1. What is the primary pigment responsible for photosynthesis in plants?
- a) Chlorophyll
- b) Carotenoids
- c) Xanthophyll
- d) Anthocyanin
- Answer: a) Chlorophyll
Explanation: Chlorophyll is the green pigment in plants that captures light energy for photosynthesis.
2. During photosynthesis, which gas is released as a by-product?
- a) Carbon dioxide
- b) Oxygen
- c) Nitrogen
- d) Hydrogen
- Answer: b) Oxygen
Explanation: Oxygen is released as a by-product when water is split during the light-dependent reactions of photosynthesis.
3. What is the first product formed during the Calvin cycle?
- a) 3-phosphoglycerate (3-PGA)
- b) Glucose
- c) Ribulose bisphosphate (RuBP)
- d) Fructose
- Answer: a) 3-phosphoglycerate (3-PGA)
Explanation: 3-PGA is the first stable compound formed in the Calvin cycle after the fixation of carbon dioxide.
4. Which process in photosynthesis involves the splitting of water molecules?
- a) Calvin cycle
- b) Photolysis
- c) Glycolysis
- d) Respiration
- Answer: b) Photolysis
Explanation: Photolysis occurs during the light-dependent reactions, where water molecules are split to release oxygen, electrons, and protons.
5. The light-independent reactions of photosynthesis occur in which part of the chloroplast?
- a) Stroma
- b) Thylakoid membrane
- c) Grana
- d) Cytoplasm
- Answer: a) Stroma
Explanation: The Calvin cycle (light-independent reactions) takes place in the stroma of the chloroplast.
6. Which enzyme is crucial for carbon fixation in the Calvin cycle?
- a) ATP synthase
- b) Rubisco
- c) NADP reductase
- d) Phosphofructokinase
- Answer: b) Rubisco
Explanation: Rubisco (Ribulose bisphosphate carboxylase/oxygenase) catalyzes the first step of carbon fixation in the Calvin cycle.
7. What is the source of oxygen released during photosynthesis?
- a) Water
- b) Carbon dioxide
- c) Glucose
- d) ATP
- Answer: a) Water
Explanation: Oxygen released during photosynthesis comes from the splitting of water molecules during photolysis.
8. Which of the following is NOT a product of the light-dependent reactions of photosynthesis?
- a) Glucose
- b) ATP
- c) NADPH
- d) Oxygen
- Answer: a) Glucose
Explanation: Glucose is produced during the Calvin cycle, not in the light-dependent reactions.
9. What wavelength of light is most effective for photosynthesis?
- a) Green light
- b) Red and blue light
- c) Yellow light
- d) Infrared light
- Answer: b) Red and blue light
Explanation: Chlorophyll absorbs red and blue wavelengths of light most effectively, driving the process of photosynthesis.
10. In C4 plants, the initial carbon fixation occurs in which part of the cell?
- a) Stroma
- b) Grana
- c) Mesophyll cells
- d) Bundle sheath cells
- Answer: c) Mesophyll cells
Explanation: In C4 plants, carbon fixation first occurs in the mesophyll cells before being transferred to the bundle sheath cells for the Calvin cycle.
11. What is the main function of photosystem I in photosynthesis?
- a) Splitting of water
- b) ATP production
- c) NADPH production
- d) Carbon fixation
- Answer: c) NADPH production
Explanation: Photosystem I primarily helps in the production of NADPH, which is used in the Calvin cycle.
12. The energy currency of the cell, ATP, is synthesized during which stage of photosynthesis?
- a) Light-dependent reactions
- b) Calvin cycle
- c) Glycolysis
- d) Photolysis
- Answer: a) Light-dependent reactions
Explanation: ATP is synthesized during the light-dependent reactions through the process of photophosphorylation.
13. Which molecule is regenerated in the Calvin cycle that allows the cycle to continue?
- a) Ribulose bisphosphate (RuBP)
- b) Glucose
- c) NADPH
- d) ATP
- Answer: a) Ribulose bisphosphate (RuBP)
Explanation: RuBP is regenerated in the Calvin cycle to fix another molecule of CO2, allowing the cycle to continue.
14. Which type of photosynthesis is most efficient in hot and dry conditions?
- a) C4 photosynthesis
- b) C3 photosynthesis
- c) CAM photosynthesis
- d) Photorespiration
- Answer: a) C4 photosynthesis
Explanation: C4 photosynthesis is more efficient in hot and dry conditions as it minimizes photorespiration.
15. What is the primary difference between C3 and C4 plants?
- a) Number of carbon atoms in glucose
- b) Pathway of carbon fixation
- c) Chloroplast structure
- d) Presence of Rubisco enzyme
- Answer: b) Pathway of carbon fixation
Explanation: C3 plants fix carbon directly through the Calvin cycle, while C4 plants first fix carbon into a four-carbon compound.
16. In CAM plants, when does carbon fixation occur?
- a) During the day
- b) At night
- c) In the morning
- d) In the evening
- Answer: b) At night
Explanation: CAM plants fix carbon at night to reduce water loss in hot, arid environments.
17. Which compound is the final product of the Calvin cycle?
- a) Pyruvate
- b) Glucose
- c) ATP
- d) NADPH
- Answer: b) Glucose
Explanation: The final product of the Calvin cycle is glucose, which is synthesized from G3P.
18. Which structure in the plant cell is the site of photosynthesis?
- a) Mitochondria
- b) Chloroplast
- c) Nucleus
- d) Vacuole
- Answer: b) Chloroplast
Explanation: Photosynthesis occurs in the chloroplasts, where chlorophyll captures light energy.
19. What is the primary purpose of the Calvin cycle?
- a) Water splitting
- b) Sugar synthesis
- c) Oxygen production
- d) Light absorption
- Answer: b) Sugar synthesis
Explanation: The Calvin cycle is responsible for synthesizing glucose using the energy from ATP and NADPH.
20. Which gas is consumed during photosynthesis?
- a) Carbon dioxide
- b) Oxygen
- c) Nitrogen
- d) Methane
- Answer: a) Carbon dioxide
Explanation: Carbon dioxide is consumed during photosynthesis and is fixed into glucose through the Calvin cycle.