The membrane phospholipids form bilayer due to

Correct option is A

Correct Answer: A. Its amphipathic nature

• Phospholipids are amphipathic molecules, meaning:

  • They have a hydrophilic (water-attracting) head.

  • And hydrophobic (water-repelling) tails (fatty acid chains).

• In an aqueous environment (like the cell), they self-assemble into a bilayer:

  • Heads face the water (both inside and outside the cell).

  • Tails face inward, away from water, creating a hydrophobic core.

• This structure is the foundation of the cell membrane, giving it selective permeability and fluidity.

• Option B is incorrect: Unsaturated fatty acids are usually in the tail, not the head.

• Option C: While saturated and unsaturated tails affect membrane fluidity, they are not responsible for the bilayer formation.

• Option D: Cholesterol modulates membrane fluidity, but does not cause bilayer formation.

• This amphipathic nature is also key to:

  • Membrane protein insertion

  • Vesicle formation

  • Signal transduction