📌 BIOLOGY common questions about photosynthesis

1. What is the primary function of the light-dependent reactions in photosynthesis?
a) Production of glucose
b) Generation of ATP and NADPH
c) Absorption of carbon dioxide
d) Release of oxygen

2. Where do the light-dependent reactions take place in a plant cell?
a) Stroma
b) Thylakoid membrane
c) Cytoplasm
d) Nucleus

3. Which molecule is split during the light-dependent reactions to release oxygen?
a) Water
b) Carbon dioxide
c) Glucose
d) ATP

4. What is the role of photosystem II in the light-dependent reactions?
a) Production of NADPH
b) Absorption of light energy
c) Splitting water molecules
d) Release of oxygen

5. Which molecule acts as an electron carrier in the light-dependent reactions?
a) NADP+
b) ATP
c) Glucose
d) Carbon dioxide

6. What is the primary product of the light-independent reactions (Calvin cycle)?
a) Oxygen
b) Glucose
c) ATP
d) NADPH

7. In which part of the chloroplast does the Calvin cycle occur?
a) Thylakoid membrane
b) Stroma
c) Grana
d) Cytoplasm

8. What is the role of rubisco in the Calvin cycle?
a) Capture of light energy
b) Fixation of carbon dioxide
c) Production of ATP
d) Release of oxygen

9. How many molecules of G3P (glyceraldehyde-3-phosphate) are produced in one turn of the Calvin cycle?
a) 1
b) 2
c) 3
d) 6

10. What is the fate of most of the G3P molecules produced in the Calvin cycle?
a) Used to regenerate RuBP
b) Converted into glucose
c) Transferred to the light-dependent reactions
d) Released as waste products

11. Which molecule is responsible for providing the energy needed for the Calvin cycle?
a) ATP
b) NADPH
c) Water
d) Carbon dioxide

12. What is the role of the enzyme RuBisCO in the Calvin cycle?
a) Splitting water molecules
b) Regeneration of RuBP
c) Fixation of carbon dioxide
d) Production of glucose

13. During the light-independent reactions, what happens to the carbon atoms from carbon dioxide?
a) They are released as waste products
b) They are used to produce ATP
c) They are incorporated into organic molecules
d) They are converted into oxygen

14. Which molecule is regenerated at the end of the Calvin cycle to continue the process?
a) RuBP (ribulose bisphosphate)
b) G3P (glyceraldehyde-3-phosphate)
c) NADP+
d) ATP

15. What is the overall purpose of both the light-dependent and light-independent reactions in photosynthesis?
a) To produce oxygen for cellular respiration
b) To convert light energy into chemical energy (ATP and NADPH)
c) To release carbon dioxide into the atmosphere
d) To produce water as a byproduct

📍 Answer

1. b) Generation of ATP and NADPH

2. b) Thylakoid membrane

3.  a) Water

4. b) Absorption of light energy (and also c) Splitting water molecules)

5.  a) NADP+

6. b) Glucose

7.  b) Stroma

8.  b) Fixation of carbon dioxide

9.  a) 1 (Note: Two G3P molecules are needed to form one glucose, but one turn produces one G3P.)

10. a) Used to regenerate RuBP

11.  a) ATP (NADPH provides reducing power, but ATP provides energy.)

12.  c) Fixation of carbon dioxide

13. c) They are incorporated into organic molecules

14. a) RuBP (ribulose bisphosphate)

15.  b) To convert light energy into chemical energy (ATP and NADPH)

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