Question

In contact with water, phospholipids produce
(A) Monolayer
(B) Bilayer
(C) Trilayer
(D) Emulsion

Answer 1

Hint: Phospholipids are the type of the lipids with one head and two tails parts. It has both the hydrophilic and hydrophobic areas in its body. The phosphate group is hydrophilic and the fatty acid group is hydrophobic in nature.

Complete Answer:
- In the phospholipid molecule, the phosphate is present at the one end called by the name head. And the two chains of fatty acid form the part of the tail ends. The phosphate at the head end is negatively charged and hence it is water lovable in nature.
- The tail end has the fatty acid which is a neutral charge that repels the water molecule. The head areas of the phospholipids are hydrophilic in nature. The hydrophilic compounds have the greater affinity to the water. And the tail areas of these lipids are hydrophobic in nature.
- The hydrophobic molecules are sensitive to water molecules. When the phospholipid is made in contact with the water, both the hydrophilic and the hydrophobic areas show different characteristics. The hydrophilic areas try to attract the water to its surface and the hydrophobic areas try to remove water from its surface.
- Since the phospholipid molecules exhibit two different characteristics by its own, it forms the lipid bilayer. This lipid spontaneously rearranges itself when they make contact with each other. Hence in contact with water, phospholipids produce bilayer.

Thus, the option (B) is correct.

Note: The bilayer formed by the reaction with the water consists of the two folds of phospholipids which are arranged tail to tail direction. The lipid bilayer serves as the semipermeable membrane in which only the lipophilic compounds can pass through.