Question

Cell membranes are made up of
A. Carbohydrates
B. Phospholipids
C. Cellulose
D. lignin

Answer 1

Cell membrane is the outer covering of the cell which allows transport of molecules to and from the cell. It is a bilayer and is found both in plant and animal cell. It is selectively permeable in nature.

Complete Answer:
- The cell membrane is the outermost protective layering of the cell. It helps in maintaining the steady shape of the cell. It is selectively permeable in nature which allows movement of ions and molecules to and from the cell.
- It is mainly composed of phospholipids bilayer. Phospholipid is made up of glycerol, two fatty acid tails which is hydrophobic and a phosphate head which is hydrophilic. Phospholipids line up and arrange to form two parallel layers. The cell membrane is also made up of proteins and certain oligosaccharides. The proteins act as transporters. It carries molecules to and from the cell.
- Cellulose: The cell wall of a plant cell is made up of cellulose.
- Lignin: It is also found in the cell wall.
- Carbohydrates: It forms a structure called glycocalyx which acts like a coat around the cell.

The correct answer is (B). Cell membranes are made up of phospholipids.

Note: Phospholipids have important structural and functional roles in the cell. The bilayer acts as a barrier for the molecules moving in and out of the cell membrane. It also protects the cell against the external particles.