1. Photosynthesis mainly occurs in:
a) Roots
b) Stems
c) Leaves
d) Flowers
Answer: c) Leaves
Explanation: Leaves are the primary sites of photosynthesis due to chloroplast abundance.
2. Photosynthesis takes place in which cell organelle?
a) Mitochondria
b) Chloroplast
c) Golgi body
d) Ribosome
Answer: b) Chloroplast
Explanation: Chloroplast contains chlorophyll that captures light energy.
3. Which pigment is essential for photosynthesis?
a) Carotene
b) Xanthophyll
c) Chlorophyll
d) Anthocyanin
Answer: c) Chlorophyll
Explanation: Chlorophyll a is the primary pigment required for photosynthesis.
4. The general equation for photosynthesis is:
a) CO₂ + H₂O + Light → Glucose + O₂
b) O₂ + H₂O → Glucose + CO₂
c) Glucose + O₂ → Energy + CO₂
d) CO₂ + Glucose → O₂ + H₂O
Answer: a) CO₂ + H₂O + Light → Glucose + O₂
Explanation: Photosynthesis converts light energy into chemical energy.
5. Photosynthesis is an example of:
a) Catabolism
b) Anabolism
c) Respiration
d) Fermentation
Answer: b) Anabolism
Explanation: It is an anabolic process as simple molecules are built into glucose.
6. Who discovered that plants release oxygen during photosynthesis?
a) Robert Hooke
b) Joseph Priestley
c) Ingenhousz
d) Blackman
Answer: b) Joseph Priestley
Explanation: Priestley (1771) showed that plants release O₂ that supports burning/candle flame.
7. Who demonstrated that sunlight is essential for photosynthesis?
a) Priestley
b) Ingenhousz
c) Von Sachs
d) Blackman
Answer: b) Ingenhousz
Explanation: Ingenhousz proved that sunlight and green leaves are essential.
8. The law of limiting factors in photosynthesis was given by:
a) Calvin
b) Blackman
c) Hill
d) Ruben
Answer: b) Blackman
Explanation: Blackman’s law states that photosynthesis depends on the slowest factor.
9. Chlorophyll absorbs mainly:
a) Red and blue light
b) Green light
c) Yellow light
d) White light
Answer: a) Red and blue light
Explanation: Chlorophyll absorbs red & blue light, reflects green light.
10. Which pigment gives green color to leaves?
a) Xanthophyll
b) Chlorophyll
c) Carotene
d) Anthocyanin
Answer: b) Chlorophyll
Explanation: Chlorophyll reflects green wavelength.
11. Chlorophyll is located in:
a) Matrix of mitochondria
b) Thylakoid membrane of chloroplast
c) Cytoplasm
d) Cell wall
Answer: b) Thylakoid membrane of chloroplast
Explanation: Pigments are embedded in thylakoid membranes.
12. Which pigment is called the “primary photosynthetic pigment”?
a) Chlorophyll a
b) Chlorophyll b
c) Xanthophyll
d) Carotene
Answer: a) Chlorophyll a
Explanation: Chlorophyll a is essential for photosynthesis.
13. Which pigments are accessory pigments in photosynthesis?
a) Chlorophyll a
b) Chlorophyll b, carotenoids, xanthophylls
c) Anthocyanins
d) Hemoglobin
Answer: b) Chlorophyll b, carotenoids, xanthophylls
Explanation: Accessory pigments absorb additional wavelengths and transfer energy to chlorophyll a.
14. Hill reaction demonstrates:
a) Release of O₂ from water
b) Fixation of CO₂
c) ATP synthesis
d) Glucose formation
Answer: a) Release of O₂ from water
Explanation: Hill showed O₂ comes from splitting of water.
15. The splitting of water during photosynthesis is called:
a) Hydrolysis
b) Photolysis
c) Fermentation
d) Respiration
Answer: b) Photolysis
Explanation: Light energy splits water into O₂, electrons, and protons.
16. Who discovered photophosphorylation?
a) Hill
b) Arnon
c) Calvin
d) Blackman
Answer: b) Arnon
Explanation: Daniel Arnon discovered ATP formation via light-driven phosphorylation.
17. The oxygen released in photosynthesis comes from:
a) Carbon dioxide
b) Water
c) Glucose
d) Chlorophyll
Answer: b) Water
Explanation: Splitting of water (photolysis) releases O₂.
18. Photosynthetically active radiation (PAR) has wavelength range:
a) 100–400 nm
b) 400–700 nm
c) 700–1000 nm
d) 1000–1500 nm
Answer: b) 400–700 nm
Explanation: Visible light spectrum supports photosynthesis.
19. Chloroplasts are generally abundant in:
a) Root cortex
b) Leaf mesophyll cells
c) Stem epidermis
d) Xylem
Answer: b) Leaf mesophyll cells
Explanation: Palisade mesophyll cells contain numerous chloroplasts.
20. The site of light reaction is:
a) Stroma
b) Thylakoid membrane
c) Cytoplasm
d) Outer membrane of chloroplast
Answer: b) Thylakoid membrane
Explanation: Light-dependent reactions occur on thylakoid membranes.
21. The site of dark reaction is:
a) Thylakoid
b) Stroma of chloroplast
c) Mitochondria
d) Cytoplasm
Answer: b) Stroma of chloroplast
Explanation: Calvin cycle takes place in stroma.
22. Which is the first stable product of Calvin cycle?
a) Glucose
b) PGA (3-phosphoglyceric acid)
c) RuBP
d) NADPH
Answer: b) PGA (3-phosphoglyceric acid)
Explanation: CO₂ fixation produces 3-PGA as first stable compound.
23. The first CO₂ acceptor in Calvin cycle is:
a) PEP
b) RuBP
c) PGA
d) Malate
Answer: b) RuBP
Explanation: Ribulose-1,5-bisphosphate combines with CO₂.
24. Which enzyme fixes CO₂ in Calvin cycle?
a) PEP carboxylase
b) RuBisCO
c) ATP synthase
d) NADP reductase
Answer: b) RuBisCO
Explanation: RuBisCO catalyzes CO₂ fixation with RuBP.
25. The strongest biological oxidizing agent in photosynthesis is:
a) NADP⁺
b) Water
c) Mn²⁺
d) P680⁺
Answer: d) P680⁺
Explanation: P680⁺ in photosystem II extracts electrons from water.
26. Light reaction of photosynthesis occurs in:
a) Stroma
b) Thylakoid membrane
c) Cytoplasm
d) Matrix of mitochondria
Answer: b) Thylakoid membrane
Explanation: Light reactions take place on thylakoid membranes where pigments are located.
27. The light reaction produces:
a) Glucose and CO₂
b) ATP, NADPH, O₂
c) RuBP and glucose
d) Pyruvate and NADH
Answer: b) ATP, NADPH, O₂
Explanation: Light-dependent reactions generate ATP, NADPH, and release O₂ from water.
28. The two photosystems involved in light reactions are:
a) PSI and PSII
b) PSII and PEP
c) RuBP and PGA
d) ATP and NADPH
Answer: a) PSI and PSII
Explanation: Photosystem I (P700) and Photosystem II (P680) work together.
29. The reaction center of Photosystem II has:
a) P700
b) P680
c) P600
d) P500
Answer: b) P680
Explanation: PSII has a special chlorophyll a molecule absorbing light at 680 nm.
30. The reaction center of Photosystem I has:
a) P680
b) P700
c) P600
d) P720
Answer: b) P700
Explanation: PSI has a special chlorophyll a molecule absorbing at 700 nm.
31. Photolysis of water takes place in:
a) Photosystem I
b) Photosystem II
c) Stroma
d) Cytoplasm
Answer: b) Photosystem II
Explanation: Splitting of water into O₂, protons, and electrons occurs at PSII.
32. The oxygen released in photosynthesis comes from:a) Carbon dioxide
b) Water
c) Chlorophyll
d) Glucose
Answer: b) Water
Explanation: Splitting of water (photolysis) produces oxygen.
33. The process of ATP synthesis during photosynthesis is called:
a) Oxidative phosphorylation
b) Photophosphorylation
c) Substrate-level phosphorylation
d) Chemiosmosis only
Answer: b) Photophosphorylation
Explanation: ATP is formed from ADP and Pi using light energy.
34. Non-cyclic photophosphorylation involves:
a) Only PSI
b) Only PSII
c) Both PSI and PSII
d) No photosystem
Answer: c) Both PSI and PSII
Explanation: Electrons move from PSII → PSI → NADPH in non-cyclic flow.
35. Cyclic photophosphorylation involves:
a) Only PSI
b) Only PSII
c) Both PSI and PSII
d) RuBisCO
Answer: a) Only PSI
Explanation: Electrons cycle back to PSI, producing ATP only.
36. Which of the following is not produced in cyclic photophosphorylation?
a) ATP
b) NADPH
c) Proton gradient
d) Electron flow
Answer: b) NADPH
Explanation: Cyclic flow generates ATP but no NADPH or O₂.
37. The electron acceptor in Photosystem II is:
a) Plastoquinone
b) NADP⁺
c) Ferredoxin
d) Plastocyanin
Answer: a) Plastoquinone
Explanation: Electrons from PSII are transferred to plastoquinone.
38. The electron acceptor in Photosystem I is:
a) Plastoquinone
b) Ferredoxin
c) NADPH
d) ATP
Answer: b) Ferredoxin
Explanation: PSI passes electrons to ferredoxin before NADP⁺ reduction.
39. NADPH is finally formed by the action of:
a) ATP synthase
b) NADP reductase
c) Ferredoxin
d) Plastoquinone
Answer: b) NADP reductase
Explanation: NADP reductase reduces NADP⁺ to NADPH using electrons.
40. Proton gradient in photosynthesis is generated in:
a) Cytoplasm
b) Thylakoid lumen
c) Stroma
d) Nucleus
Answer: b) Thylakoid lumen
Explanation: Protons accumulate inside thylakoid lumen, driving ATP synthesis.
41. The enzyme that synthesizes ATP in photosynthesis is:
a) ATP synthase
b) RuBisCO
c) NADP reductase
d) Kinase
Answer: a) ATP synthase
Explanation: ATP synthase uses proton gradient to form ATP.
42. The process of ATP synthesis by proton gradient across thylakoid membrane is called:
a) Oxidation
b) Photolysis
c) Chemiosmosis
d) Fermentation
Answer: c) Chemiosmosis
Explanation: Chemiosmosis is the mechanism behind photophosphorylation.
43. The immediate source of energy for ATP synthesis in chloroplast is:
a) Sunlight directly
b) Proton gradient
c) Water splitting
d) CO₂ fixation
Answer: b) Proton gradient
Explanation: Proton motive force drives ATP synthase.
44. In non-cyclic photophosphorylation, the flow of electrons is:
a) PSI → PSII
b) PSII → PSI → NADP⁺
c) PSI → Ferredoxin → PSII
d) PSII → Ferredoxin only
Answer: b) PSII → PSI → NADP⁺
Explanation: Electrons move linearly to form NADPH.
45. The main function of cyclic photophosphorylation is to:
a) Produce NADPH
b) Produce ATP
c) Produce O₂
d) Fix CO₂
Answer: b) Produce ATP
Explanation: Cyclic electron flow generates only ATP.
46. In non-cyclic photophosphorylation, electrons lost by PSII are replaced by:
a) Electrons from PSI
b) Water (photolysis)
c) NADPH
d) RuBP
Answer: b) Water (photolysis)
Explanation: Water splitting replenishes electrons in PSII.
47. In cyclic photophosphorylation, the final electron acceptor is:
a) NADP⁺
b) Ferredoxin
c) P700 (PSI reaction center)
d) O₂
Answer: c) P700 (PSI reaction center)
Explanation: Electrons return to PSI reaction center.
48. ATP and NADPH formed in light reaction are used in:
a) Photorespiration
b) Calvin cycle (dark reaction)
c) Glycolysis
d) Krebs cycle
Answer: b) Calvin cycle (dark reaction)
Explanation: ATP and NADPH drive CO₂ fixation in Calvin cycle.
49. The “Z-scheme” of photosynthesis refers to:
a) Calvin cycle
b) Electron transport chain in light reaction
c) Photorespiration pathway
d) Cyclic phosphorylation
Answer: b) Electron transport chain in light reaction
Explanation: Z-scheme describes electron flow from PSII → PSI → NADPH.
50. In photophosphorylation, the final hydrogen acceptor is:
a) Water
b) Oxygen
c) NADP⁺
d) ATP
Answer: c) NADP⁺
Explanation: NADP⁺ accepts electrons and H⁺ to form NADPH.
51. Dark reaction of photosynthesis takes place in:
a) Thylakoid lumen
b) Cytoplasm
c) Stroma of chloroplast
d) Outer membrane
Answer: c) Stroma of chloroplast
Explanation: Enzymes for CO₂ fixation (Calvin cycle) are present in stroma.
52. The dark reaction is also known as:
a) Light reaction
b) Carbon fixation reaction
c) Photolysis
d) Electron transport
Answer: b) Carbon fixation reaction
Explanation: It fixes CO₂ into carbohydrates using ATP and NADPH.
53. The enzyme responsible for CO₂ fixation in Calvin cycle is:
a) PEP carboxylase
b) RuBisCO
c) ATP synthase
d) NADP reductase
Answer: b) RuBisCO
Explanation: Ribulose bisphosphate carboxylase/oxygenase (RuBisCO) fixes CO₂ with RuBP.
54. The first CO₂ acceptor in Calvin cycle is:
a) RuBP
b) PGA
c) PEP
d) Malate
Answer: a) RuBP
Explanation: Ribulose-1,5-bisphosphate combines with CO₂ to form 3-PGA.
55. The first stable product of Calvin cycle is:
a) RuBP
b) 3-PGA (phosphoglyceric acid)
c) Glucose
d) Malate
Answer: b) 3-PGA (phosphoglyceric acid)
Explanation: CO₂ fixation forms 3-PGA as the first stable compound.
56. How many molecules of CO₂ are required to synthesize one molecule of glucose in Calvin cycle?
a) 2
b) 4
c) 6
d) 12
Answer: c) 6
Explanation: Fixation of 6 CO₂ produces one glucose molecule.
57. The Calvin cycle is also called:
a) C₄ pathway
b) C₃ pathway
c) CAM pathway
d) Z-scheme
Answer: b) C₃ pathway
Explanation: First stable product is a 3-carbon compound (3-PGA).
58. Who discovered the Calvin cycle?
a) Blackman
b) Calvin, Benson, and Bassham
c) Arnon
d) Hill
Answer: b) Calvin, Benson, and Bassham
Explanation: Melvin Calvin and team traced CO₂ fixation pathway using radioactive carbon.
59. The number of ATP and NADPH required for one glucose in Calvin cycle is:
a) 6 ATP + 6 NADPH
b) 12 ATP + 12 NADPH
c) 18 ATP + 12 NADPH
d) 30 ATP + 20 NADPH
Answer: c) 18 ATP + 12 NADPH
Explanation: Energy and reducing power are required to fix 6 CO₂ into one glucose.
60. The main limitation of RuBisCO enzyme is:
a) Works only in dark
b) Acts as both carboxylase and oxygenase
c) Requires high temperature
d) Requires light directly
Answer: b) Acts as both carboxylase and oxygenase
Explanation: RuBisCO fixes O₂ also, leading to photorespiration.
61. In photorespiration, the wasteful product is:
a) Oxygen
b) Ammonia
c) CO₂
d) Glucose
Answer: c) CO₂
Explanation: Photorespiration results in loss of CO₂ and energy.
62. C₄ plants minimize photorespiration by:
a) Having Kranz anatomy and PEP carboxylase
b) Using only RuBisCO
c) Performing photosynthesis at night only
d) Absorbing less CO₂
Answer: a) Having Kranz anatomy and PEP carboxylase
Explanation: C₄ plants concentrate CO₂ around RuBisCO to avoid oxygenase activity.
63. The first stable product in C₄ pathway is:
a) 3-PGA
b) Malate (or oxaloacetate)
c) Glucose
d) RuBP
Answer: b) Malate (or oxaloacetate)
Explanation: CO₂ combines with PEP to form oxaloacetate (4C compound).
64. The primary CO₂ acceptor in C₄ plants is:
a) RuBP
b) PEP (phosphoenol pyruvate)
c) PGA
d) Malate
Answer: b) PEP (phosphoenol pyruvate)
Explanation: PEP carboxylase fixes CO₂ to form oxaloacetate.
65. Kranz anatomy is characteristic of:
a) C₃ plants
b) C₄ plants
c) CAM plants
d) Algae
Answer: b) C₄ plants
Explanation: C₄ plants have bundle sheath cells arranged around vascular bundles.
66. In C₄ plants, the Calvin cycle occurs in:
a) Mesophyll cells
b) Bundle sheath cells
c) Guard cells
d) Epidermal cells
Answer: b) Bundle sheath cells
Explanation: CO₂ is concentrated in bundle sheath cells where Calvin cycle takes place.
67. The advantage of C₄ plants over C₃ plants is:
a) Lower water requirement and reduced photorespiration
b) Faster growth only in shade
c) Less ATP requirement
d) Absence of RuBisCO
Answer: a) Lower water requirement and reduced photorespiration
Explanation: C₄ plants are more efficient under high light, temperature, and dry conditions.
68. The first stable product of CAM pathway is:
a) 3-PGA
b) Malate
c) RuBP
d) Fructose
Answer: b) Malate
Explanation: CAM plants store CO₂ at night as malic acid (malate).
69. In CAM plants, CO₂ fixation occurs:
a) Day only
b) Night only
c) Day and night, but temporally separated
d) In roots only
Answer: c) Day and night, but temporally separated
Explanation: CAM plants fix CO₂ at night (as malate) and use it during day.
70. CAM plants are adapted to:
a) Cold regions
b) Deserts and arid conditions
c) Rainforests
d) Aquatic environment
Answer: b) Deserts and arid conditions
Explanation: CAM photosynthesis minimizes water loss.
71. Example of C₄ plants is:
a) Wheat and rice
b) Maize and sugarcane
c) Mango and banana
d) Beans and peas
Answer: b) Maize and sugarcane
Explanation: These are classic C₄ plants with Kranz anatomy.
72. Example of CAM plants is:
a) Rice and wheat
b) Maize and sorghum
c) Pineapple and cactus
d) Mustard and pea
Answer: c) Pineapple and cactus
Explanation: CAM plants survive in deserts by fixing CO₂ at night.
73. In C₄ cycle, decarboxylation of malate occurs in:
a) Mesophyll cells
b) Bundle sheath cells
c) Guard cells
d) Epidermal cells
Answer: b) Bundle sheath cells
Explanation: Malate releases CO₂ in bundle sheath cells for Calvin cycle.
74. Photorespiration is more common in:
a) C₃ plants
b) C₄ plants
c) CAM plants
d) Algae only
Answer: a) C₃ plants
Explanation: C₃ plants lack CO₂ concentrating mechanism, hence higher photorespiration.
75. CAM pathway helps plants by:
a) Fixing CO₂ at night and reducing water loss
b) Increasing photorespiration
c) Avoiding ATP use
d) Producing oxygen at night
Answer: a) Fixing CO₂ at night and reducing water loss
Explanation: CAM plants conserve water by closing stomata during day.
76. Which element is essential for the photolysis of water in photosynthesis?
a) Iron
b) Magnesium
c) Manganese
d) Potassium
Answer: c) Manganese
Explanation: Manganese is part of the oxygen-evolving complex of PSII required for water splitting.
77. The Z-scheme in photosynthesis represents:
a) Calvin cycle
b) Cyclic photophosphorylation
c) Electron transport chain in light reaction
d) CAM pathway
Answer: c) Electron transport chain in light reaction
Explanation: It shows electron flow from PSII → PSI → NADP⁺.
78. Which part of the chloroplast contains the enzymes of Calvin cycle?
a) Grana
b) Stroma
c) Thylakoid lumen
d) Cristae
Answer: b) Stroma
Explanation: Calvin cycle enzymes are located in the stroma.
79. The primary function of light reaction is to:
a) Fix carbon dioxide
b) Produce ATP and NADPH
c) Break down glucose
d) Release CO₂
Answer: b) Produce ATP and NADPH
Explanation: These products power the dark reaction.
80. Which of the following organisms first released oxygen into Earth’s atmosphere?
a) Algae
b) Cyanobacteria
c) Ferns
d) Fungi
Answer: b) Cyanobacteria
Explanation: Oxygenic photosynthesis by cyanobacteria enriched Earth’s atmosphere with O₂.
81. What is the full form of RuBisCO?
a) Ribulose-1,5-bisphosphate carboxylase oxygenase
b) Ribose bisphosphate carboxylase oxidase
c) Ribulose-5-phosphate carbon oxidase
d) Ribose-5-carboxylase oxygenase
Answer: a) Ribulose-1,5-bisphosphate carboxylase oxygenase
Explanation: RuBisCO fixes CO₂ with RuBP, also has oxygenase activity.
82. The net gain of glucose from the Calvin cycle requires:
a) 6 CO₂, 12 ATP, 12 NADPH
b) 6 CO₂, 18 ATP, 12 NADPH
c) 12 CO₂, 18 ATP, 6 NADPH
d) 12 CO₂, 12 ATP, 12 NADPH
Answer: b) 6 CO₂, 18 ATP, 12 NADPH
Explanation: This energy input is needed to synthesize one glucose molecule.
83. Which scientist used radioactive carbon (¹⁴C) to trace carbon fixation in photosynthesis?
a) Blackman
b) Hill
c) Calvin
d) Arnon
Answer: c) Calvin
Explanation: Melvin Calvin’s ¹⁴C tracer experiments mapped the Calvin cycle.
84. In the light reaction, protons accumulate in:
a) Stroma
b) Thylakoid lumen
c) Cytoplasm
d) Nucleus
Answer: b) Thylakoid lumen
Explanation: Proton gradient across thylakoid drives ATP synthase.
85. C₄ plants are better adapted to:
a) Cold and shaded conditions
b) High light intensity, high temperature, low CO₂
c) Low light, low temperature, high CO₂
d) Desert night photosynthesis
Answer: b) High light intensity, high temperature, low CO₂
Explanation: C₄ photosynthesis minimizes photorespiration under such conditions.
86. CAM plants open their stomata during:
a) Day only
b) Night only
c) Day and night
d) Never
Answer: b) Night only
Explanation: CAM plants fix CO₂ at night to minimize water loss.
87. The pigment system of photosynthesis was first demonstrated by:
a) Hill
b) Emerson
c) Calvin
d) Blackman
Answer: b) Emerson
Explanation: Emerson and Arnold showed photosynthesis needs two photosystems (Emerson effect).
88. The absorption spectrum of chlorophyll matches closely with:
a) Respiration spectrum
b) Action spectrum of photosynthesis
c) Reflection spectrum
d) Calvin cycle
Answer: b) Action spectrum of photosynthesis
Explanation: The action spectrum shows effectiveness of different wavelengths in photosynthesis.
89. The red drop (Emerson effect) refers to:
a) Drop in photosynthesis beyond 680 nm light
b) Increase in photosynthesis beyond 700 nm
c) Drop in respiration rate
d) Drop in chlorophyll content
Answer: a) Drop in photosynthesis beyond 680 nm light
Explanation: Photosynthesis rate drops in far-red light unless both PSII and PSI work together.
90. Which gas is essential for photosynthesis?
a) Oxygen
b) Nitrogen
c) Carbon dioxide
d) Hydrogen
Answer: c) Carbon dioxide
Explanation: CO₂ is fixed into carbohydrates.
91. The ATP–NADPH ratio from cyclic photophosphorylation is:
a) 1:1
b) 2:1
c) 3:2
d) Only ATP, no NADPH
Answer: d) Only ATP, no NADPH
Explanation: Cyclic flow produces ATP only.
92. The “quantasome” is:
a) Functional unit of photosynthesis in thylakoid membrane
b) Functional unit of mitochondria
c) Part of Calvin cycle
d) ATP–NADPH pump
Answer: a) Functional unit of photosynthesis in thylakoid membrane
Explanation: Quantasomes contain pigment–protein complexes in photosystems.
93. How many photons of light are required (minimum) to evolve one molecule of O₂ in photosynthesis?
a) 2
b) 4
c) 6
d) 8
Answer: d) 8
Explanation: At least 8 photons (4 each for PSII and PSI) are required per O₂ molecule.
94. In C₃ plants, the first stable product of CO₂ fixation is:
a) 3-PGA
b) Oxaloacetate
c) Malate
d) Glucose
Answer: a) 3-PGA
Explanation: Hence Calvin cycle is called the C₃ pathway.
95. In C₄ plants, the Calvin cycle takes place in:
a) Mesophyll cells
b) Bundle sheath cells
c) Guard cells
d) Root cells
Answer: b) Bundle sheath cells
Explanation: CO₂ is concentrated in bundle sheath cells for Calvin cycle.
96. In CAM plants, CO₂ fixation at night occurs by:
a) RuBisCO
b) PEP carboxylase
c) ATP synthase
d) Ferredoxin
Answer: b) PEP carboxylase
Explanation: CAM plants use PEP carboxylase at night to form malate.
97. The first stable product of CAM pathway is:
a) 3-PGA
b) Malate
c) RuBP
d) Sucrose
Answer: b) Malate
Explanation: Malate is stored in vacuoles at night.
98. Which of the following is a C₄ plant?
a) Wheat
b) Maize
c) Rice
d) Potato
Answer: b) Maize
Explanation: Maize has Kranz anatomy and follows the C₄ cycle.
99. Which of the following is a CAM plant?
a) Sugarcane
b) Wheat
c) Pineapple
d) Barley
Answer: c) Pineapple
Explanation: Pineapple uses CAM photosynthesis to conserve water.
100. The overall efficiency of energy conversion in photosynthesis is approximately:
a) 1–2%
b) 5–8%
c) 10–12%
d) 20–25%
Answer: a) 1–2%
Explanation: Despite capturing sunlight, actual conversion efficiency is about 1–2%.