Multiple Choice
Which of the following scenarios best illustrates a cell performing exocytosis?
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13. Intracellular Protein Transport
Exocytosis
Multiple Choice
In eukaryotic cells, is exocytosis considered passive transport or active transport?
A
Active transport, because vesicle docking and membrane fusion require cellular energy (e.g., ATP/GTP) and cytoskeletal machinery.
B
Neither, because exocytosis is a type of facilitated diffusion through membrane transporters.
C
Passive transport, because exocytosis always occurs down a concentration gradient without energy input.
D
Passive transport, because substances move out of the cell by simple diffusion through the lipid bilayer.
Verified step by step guidance1
Understand the definition of passive and active transport: Passive transport does not require cellular energy and moves substances down their concentration gradient, while active transport requires energy input to move substances against their gradient or to facilitate complex processes.
Recall the process of exocytosis in eukaryotic cells: It involves vesicles transporting materials to the plasma membrane, docking, and fusing with the membrane to release contents outside the cell.
Recognize that exocytosis requires energy: The vesicle movement, docking, and membrane fusion depend on cellular energy sources such as ATP or GTP and involve cytoskeletal elements like microtubules and motor proteins.
Compare exocytosis to passive transport mechanisms: Unlike simple diffusion or facilitated diffusion, exocytosis is not just movement through membrane channels but an active, energy-dependent process.
Conclude that exocytosis is a form of active transport because it requires energy and cellular machinery to move substances out of the cell.
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