Questions on the Calvin Cycle
20 multiple choice questions on the Calvin Cycle, each numbered and followed by an answer key at the end.
Multiple Choice Questions: Calvin Cycle
1. What is the Calvin Cycle also known as?
A) Krebs Cycle
B) Light-dependent reaction
C) Light-independent reaction
D) Electron Transport Chain
2. Where does the Calvin Cycle take place?
A) Thylakoid membrane
B) Mitochondrial matrix
C) Cytoplasm
D) Stroma of the chloroplast
3. Which gas is fixed during the Calvin Cycle?
A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Hydrogen
4. What is the primary product of the Calvin Cycle?
A) Oxygen
B) ATP
C) Glucose
D) Water
5. Which enzyme catalyzes the fixation of CO₂ in the Calvin Cycle?
A) ATP synthase
B) Rubisco
C) Kinase
D) DNA polymerase
6. How many turns of the Calvin Cycle are required to produce one glucose molecule?
A) 2
B) 3
C) 6
D) 12
7. What are the three main phases of the Calvin Cycle?
A) Initiation, propagation, termination
B) Fixation, reduction, regeneration
C) Glycolysis, fermentation, respiration
D) Absorption, transport, release
8. Which molecules produced in the light-dependent reactions are used in the Calvin Cycle?
A) CO₂ and O₂
B) ATP and NADPH
C) Glucose and H₂O
D) Rubisco and chlorophyll
9. What happens during the carbon fixation phase?
A) CO₂ is converted into glucose directly
B) CO₂ is attached to a 5-carbon sugar
C) ATP is produced
D) NADPH is oxidized
10. What is the 5-carbon compound that reacts with CO₂ in the Calvin Cycle?
A) Glucose
B) Ribose
C) Ribulose bisphosphate (RuBP)
D) G3P
11. How many molecules of CO₂ are needed to make one molecule of glucose?
A) 3
B) 4
C) 5
D) 6
12. What is G3P (glyceraldehyde-3-phosphate)?
A) A pigment
B) A waste product
C) A sugar used to make glucose
D) An enzyme
13. What happens to the G3P not used to form glucose?
A) It's excreted
B) It's converted into ATP
C) It's used to regenerate RuBP
D) It's broken down
14. How many ATP molecules are used in the Calvin Cycle to produce one glucose?
A) 12
B) 18
C) 24
D) 6
15. How many NADPH molecules are required to produce one glucose molecule in the Calvin Cycle?
A) 6
B) 12
C) 18
D) 24
16. Which of the following does NOT occur in the Calvin Cycle?
A) Carbon fixation
B) ATP consumption
C) Oxygen production
D) NADPH oxidation
17. The Calvin Cycle is a part of which larger process?
A) Cellular respiration
B) Glycolysis
C) Photosynthesis
D) Fermentation
18. Which statement is true about the Calvin Cycle?
A) It only occurs in the dark
B) It depends on products from the light reactions
C) It produces ATP
D) It releases carbon dioxide
19. Why is the Calvin Cycle called a "cycle"?
A) It repeats endlessly without change
B) It has no beginning or end
C) It regenerates the starting molecule, RuBP
D) It does not use energy
20. Which of the following best summarizes the Calvin Cycle?
A) Energy is made from sunlight
B) Glucose is broken down into carbon dioxide
C) CO₂ is fixed into organic molecules using ATP and NADPH
D) ATP is created through fermentation
Answer Key
1. C – Light-independent reaction
2. D – Stroma of the chloroplast
3. C – Carbon dioxide
4. C – Glucose
5. B – Rubisco
6. C – 6
7. B – Fixation, reduction, regeneration
8. B – ATP and NADPH
9. B – CO₂ is attached to a 5-carbon sugar
10. C – Ribulose bisphosphate (RuBP)
11. D – 6
12. C – A sugar used to make glucose
13. C – It's used to regenerate RuBP
14. B – 18
15. B – 12
16. C – Oxygen production
17. C – Photosynthesis
18. B – It depends on products from the light reactions
19. C – It regenerates the starting molecule, RuBP
20. C – CO₂ is fixed into organic molecules using ATP and NADPH
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