Multiple Choice
Simple diffusion requires __________.
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9. Transport Across Membranes
Passive Transport: Diffusion and Osmosis
Multiple Choice
In the context of passive transport, does facilitated diffusion require an input of cellular energy (ATP) to move solutes across a membrane?
A
No; facilitated diffusion occurs only by simple diffusion directly through the lipid bilayer without any proteins.
B
Yes; facilitated diffusion requires ATP hydrolysis to move solutes through carrier proteins.
C
No; facilitated diffusion moves solutes down their concentration (or electrochemical) gradient through membrane proteins without ATP.
D
Yes; facilitated diffusion requires energy because solutes move from low to high concentration.
Verified step by step guidance1
Step 1: Understand the definition of passive transport. Passive transport is the movement of molecules across a cell membrane without the input of cellular energy (ATP), typically moving down their concentration gradient.
Step 2: Recognize that facilitated diffusion is a type of passive transport where specific membrane proteins (such as channel or carrier proteins) assist the movement of solutes across the membrane.
Step 3: Note that in facilitated diffusion, solutes move from an area of higher concentration to an area of lower concentration, following their concentration or electrochemical gradient.
Step 4: Clarify that facilitated diffusion does not require ATP because the movement is driven by the natural gradient, unlike active transport which moves solutes against their gradient and requires energy.
Step 5: Conclude that facilitated diffusion involves membrane proteins but does not require energy input, distinguishing it from active transport mechanisms.
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