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Multiple Choice
Which of the following incorrectly describes mechanisms of CO$_2$ transport in plants during photosynthesis?
A
CO$_2$ is transported from the atmosphere into the leaf through stomata by diffusion.
B
CO$_2$ dissolves in the aqueous phase of the mesophyll cell cytoplasm before entering the chloroplast.
C
CO$_2$ is fixed by the enzyme RuBisCO in the Calvin cycle.
D
CO$_2$ is actively pumped into chloroplasts using ATP.
Verified step by step guidance
1
Understand the context: The question is about mechanisms of CO$_2$ transport in plants during photosynthesis. Photosynthesis involves the uptake of CO$_2$ from the atmosphere, its diffusion into the leaf, and its fixation in the Calvin cycle. The question asks which statement is incorrect.
Review the first statement: 'CO$_2$ is transported from the atmosphere into the leaf through stomata by diffusion.' This is correct because CO$_2$ enters the leaf through stomata via passive diffusion, driven by a concentration gradient.
Review the second statement: 'CO$_2$ dissolves in the aqueous phase of the mesophyll cell cytoplasm before entering the chloroplast.' This is also correct because CO$_2$ dissolves in the cytoplasm and diffuses into the chloroplast where photosynthesis occurs.
Review the third statement: 'CO$_2$ is fixed by the enzyme RuBisCO in the Calvin cycle.' This is correct because RuBisCO is the enzyme responsible for fixing CO$_2$ into organic molecules during the Calvin cycle.
Review the fourth statement: 'CO$_2$ is actively pumped into chloroplasts using ATP.' This is incorrect because CO$_2$ enters the chloroplast by diffusion, not active transport, and ATP is not used for this process. This makes the fourth statement the correct answer to the question.