A desert plant maintains stomata closure during the day and opens them at night, fixing CO2 into malic acid. This adaptation is characteristic of which photosynthetic pathway?
Q.82Medium
In the light-dependent reactions, non-cyclic photophosphorylation produces ATP and NADPH in a ratio of approximately:
Q.83Easy
Stomatal opening is primarily regulated by the accumulation of which osmotically active solute in guard cells?
Q.84Medium
A seedling grown under continuous red light shows etiolation symptoms. This is primarily because:
Q.85Medium
The quantum requirement for photosynthesis (minimum number of photons needed to fix one CO2) is approximately:
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Q.86Hard
In the absence of light, what happens to the pH gradient across the thylakoid membrane?
Q.87Hard
Which photosystem has a lower reduction potential for its reaction center chlorophyll (P700 vs P680)?
Q.88Medium
A plant exhibits wilting despite adequate soil moisture. The most likely explanation involves:
Q.89Hard
The Emerson effect demonstrates that photosynthesis efficiency increases when plants are exposed to both red and far-red light together compared to either alone. This is explained by:
Q.90Easy
Which of the following correctly describes the role of carotenoids in photosynthesis?
Q.91Medium
Under conditions of high light intensity and stomatal closure, what is the primary fate of electrons in the thylakoid?
Q.92Easy
The photoperiodic response in plants (flowering) is primarily detected by which photoreceptor?
Q.93Medium
In photorespiration, glycolate (2-phosphoglycolate) is initially oxidized in peroxisomes. This process consumes O2 but generates no ATP. What is the primary consequence?
Q.94Easy
A variegated plant leaf shows white and green patches. Which organelle dysfunction is responsible for white patches?
Q.95Hard
During the S-state transitions in the oxygen-evolving complex, the manganese cluster undergoes sequential oxidation. How many oxidation steps occur before O2 is released?
Q.96Easy
Which of the following statements about transpiration pull is correct?
Q.97Medium
A plant grown under continuous red light shows reduced stem elongation compared to white light. Which photoreceptor is primarily responsible for this response?
Q.98Medium
In C4 plants, the first stable product of photosynthesis is oxaloacetate (4-carbon compound). Which of the following is the primary advantage of this mechanism in tropical environments?
Q.99Hard
A research study on stomatal regulation shows that ABA (abscisic acid) concentration increases 100-fold in guard cells during drought stress. Which of the following correctly describes the mechanism?
Q.100Medium
During seed germination, reserve mobilization occurs through enzyme activation. Which hormone primarily promotes the synthesis of α-amylase in the aleurone layer of cereal grains?
