This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
The transition temperature of lipid bilayers of the cell membrane is increased by 
Select and explain. 
A. Cholesterol, B. Saturated fatty acids, C. Hydrocarbons, D. Unsaturated fatty acids
B: Saturated fatty acids
Answer: B: Saturated fatty acids 
Explanation: The temperature at which the crystalline or gel-like state of membrane structures turns into fluid-like the state is known as Transition temperature. Higher the transition temperature, lower the fluidity of the membrane. The transition temperature is increased maximum by the more saturated fatty acids which interact with each other through their long chains strongly and results in lesser fluidity.