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Multiple Choice
Which of the following statements is correct about a biological membrane that is fluid?
A
Proteins within the membrane can move laterally along the plane of the membrane.
B
The membrane is impermeable to all substances.
C
Cholesterol decreases the fluidity of the membrane at all temperatures.
D
The membrane is composed of a rigid structure of phospholipids.
Verified step by step guidance
1
Understand the concept of membrane fluidity: Biological membranes are composed of a lipid bilayer with embedded proteins. The fluidity of the membrane refers to the ability of lipids and proteins to move within the layer, which is crucial for membrane function.
Analyze the role of proteins in the membrane: Proteins can move laterally within the lipid bilayer, allowing for various functions such as signaling, transport, and maintaining the structure of the membrane.
Evaluate the statement about impermeability: A completely impermeable membrane would not allow any substances to pass through, which is not typical for biological membranes as they need to allow selective permeability for cellular function.
Consider the role of cholesterol: Cholesterol can both increase and decrease membrane fluidity depending on the temperature. It stabilizes the membrane by preventing it from becoming too fluid at high temperatures and too rigid at low temperatures.
Assess the structure of phospholipids: Phospholipids form a bilayer that is not rigid but rather flexible, allowing for the dynamic nature of the membrane. This flexibility is essential for the membrane's fluidity and function.