dissect each option to understand them better:

Option 1: It is made up of cellulose. This statement is incorrect. The cell membrane is primarily composed of lipids and proteins, not cellulose. Cellulose is a carbohydrate found in the cell wall of plant cells, not in the cell membrane.

Option 2: It is a permeable structure for all substances. This statement is incorrect. The cell membrane is selectively permeable, meaning it allows certain substances to pass through while restricting others. It controls the movement of ions, molecules, and substances in and out of the cell.

Option 3: It is flexible and enables the cell to engulf many materials. This statement is correct. The cell membrane is a flexible structure that can change shape and allow the cell to engulf materials through a process called endocytosis. It also plays a role in cell movement and communication.

Option 4: It does not allow diffusion of gases like oxygen and carbon dioxide. This statement is incorrect. The cell membrane allows for the diffusion of gases, including oxygen and carbon dioxide, which are small molecules that can pass through the lipid bilayer.

In