Photosynthesis Multiple Choice Questions MCQs with Answers

1. In photosynthesis; the light-independent reactions take place at:
a. Stromal matrix
b. Thylakoid lumen
c. Photosystem I
d. Photosystem II
Answer: a. Stromal matrix

2. The aldehyde which is formed during the photosynthesis of plants is:
a. Methanal
b. Acetaldehyde
c. Propanal
d. Ethanal
Answer: a. Methanal

3. About 80% of the photosynthesis that takes place on this earth is carried out by:
a. Trees
b. Algae present in freshwater
c. Algae present in ocean water
d. Herbs
Answer: c. Algae present in ocean water

4. Oxygen which is liberated during photosynthesis comes from:
a. Carbon dioxide
b. Water
c. Chlorophyll
d. Glucose
Answer: b. Water

5. The process in which light energy is converted to chemical energy is known as:
a. Digestive action
b. Respiration
c. Photosynthesis
d. Fermentation
Answer: c. Photosynthesis

6. Dark reaction in photosynthesis is called so because:
a. It can only occur in dark
b. It does not require direct light
c. It cannot occur during daytime
d. None of these
Answer: b. It does not require direct light

7. During photosynthesis the oxygen in glucose comes from…?
a. Water
b. Carbon dioxide
c. O2 in air
d. Both from water and CO2
Answer: b. Carbon dioxide

Recommended: Photosynthesis Practice Test

8. The law of limiting factor for photosynthesis was given by: Hint: The year 1905.
a. Ruben
b. Krebs
c. Calvin
d. Blackman
Answer: d. Blackman

9. The percentage of light energy utilized by the higher plants in the process of photosynthesis is:
a. 100%
b. 10 to 20%
c. 50%
d. 1 to 2%
Answer: d. 1 to 2%

10. The catalyst in photosynthesis is…?
a. Sunlight
b. Red light
c. Water
d. Chlorophyll
Answer: d. Chlorophyll

11. If the Carbon dioxide content of the atmosphere is as high as 300 parts per million; then:
a. All plant would be killed
b. The plant not glow properly
c. The plants will grow for sometimes and then die
d. The plants would thrive well
Answer: d. The plants would thrive well

12. The dye used by Robert Hill for his famous Hill-reaction:
a. Dichlorophenol indophenol (DCPIP)
b. Sulphur green
c. Methylene blue
d. Eosin
Answer: a. Dichlorophenol indophenol (DCPIP)

13. The part of carbon dioxide in the dark reactions of photosynthesis was successfully traced by the use of which of the following?
a. O18
b. C14
c. P32
d. X-rays
Answer: b. C14

14. Discovery of the Emerson effect has already shown the existence of…?
a. Two distinct photochemical reactions or processes
b. Light and dark reactions of photosynthesis
c. Photophosphorylation
d. Photorespiration
Answer: a. Two distinct photochemical reactions or processes

15. What is the percentage of absorbed water is used during photosynthesis?
a. 50%
b. 90%
c. 1%
d. 25%
Answer: c. 1%

16. Maximum photosynthesis occurs in…?
a. Blue light
b. Green light
c. Red light
d. None of these
Answer: c. Red light

17. Oxygenic photosynthesis occurs in…?
a. Chromatium
b. Oscilatoria
c. Rhodospirillum
d. Chlorobium
Answer: b. Oscilatoria

18. The optimum temperature range for photosynthesis is:
a. 25-45 C
b. 10-15 C
c. 35-50 C
d. 20-35 C
Answer: d. 20-35 C

19. Reduction of NAD^(+) does not occur in which of the following reaction?
a. Pyruvic acid → Acetyl CoA
b. Isocitric acid → α-ketogulatric acid
c. Malic acid → Oxaloacetic acid
d. Succinic acid → Fumaric acid
Answer: d. Succinic acid → Fumaric acid

20. Kranz anatomy is found in the leaves of:
a. C4 plants
b. Both C3 and C4 plants
c. C3 plants
d. All of these
Answer: a. C4 plants

21. In which type of reactions related to plant photosynthesis, peroxisomes are involved?
a. Glycolate cycle
b. Calvin cycle
c. Glyoxylate cycle
d. Bacterial photosynthesis
Answer: a. Glycolate cycle

22. Photorespiration involves oxidation of…?
a. PGA
b. RuBP
c. Chlorophyll a
d. None of these
Answer: b. RuBP

23. A molecule of glucose is formed in the Calvin cycle from:
a. 6CO2 + 30ATP + 12NADPH
b. 6CO2 + 12ATP
c. 6CO2 + 18ATP + 12NADPH
d. 6CO2 + 18ATP + 30NADPH
Answer: c. 6CO2 + 18ATP + 12NADPH

24. Electrons from excited chlorophyll molecules of photosystem-II are accepted first by the:
a. Pheophytin
b. Ferredoxin
c. Cytochrome f
d. Cytochrome b
Answer: a. Pheophytin

25. Which of the following is inhibited by DCMU?
a. PS-I
b. PS-II
c. Oxidative phosphorylation
d. Destroys chloroplast
Answer: b. PS-II

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