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Photosynthesis in Higher Plants

Dark Reactions: Calvin Cycle and C3 Pathway Practice Questions

20 free Dark Reactions: Calvin Cycle and C3 Pathway practice questions for the NCERT Biology, each with the correct answer and a detailed explanation. Open any question below, or take the full set as an interactive quiz.

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All Dark Reactions: Calvin Cycle and C3 Pathway questions

20 questions
  1. Q1. Which of the following is the primary CO2 acceptor molecule in the C3 pathway (Calvin Cycle)?
  2. Q2. The first stable product of the Calvin cycle in C3 plants is a:
  3. Q3. The Calvin cycle proceeds in three distinct stages. What is the correct chronological order of these stages?
  4. Q4. How many molecules of ATP and NADPH are required for every molecule of CO2 fixed during the reduction step of the Calvin cycle?
  5. Q5. To produce one molecule of glucose, how many 'turns' of the Calvin cycle are required?
  6. Q6. Regeneration of one molecule of RuBP requires the expenditure of how many ATP molecules?
  7. Q7. Which enzyme is the most abundant protein on Earth and catalyzes the carboxylation of RuBP?
  8. Q8. What is the total energy requirement (ATP and NADPH) for the synthesis of one molecule of glucose in the C3 pathway?
  9. Q9. In which part of the chloroplast do the 'Dark Reactions' or biosynthetic phase occur?
  10. Q10. During the Calvin cycle, the reduction of 3-phosphoglyceric acid (PGA) leads to the formation of:
  11. Q11. Which of the following statements about the Calvin cycle is FALSE?
  12. Q12. The carboxylation reaction of the Calvin cycle results in two molecules of:
  13. Q13. In the C3 pathway, if the concentration of CO2 becomes very low and O2 is high, RuBisCO starts acting as an:
  14. Q14. Which of the following is utilized during the regeneration phase of the Calvin cycle?
  15. Q15. Melvin Calvin used which radioactive isotope to trace the path of carbon in algal photosynthesis?
  16. Q16. For the net export of one molecule of triose phosphate (G3P) from the Calvin cycle, how many turns of the cycle are needed?
  17. Q17. What is the primary reason the 'Reduction' phase is called so?
  18. Q18. Which of these is NOT a direct product of the Calvin cycle?
  19. Q19. If a C3 plant is provided with CO2 containing 14C, which molecule would show radioactivity first?
  20. Q20. In the C3 pathway, the conversion of 3-phosphoglyceric acid to 1,3-bisphosphoglyceric acid involves: