Final answer:
Saturated fatty acids in phospholipid tails and cholesterol help maintain membrane fluidity in low temperatures.
Step-by-step explanation:
In low temperatures, the saturated fatty acids in phospholipid tails help maintain membrane fluidity. When the temperatures decrease, the straight tails of saturated fatty acids press in on each other, making a dense and rigid membrane. On the other hand, unsaturated fatty acids with their kinks maintain some space between phospholipid molecules, preserving fluidity in the membrane.
Additionally, cholesterol acts as a buffer and helps maintain membrane fluidity in low temperatures. It prevents lower temperatures from inhibiting fluidity and extends the temperature range in which the membrane is appropriately fluid and functional.