Question

In the plasma membrane of a few animals, the presence of cholesterol
(a) Makes the membrane less flexible permitting it to sustain greater pressure from within the cell
(b) Enables the membrane to stay fluid more easily when the temperature of the cell drops
(c ) Enables the animal to remove hydrogen atoms from the saturated phospholipids
(d) Enables the animal to add hydrogen atoms to unsaturated phospholipids

Answer 1

Hint:
The fluidity of the lipid bilayer depends on lipid composition. The lipid composition depends on the types of phospholipids and glycolipids, amount of cholesterol, degree of unsaturation of fatty acyl chains, and saturated and unsaturated nature of fatty acyl chains.

Complete step by step answer:
Cholesterol is a major determinant of membrane fluidity. The presence of cholesterol increases order and rigidity. Cholesterol stabilizes the arrangement of saturated fatty acids by van der Waals interactions that are in the straight-chain rearrangement. The presence of cholesterol is a characteristic of the plasma membrane of animal cells rather than plant cells. As a result, animal cell plasma membranes are less fluid than plant cell plasma membranes.

Option ‘B’ is correct

Note:
The fluidity of the lipid bilayer, the optimal value of which is a prerequisite for normal cell growth and function, depends on lipid composition and temperature. In general, an increase in temperature tends to elevate membrane fluidity. When the temperature is lowered it causes less viscosity, fluid membrane structure and not a rigid structure. This change is described as phase transition and the temperature at which this happens is called the transition temperature.