- What is the primary pigment involved in photosynthesis?
a) Chlorophyll
b) Carotenoids
c) Xanthophyll
d) Anthocyanin
Answer: a) Chlorophyll - Where do light reactions of photosynthesis occur?
a) Mitochondria
b) Stroma
c) Thylakoid membrane
d) Cytoplasm
Answer: c) Thylakoid membrane - The splitting of water during the light reaction is called:
a) Photophosphorylation
b) Photolysis
c) Hydrolysis
d) Oxidation
Answer: b) Photolysis - Which molecule is the final electron acceptor in the light reactions?
a) NADP⁺
b) ATP
c) ADP
d) Oxygen
Answer: a) NADP⁺ - What is the primary product of the Calvin cycle?
a) Glucose
b) ATP
c) NADPH
d) G3P
Answer: d) G3P - Which enzyme is responsible for carbon fixation in the Calvin cycle?
a) ATP synthase
b) Rubisco
c) Hexokinase
d) Pyruvate kinase
Answer: b) Rubisco - What are the energy carriers produced in the light reactions?
a) ATP and NADPH
b) NADH and FADH₂
c) Glucose and ATP
d) Pyruvate and NADH
Answer: a) ATP and NADPH - What gas is released as a by-product during photosynthesis?
a) Carbon dioxide
b) Oxygen
c) Nitrogen
d) Methane
Answer: b) Oxygen - Which wavelength of light is least effective for photosynthesis?
a) Red
b) Blue
c) Green
d) Violet
Answer: c) Green - The Calvin cycle occurs in which part of the chloroplast?
a) Grana
b) Stroma
c) Thylakoid
d) Inner membrane
Answer: b) Stroma - What is the main purpose of light reactions?
a) Carbon fixation
b) Production of oxygen
c) Production of ATP and NADPH
d) Splitting glucose
Answer: c) Production of ATP and NADPH - The ATP formed in the light reaction is used for:
a) Glycolysis
b) Krebs cycle
c) Calvin cycle
d) Electron transport chain
Answer: c) Calvin cycle - Which process provides electrons for the light reactions?
a) Photolysis of water
b) Carbon fixation
c) ATP hydrolysis
d) Electron transport chain
Answer: a) Photolysis of water - C4 plants are more efficient than C3 plants in:
a) Hot, dry climates
b) Cold climates
c) Low light intensity
d) High moisture conditions
Answer: a) Hot, dry climates - Which of the following is NOT a product of the light-dependent reactions?
a) Oxygen
b) ATP
c) NADPH
d) Glucose
Answer: d) Glucose - The dark reactions are also called:
a) Krebs cycle
b) Calvin cycle
c) Light reactions
d) Glycolysis
Answer: b) Calvin cycle - The main source of carbon for the Calvin cycle is:
a) Glucose
b) Carbon dioxide
c) Methane
d) Oxygen
Answer: b) Carbon dioxide - Which molecule acts as the main energy currency in photosynthesis?
a) NADPH
b) ATP
c) G3P
d) FADH₂
Answer: b) ATP - What is the first stable product of carbon fixation in C3 plants?
a) Pyruvate
b) Phosphoglycerate (PGA)
c) Oxaloacetate
d) Malate
Answer: b) Phosphoglycerate (PGA) - CAM plants adapt to dry conditions by:
a) Fixing CO₂ during the night
b) Closing stomata during the day
c) Both a and b
d) Storing oxygen in vacuoles
Answer: c) Both a and b - What are the two stages of photosynthesis?
a) Glycolysis and Calvin cycle
b) Light and dark reactions
c) Krebs cycle and photolysis
d) Oxidation and reduction
Answer: b) Light and dark reactions - Chloroplasts are mainly found in which plant cells?
a) Root cells
b) Mesophyll cells
c) Epidermal cells
d) Guard cells
Answer: b) Mesophyll cells - Photorespiration occurs in the presence of:
a) High CO₂
b) Low O₂
c) High O₂
d) Low temperature
Answer: c) High O₂ - Which cycle is part of C4 photosynthesis?
a) Calvin cycle
b) Hatch-Slack pathway
c) Krebs cycle
d) Glycolysis
Answer: b) Hatch-Slack pathway - Which part of the chloroplast contains chlorophyll?
a) Outer membrane
b) Inner membrane
c) Thylakoid membrane
d) Stroma
Answer: c) Thylakoid membrane - The light-harvesting complexes are located in the:
a) Stroma
b) Thylakoid membrane
c) Cytoplasm
d) Outer membrane
Answer: b) Thylakoid membrane - What is the role of NADPH in the Calvin cycle?
a) It releases oxygen
b) It provides energy
c) It provides electrons
d) It fixes carbon
Answer: c) It provides electrons - C3 and C4 pathways differ mainly in:
a) Pigments used
b) Initial carbon fixation steps
c) Location of light reactions
d) Energy production
Answer: b) Initial carbon fixation steps - How many molecules of CO₂ are required to form one molecule of glucose?
a) 2
b) 4
c) 6
d) 8
Answer: c) 6 - Which of the following pigments absorbs blue and green light?
a) Chlorophyll a
b) Chlorophyll b
c) Carotenoids
d) Xanthophylls
Answer: c) Carotenoids
Home Biology Topics with MCQs Plant Physiology MCQs on “Photosynthesis: Light and Dark Reactions Explained”
MCQs on “Photosynthesis: Light and Dark Reactions Explained”
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