Multiple Choice
In the context of passive transport, facilitated diffusion is used to transport which type of substance across a cell membrane?
48
views
9. Transport Across Membranes
Passive Transport: Diffusion and Osmosis
Multiple Choice
Which of the following statements about diffusion is true?
A
Diffusion causes molecules to move from regions of lower concentration to regions of higher concentration until a gradient is established.
B
Diffusion moves molecules only through membrane transport proteins and cannot occur directly through the lipid bilayer.
C
Net movement of molecules occurs from regions of higher concentration to regions of lower concentration due to random thermal motion.
D
Diffusion requires ATP hydrolysis to move molecules down their concentration gradient.
Verified step by step guidance1
Step 1: Understand the concept of diffusion. Diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration, driven by the random thermal motion of molecules.
Step 2: Analyze the first statement: 'Diffusion causes molecules to move from regions of lower concentration to regions of higher concentration until a gradient is established.' This contradicts the basic principle of diffusion, which moves molecules down their concentration gradient, not up.
Step 3: Evaluate the second statement: 'Diffusion moves molecules only through membrane transport proteins and cannot occur directly through the lipid bilayer.' This is not entirely true because small nonpolar molecules can diffuse directly through the lipid bilayer without the need for transport proteins.
Step 4: Consider the third statement: 'Net movement of molecules occurs from regions of higher concentration to regions of lower concentration due to random thermal motion.' This aligns with the fundamental definition of diffusion and is therefore true.
Step 5: Review the fourth statement: 'Diffusion requires ATP hydrolysis to move molecules down their concentration gradient.' Diffusion is a passive process and does not require energy input such as ATP hydrolysis.
Related Videos
Related Practice
