Multiple Choice
In the context of principles of transmembrane transport, what best defines secondary active transport?
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9. Transport Across Membranes
Principles of Transmembrane Transport
Multiple Choice
In the context of principles of transmembrane transport, how is active transport similar to facilitated diffusion?
A
Both use ATP hydrolysis as their energy source for every transport event.
B
Both move solutes directly through the lipid bilayer without involvement of membrane proteins.
C
Both always move solutes down their electrochemical gradient and therefore never require an energy input.
D
Both move solutes across the membrane using specific transmembrane transport proteins that provide a selective pathway.
Verified step by step guidance1
Step 1: Understand the basic definitions of active transport and facilitated diffusion. Active transport moves solutes against their electrochemical gradient and requires energy, while facilitated diffusion moves solutes down their gradient without energy input.
Step 2: Identify the role of membrane proteins in both processes. Both active transport and facilitated diffusion use specific transmembrane transport proteins to move solutes across the membrane.
Step 3: Recognize that these transport proteins provide a selective pathway, allowing only certain solutes to pass through, which increases the specificity and efficiency of transport.
Step 4: Note the key difference that active transport requires energy (often from ATP hydrolysis) to move solutes against their gradient, whereas facilitated diffusion does not require energy and moves solutes down their gradient.
Step 5: Conclude that the similarity lies in the use of specific transmembrane proteins to facilitate solute movement, not in the energy requirement or direction of transport.
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