Multiple Choice
Which of the following is an advantage of the C4 pathway over the C3 pathway in plants?
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9. Photosynthesis
C3, C4 & CAM Plants
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Which photosynthetic pathway allows carbon dioxide to enter leaves only at night?
A
CAM pathway
B
C3 pathway
C
Photorespiration
D
C4 pathway
Verified step by step guidance1
Understand the context of the problem: Photosynthesis is the process by which plants convert light energy into chemical energy. Different plants have evolved distinct pathways to fix carbon dioxide (CO2) depending on environmental conditions.
Review the key photosynthetic pathways: The C3 pathway is the most common and occurs in most plants. The C4 pathway is an adaptation to high light intensity and temperature. The CAM (Crassulacean Acid Metabolism) pathway is an adaptation to arid conditions, allowing plants to conserve water.
Focus on the CAM pathway: In CAM plants, stomata (pores on the leaf surface) open at night to take in CO2, minimizing water loss. The CO2 is stored as an organic acid and used during the day for photosynthesis when the stomata are closed.
Eliminate incorrect options: The C3 pathway and C4 pathway involve CO2 uptake during the day, not at night. Photorespiration is a process that occurs when the enzyme Rubisco fixes oxygen instead of CO2, leading to energy loss, and is unrelated to nighttime CO2 uptake.
Conclude that the CAM pathway is the correct answer, as it specifically allows CO2 to enter leaves at night, making it an adaptation to conserve water in dry environments.
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C3, C4 & CAM Plants practice set
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