This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: membrane structure and function, Subject name: Biochemistry
Biological Cell membrane contains all the following except 
Select and explain. 
A. Steroid receptors, B. Prostaglandins, C. Cholesterol, D. Cytochrome
A: Steroid receptors
Answer: A: Steroid receptors 
Explanation: Membranes are mainly made up of lipids, proteins and small amount of carbohydrates. The contents of these compounds vary according to the nature of the membrane. The carbohydrates are present as glycoproteins and glycolipids. Phospholipids are the most common lipids present and they are amphipathic in nature. Cell membranes also contain cholesterol.Ref: DM Vasudevan, page no: 11