temperature and membrane composition?

Question

which of the following responses are not likely to be seen when a bacterial culture growing at 37'C is transferred to a culture room maintained at 25'C?Explain your reasoning.
a.Initial decrease in membrane fluidity
b.Gradual replacement of shorter fatty acids by longer fatty acids in the membrane phospholipids
c.Gradual replacement of stearate by oleate in the membrane phospholipids
d.Enhanced rate of synthesis of unsatured fatty acids
e.Incorporation of more cholesterol into the membrane

Answer 1

When the temperature is decreased, the membrane will initially be more solid, less fluid, so A is correct.

The bacterium will adapt to the decreased fluidity of its membrane by making the membrane more fluid again. That can occur by replacing saturated fatty acids with unsaturated ones, and by replacing longer fatty acids by shorter ones.

So, both C and D are correct.

B is wrong, since that would make the membrane LESS fluid, not more fluid. E is incorrect since prokaryotic organisms do not have cholesterol in their membranes.

Answer 2

E. is incorrect. Increasing cholestrol in the membrane will decrease the fluidity, making the problem of the colder temperature worse.