Multiple Choice
Which of the following statements correctly describes the role of transpiration in the cohesion-tension theory of water transport in plants?
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9. Photosynthesis
Introduction to Photosynthesis
Multiple Choice
Which of the following correctly places in order the steps that occur as dehydration develops in a plant during photosynthesis?
A
Photosynthetic rate increases → Stomata open → CO\(_2\) uptake increases → Photorespiration decreases
B
Stomata close → CO\(_2\) uptake increases → Photosynthetic rate increases → Photorespiration decreases
C
Stomata open → CO\(_2\) uptake decreases → Photosynthetic rate drops → Photorespiration increases
D
Stomata close → CO\(_2\) uptake decreases → Photosynthetic rate drops → Photorespiration increases
Verified step by step guidance1
Step 1: Understand the context of the problem. Dehydration in plants occurs when water availability decreases, leading to physiological changes that impact photosynthesis and related processes.
Step 2: Recall the role of stomata in plants. Stomata are small openings on the surface of leaves that regulate gas exchange, including the uptake of CO\(_2\) and the release of water vapor. When a plant experiences dehydration, stomata typically close to conserve water.
Step 3: Analyze the impact of stomatal closure. When stomata close, CO\(_2\) uptake decreases because the plant can no longer efficiently exchange gases with the environment. This reduction in CO\(_2\) availability limits the photosynthetic rate.
Step 4: Connect the decrease in photosynthetic rate to photorespiration. As photosynthesis slows down due to reduced CO\(_2\) uptake, oxygen becomes more competitive for the enzyme RuBisCO, leading to an increase in photorespiration. Photorespiration is a process that consumes energy and reduces the efficiency of photosynthesis.
Step 5: Verify the sequence of events. The correct order is: Stomata close → CO\(_2\) uptake decreases → Photosynthetic rate drops → Photorespiration increases. This sequence aligns with the physiological responses of plants to dehydration during photosynthesis.
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