This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cell Physiology and Intercellular Connections, Subject name: Physiology
Function of cholesterol in plasma membrane - 
Select and explain. 
A. Helps in transport of ions, B. Helps in exocytosis, C. Maintains fluidity, D. Helps in synthesis of bile acids
C: Maintains fluidity
Answer: C: Maintains fluidity 
Explanation: Ans. is 'c' i.e.. Maintains fluidity o Roles of cholesterole in cell membrane areCholesterol modifies the fluidity of membrane in two wayAt temperatures below Tm - Increases fluidity.At iemperatures above Tm - Decreases fluidity.Cholesterol affects essential cellular functions through the modulation of particular membrane enzymes.Cholesterol provides cell membrane some extra support.o Option d requires specific mention here. Bile acids are derived from cholesterol. But it is not in plasma membrane, rather it is from intracellular cholesterol.