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Multiple Choice
Which of the following is an example of a passive transport process in cells?
A
Glucose uptake via sodium-glucose symporter
B
Endocytosis of large molecules
C
Sodium-potassium pump activity
D
Diffusion of oxygen across the plasma membrane
Verified step by step guidance
1
Understand the concept of passive transport: Passive transport is the movement of substances across a cell membrane without the use of energy (ATP). It relies on the concentration gradient, moving substances from areas of high concentration to areas of low concentration.
Review the examples provided in the question: Glucose uptake via sodium-glucose symporter, endocytosis of large molecules, sodium-potassium pump activity, and diffusion of oxygen across the plasma membrane.
Analyze each option: Glucose uptake via sodium-glucose symporter involves active transport because it uses energy indirectly by coupling with sodium movement. Endocytosis of large molecules is an active process requiring energy to engulf substances. Sodium-potassium pump activity is also active transport, as it directly uses ATP to move ions against their concentration gradients.
Focus on diffusion of oxygen across the plasma membrane: Diffusion is a classic example of passive transport. Oxygen moves freely across the membrane from an area of high concentration (outside the cell) to an area of low concentration (inside the cell) without requiring energy.
Conclude that diffusion of oxygen across the plasma membrane is the correct example of passive transport, as it aligns with the definition and characteristics of passive transport processes.