The cell membrane is mainly composed of proteins and carbohydrates.

• True

• False

The structure of the cell membrane is ‘fluid’ in nature because the phospholipid molecules can move laterally.

• True

• False

The ‘head’ of a phospholipid molecule is hydrophobic.

• True

• False

____________ are membrane proteins which contain carbohydrates attached to their surface. These proteins can act as recognition markers.

• Carrier proteins

• Receptor proteins

• Enzymes

• Glycoproteins

The cell membrane is differentially permeable. It is permeable to (a)____________ substances but impermeable to (b)____________ substances.

• (a) lipid-soluble；(b) water-soluble

• (a) water-soluble；(b) lipid-soluble

Glucose and amino acids move across the cell membrane through channel proteins or ____________ .

• carrier proteins

• receptor proteins

• enzymes

• glycoproteins