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NEET Questions / Botany / Photosynthesis in Higher Plants / Factors Affect Photosynthesis
A researcher exposes two genetically identical plants to different light intensities. Plant A receives high intensity monochromatic red light, while Plant B receives low intensity polychromatic light. Assuming all other factors are optimal, which statement is MOST likely true regarding the quantum yield of photosystem II (ΦPSII)?
Plant A will likely have a higher ΦPSII than Plant B.
Plant B will likely have a higher ΦPSII than Plant A.
The ΦPSII will be approximately equal in both plants.
The ΦPSII will be zero in both plants due to the different light conditions.
Under conditions of high temperature and drought stress, a plant closes its stomata to conserve water. Which of the following is the MOST DIRECT consequence on the Calvin cycle?
Increased photorespiration due to oxygen accumulation.
Enhanced ATP synthesis due to increased proton gradient.
Reduced availability of CO2 limits carboxylation, leading to a decrease in RuBP regeneration.
Increased activity of Rubisco due to higher substrate concentration.
A C4 plant and a CAM plant are grown under identical environmental conditions. Which statement BEST describes their relative water use efficiency (WUE) and photosynthetic rates under prolonged high light intensity and high temperature?
The C4 plant will have both higher WUE and a higher photosynthetic rate than the CAM plant.
The CAM plant will have higher WUE than the C4 plant, but the C4 plant will have a higher photosynthetic rate.
The C4 plant will have higher WUE than the CAM plant, but the CAM plant will have a higher photosynthetic rate.
The CAM plant will have both higher WUE and a higher photosynthetic rate than the C4 plant.
Which of the following combinations of factors would MOST SIGNIFICANTLY limit the rate of photosynthesis in a typical C3 plant?
Low light intensity, high CO2 concentration, and optimal temperature
High light intensity, low O2 concentration, and high humidity
High temperature, low CO2 concentration, and water stress
Low temperature, high CO2 concentration, and waterlogged soil
How does the availability of magnesium ions (Mg2+) directly influence the light-dependent reactions of photosynthesis?
Mg2+ acts as a cofactor for Rubisco, facilitating CO2 fixation.
Mg2+ is a component of the electron transport chain, mediating electron flow.
Mg2+ is essential for chlorophyll structure and function, influencing light absorption and energy transfer.
Mg2+ regulates stomatal opening and closing, controlling CO2 uptake.
A mutation affects a plant's ability to synthesize carotenoids. Which of the following would be the MOST LIKELY consequence for photosynthesis under high light intensity?
Enhanced light absorption and increased photosynthetic rate.
Increased damage to chlorophyll and photosystems due to excessive light energy.
No significant change in photosynthetic rate or chlorophyll integrity.
Shift in the absorption spectrum towards longer wavelengths.
Which of the following factors does NOT directly affect the rate of photosynthesis?
Light intensity
Carbon dioxide concentration
Temperature
Soil pH
Increasing the concentration of carbon dioxide around a plant will MOST likely increase the rate of photosynthesis up to a certain point, because:
CO2 is a reactant in photosynthesis.
CO2 is a product of photosynthesis.
CO2 absorbs light energy.
CO2 regulates the opening and closing of stomata.
Which of these is required for photosynthesis?
Chlorophyll
Mitochondria
Oxygen
Glucose
At very high light intensities, the rate of photosynthesis:
May decrease due to photoinhibition
Increases indefinitely
Remains constant
Decreases proportionally to temperature
