1. Which of the following is a primary characteristic of C4 plants?
a) They perform photosynthesis at night
b) They have a high rate of photorespiration
c) They separate carbon fixation and Calvin cycle spatially
d) They perform photosynthesis using only mesophyll cells
Answer: c) They separate carbon fixation and Calvin cycle spatially
2. Which enzyme is responsible for the initial fixation of carbon in C4 plants?
a) Rubisco
b) PEP carboxylase
c) Phosphoglycerate kinase
d) Aldolase
Answer: b) PEP carboxylase
3. In CAM plants, the Calvin cycle occurs during which time of the day?
a) Day
b) Night
c) Both day and night
d) Neither day nor night
Answer: b) Night
4. What is the main advantage of C4 and CAM pathways in arid environments?
a) Increased water loss
b) Reduced photorespiration
c) Higher oxygen production
d) Slower photosynthesis
Answer: b) Reduced photorespiration
5. In C4 plants, carbon dioxide is first fixed into which compound?
a) Glyceraldehyde 3-phosphate (G3P)
b) Oxaloacetate
c) Ribulose bisphosphate (RuBP)
d) Glucose
Answer: b) Oxaloacetate
6. Which of the following is characteristic of CAM plants?
a) They open stomata during the day
b) They fix carbon dioxide only at night
c) They only grow in wet environments
d) They do not use PEP carboxylase
Answer: b) They fix carbon dioxide only at night
7. Which of the following best describes the function of the C4 pathway in plants?
a) It increases the rate of photorespiration.
b) It minimizes the loss of water through transpiration.
c) It enhances the fixation of carbon dioxide by separating it spatially.
d) It requires high amounts of light energy for carbon fixation.
Answer: c) It enhances the fixation of carbon dioxide by separating it spatially.
8. What is the role of the enzyme PEP carboxylase in C4 plants?
a) It converts oxaloacetate to malate.
b) It fixes carbon dioxide into a 3-carbon compound.
c) It fixes carbon dioxide into a 4-carbon compound.
d) It helps in the conversion of glucose into starch.
Answer: c) It fixes carbon dioxide into a 4-carbon compound.
9. What is a common feature of both C4 and CAM plants?
a) Both perform photosynthesis without light.
b) Both reduce the loss of water during photosynthesis.
c) Both have high rates of photorespiration.
d) Both fix carbon during the day.
Answer: b) Both reduce the loss of water during photosynthesis.
10. The CAM pathway in plants involves which of the following?
a) Carbon dioxide fixation at night
b) Continuous stomatal opening during the day
c) Conversion of oxaloacetate to glucose during the day
d) The Calvin cycle and the light reaction happening simultaneously
Answer: a) Carbon dioxide fixation at night
11. In C4 plants, the Calvin cycle occurs in which cells?
a) Bundle sheath cells
b) Mesophyll cells
c) Both mesophyll and bundle sheath cells
d) Only root cells
Answer: a) Bundle sheath cells
12. CAM plants are most commonly found in which types of environments?
a) Wet, tropical rainforests
b) Cool, temperate regions
c) Hot and dry, arid environments
d) Aquatic environments
Answer: c) Hot and dry, arid environments
13. Why do C4 plants have an advantage in hot, sunny environments?
a) They reduce the need for transpiration.
b) They have a high tolerance to high temperatures.
c) They can fix carbon dioxide more efficiently and avoid photorespiration.
d) They do not require sunlight for photosynthesis.
Answer: c) They can fix carbon dioxide more efficiently and avoid photorespiration.
14. In which part of the leaf does the CAM pathway primarily occur?
a) Xylem
b) Stomata
c) Mesophyll cells
d) Phloem
Answer: c) Mesophyll cells
15. Which of the following best describes the role of CAM plants in arid environments?
a) They open their stomata during the day to conserve water.
b) They fix carbon during the day to minimize water loss.
c) They open stomata at night, fixing carbon and reducing water loss.
d) They avoid photosynthesis during the night.
Answer: c) They open stomata at night, fixing carbon and reducing water loss.
16. Which of the following is NOT a characteristic of C4 plants?
a) They have a high tolerance for high light intensity.
b) They perform carbon fixation in two separate cell types.
c) They use the Calvin cycle for carbon fixation.
d) They perform the C4 pathway in the mesophyll cells only.
Answer: d) They perform the C4 pathway in the mesophyll cells only.
17. Which of the following is a common example of a C4 plant?
a) Rice
b) Wheat
c) Corn
d) Potato
Answer: c) Corn
18. In CAM plants, the stored organic acids, such as malic acid, are converted back to carbon dioxide during which phase of photosynthesis?
a) Night phase
b) Day phase
c) Both day and night
d) Only during the light reaction
Answer: b) Day phase
19. Which of the following enzymes is involved in the CAM pathway for fixing carbon dioxide at night?
a) PEP carboxylase
b) Rubisco
c) Pyruvate kinase
d) Phosphofructokinase
Answer: a) PEP carboxylase
20. Why do CAM plants close their stomata during the day?
a) To conserve water by preventing excessive transpiration
b) To increase the uptake of carbon dioxide
c) To prevent oxygen buildup inside the plant
d) To allow the conversion of glucose into starch
Answer: a) To conserve water by preventing excessive transpiration
21. Which of the following is an example of a CAM plant?
a) Cactus
b) Sunflower
c) Tomato
d) Bamboo
Answer: a) Cactus
22. The C4 pathway evolved in plants primarily as a response to:
a) Low oxygen levels
b) High light intensity
c) High atmospheric carbon dioxide
d) Water stress
Answer: d) Water stress
23. What is the key difference between the C4 and CAM pathways?
a) C4 plants use light energy to fix carbon at night, while CAM plants do so during the day.
b) C4 plants fix carbon in two cells types while CAM plants fix carbon in a single cell at night.
c) C4 plants fix carbon in the mesophyll cells, while CAM plants do so in the phloem.
d) CAM plants do not require the Calvin cycle.
Answer: b) C4 plants fix carbon in two cells types while CAM plants fix carbon in a single cell at night.
24. CAM plants store carbon in the form of:
a) Starch
b) Glucose
c) Malic acid
d) Citric acid
Answer: c) Malic acid
25. The C4 pathway occurs mainly in which of the following plants?
a) Desert plants
b) Temperate grasses
c) Tropical grasses
d) Aquatic plants
Answer: c) Tropical grasses
26. CAM plants benefit from fixing carbon at night because:
a) Stomata remain closed during the day, preventing water loss.
b) Nighttime provides more light for photosynthesis.
c) They require more carbon dioxide during the day.
d) The night phase provides more oxygen for respiration.
Answer: a) Stomata remain closed during the day, preventing water loss.
27. Which of the following is true regarding the C4 pathway?
a) It involves the fixation of carbon in a single cell.
b) It is only found in plants that live in hot climates.
c) It minimizes photorespiration by separating carbon fixation and the Calvin cycle.
d) It reduces the need for sunlight.
Answer: c) It minimizes photorespiration by separating carbon fixation and the Calvin cycle.
28. In CAM plants, what happens during the night?
a) Carbon dioxide is fixed into a 3-carbon compound.
b) The plant undergoes the Calvin cycle.
c) Carbon dioxide is fixed into a 4-carbon compound.
d) Oxygen is absorbed through the stomata.
Answer: c) Carbon dioxide is fixed into a 4-carbon compound.
29. Which of the following is true about CAM plants?
a) They open their stomata only during the day.
b) They perform photosynthesis exclusively in the mesophyll cells.
c) They fix carbon at night to minimize water loss.
d) They cannot survive in hot, dry environments.
Answer: c) They fix carbon at night to minimize water loss.
30. In C4 plants, the products of carbon fixation are transported to:
a) The chloroplasts of the mesophyll cells
b) The vacuole
c) The bundle sheath cells
d) The mitochondria
Answer: c) The bundle sheath cells
