Multiple Choice
Which of the following transport proteins transports two molecules across the membrane in the same direction?
9. Transport Across Membranes
Passive Transport: Diffusion and Osmosis
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The plasma membrane by itself is impermeable to all charged molecules.
A
True
B
False
Verified step by step guidance1
Understand the structure of the plasma membrane: The plasma membrane is composed of a phospholipid bilayer with embedded proteins. The hydrophobic core of the bilayer acts as a barrier to most polar and charged molecules.
Consider the nature of charged molecules: Charged molecules, such as ions, are hydrophilic and cannot easily pass through the hydrophobic core of the lipid bilayer without assistance.
Identify the role of membrane proteins: While the lipid bilayer is impermeable to charged molecules, membrane proteins such as channels and transporters facilitate the movement of these molecules across the membrane.
Evaluate the statement: The statement 'The plasma membrane by itself is impermeable to all charged molecules' is assessing the inherent properties of the lipid bilayer without considering the role of proteins.
Conclude based on the evaluation: Since the lipid bilayer alone does not allow charged molecules to pass through, the statement is true when considering the membrane without the aid of proteins.
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