Multiple Choice
In the context of transmembrane transport, which statement correctly distinguishes active transport from passive transport?
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9. Transport Across Membranes
Principles of Transmembrane Transport
Multiple Choice
In most cells, which molecule is directly used as the immediate energy source to drive primary active transport across membranes?
A
NADH
B
Glucose
C
ADP
D
ATP
Verified step by step guidance1
Understand the concept of primary active transport: it is a process where molecules are moved across a cell membrane against their concentration gradient using energy directly from a molecule.
Recall that the immediate energy source for most cellular processes, including primary active transport, is a high-energy molecule that can release energy quickly upon hydrolysis.
Evaluate the options: NADH is mainly involved in electron transport and energy production, glucose is a fuel molecule but not directly used for energy in transport, and ADP is a lower-energy molecule formed after ATP loses a phosphate group.
Recognize that ATP (adenosine triphosphate) is the molecule that provides energy by hydrolyzing its terminal phosphate bond, releasing energy that drives the transport proteins in the membrane.
Conclude that ATP is the direct and immediate energy source used to power primary active transport across membranes.
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