250+ TOP MCQs on Energy Production by Photosynthesis and Answers

Microbiology Multiple Choice Questions on “Energy Production by Photosynthesis”.

1. Which of the following acts as a chemical reductant in bacterial photosynthesis?
A. oxygen
B. water
C. hydrogen sulphide
D. ammonia
Answer: C
Clarification: Bacteria that performs photosynthesis utilises inorganic compound H₂S or organic compounds as chemical reductant instead of water.

2. The region in which bacteriochlorophyll can absorb light is _________
A. ultraviolet region
B. infrared region
C. visible region
D. microwave region
Answer: B
Clarification: Anoxygenic photosynthetic bacteria possess bacteriochlorophyll which absorbs light in the infrared region (725 to 1035 nm).

3. Where are bacteriochlorophyll present in the cell?
A. chloroplast
B. cytoplasm
C. mitochondria
D. membrane
Answer: D
Clarification: Bacteriochlorophyll are not contained in the chloroplasts but are found in extensive membrane systems like the cytoplasmic membrane throughout the bacterial cell.

4. Which of the following steps during electron transfer in anoxygenic photosynthesis is the ATP production step?
A. Ferredoxin to ubiquinone
B. ubiquinone to cyt b
C. cyt b to cyt f
D. cyt f to excited bacteriochlorophyll
Answer: C
Clarification: The energy released in electron transfer between cytochrome b and cytochrome f is used for photophosphorylation i.e., the generation of ATP from ADP and inorganic phosphate.

5. An essential process connected with photosynthesis is?
A. photolysis
B. synthesis of glucose
C. photophosphorylation
D. electron transfer
Answer: A
Clarification: In cyclic photophosphorylation electron lost by pigment system II is not cycled back instead they are replaced by the light-generated breakdown of water, called photolysis.

6. Purple Sulphur Bacteria contains bacteriochlorophyll b and bacteriochlorophyll c.
A. True
B. False
Answer: B
Clarification: Purple Sulphur bacteria contains bacteriochlorophyll a and bacteriochlorophyll b and it utilizes sulphur containing compound as chemical reductant.

7. Chlorobium sp. is which type of bacteria?
A. Purple Sulphur Bacteria
B. Purple Non-sulphur Bacteria
C. Green Sulphur bacteria
D. Green Non-sulphur bacteria
Answer: C
Clarification: Chlorobium sp. is a Green sulphur bacteria that contain bacteriochlorophyll c and d and utilizes sulphur as a chemical reductant in photosynthesis.

8. RuBisCO enzyme plays an important role in __________
A. light phase
B. dark phase
C. electron transport chain
D. TCA cycle
Answer: B
Clarification: All the enzymatic reactions take place in the dark phase which does not depend on light. RuBisCO helps in the reaction between RuBP and carbon dioxide to form 3-phosphoglycerate.

9. The final product of Calvin cycle is _________
A. RuBP
B. Glucose
C. Dihydroxy acetone phosphate
D. Glyceraldehyde-3-phosphate
Answer: D
Clarification: Glyceraldehyde-3-phosphate is the final product of the Calvin cycle which again regenerates RuBP.

10. The dark reaction in photosynthesis is governed by __________
A. CO₂, temperature, and light
B. CO₂, light, and water
C. water, temperature, and CO₂
D. oxygen, water, and temperature
Answer: A
Clarification: The dark reaction does not require light and involves the reduction of carbon dioxide to yield glyeraldehyde-3-phosphate.

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