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Multiple Choice
In C3 plants, the conservation of water promotes _____.
A
increased photosynthetic efficiency
B
greater stomatal opening
C
enhanced carbon fixation
D
photorespiration
Verified step by step guidance
1
Understand the context: C3 plants are a type of plant that uses the Calvin cycle for carbon fixation during photosynthesis. They are named 'C3' because the first stable product of carbon fixation is a three-carbon compound, 3-phosphoglycerate.
Recognize the relationship between water conservation and stomatal behavior: When water conservation is necessary, C3 plants close their stomata to reduce water loss. Stomata are small openings on the leaf surface that allow gas exchange, including the intake of CO2 and release of O2.
Analyze the impact of stomatal closure: When stomata close, the intake of CO2 decreases, leading to a lower concentration of CO2 inside the leaf. This disrupts the normal Calvin cycle and increases the oxygen concentration relative to CO2.
Understand photorespiration: Photorespiration occurs when the enzyme RuBisCO binds to oxygen (O2) instead of carbon dioxide (CO2) due to the reduced CO2 levels. This process is less efficient because it does not produce sugars and instead consumes energy and releases CO2.
Conclude the connection: Water conservation in C3 plants promotes photorespiration because the closure of stomata reduces CO2 availability, forcing RuBisCO to interact with O2, which leads to this less efficient process.