NEET UG - Photosynthesis in higher plants - light and dark reactions, photophosphorylation One Line Questions & Answers

1. What is the net number of ATP molecules required to fix one molecule of CO2 in the Calvin cycle? — 2

2. What is the net number of NADPH molecules required to fix one molecule of CO2 in the Calvin cycle? — 1

3. How many turns of the Calvin cycle are required to produce one molecule of glucose (a 6-carbon sugar)? — 6

4. The reduction of one molecule of CO2 in the Calvin cycle requires 2 molecules of ATP and 2 molecules of NADPH. How many molecules of CO2 need to be fixed to synthesize one molecule of glucose (C6H12O6)? — 6

5. When a molecule of CO2 is fixed by RuBisCO, what is the immediate product formed? — 3-phosphoglycerate

6. During the light-dependent reactions, the accumulation of protons inside the thylakoid lumen leads to: — A decrease in pH and an increase in the proton motive force.

7. Which of the following is the primary role of carotenoids in photosynthesis? — Dissipate excess light energy and protect chlorophyll from photodamage

8. The regeneration of Ribulose-1,5-bisphosphate (RuBP) in the Calvin cycle requires the input of which molecule? — ATP

9. Which of the following is NOT a product of the light-dependent reactions? — Glyceraldehyde-3-phosphate

10. The reduction phase of the Calvin cycle involves the conversion of 1,3-bisphosphoglycerate to glyceraldehyde-3-phosphate. This reaction is catalyzed by an enzyme that requires: — NADPH and ATP

11. Which enzyme catalyzes the initial fixation of carbon dioxide in the Calvin cycle? — RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase)

12. In C3 plants, the Calvin cycle occurs in which cells? — Mesophyll cells

13. The oxygen released during photosynthesis comes from the splitting of which molecule? — Water

14. The light-dependent reactions convert light energy into chemical energy in the form of ATP and NADPH. This process is also known as: — Photophosphorylation

15. What is the primary pigment involved in absorbing light energy during photosynthesis? — Chlorophyll a

16. Which of the following pigments acts as an accessory pigment, transferring absorbed light energy to the reaction center chlorophyll? — Chlorophyll b and carotenoids

17. Which of the following is a key difference between cyclic and non-cyclic photophosphorylation? — Non-cyclic photophosphorylation produces NADPH, while cyclic does not.

18. The reduction of 3-phosphoglycerate to glyceraldehyde-3-phosphate in the Calvin cycle requires energy from which molecule? — ATP and NADPH

19. What is the main product of the light-dependent reactions that is used in the Calvin cycle? — ATP and NADPH

20. In the Calvin cycle, the carboxylation of RuBP by RuBisCO leads to the formation of an unstable 6-carbon intermediate, which quickly breaks down into two molecules of: — 3-phosphoglycerate

21. Which of the following is NOT a condition that favors photorespiration? — High CO2 concentration

22. The process of photorespiration occurs when RuBisCO binds to oxygen instead of carbon dioxide. Which of the following is a consequence of photorespiration? — Wastage of energy and fixed carbon

23. What is the function of plastocyanin in the electron transport chain of photosynthesis? — It accepts electrons from Photosystem II and transfers them to Photosystem I.

24. What is the role of ferredoxin in the light-dependent reactions? — It carries electrons from Photosystem I to NADP+.

25. What is the fate of glyceraldehyde-3-phosphate (G3P) produced in the Calvin cycle? — It is used to regenerate RuBP and synthesize glucose and other organic molecules.

26. Which of the following best describes the role of NADP+ reductase? — It catalyzes the reduction of NADP+ to NADPH using electrons from ferredoxin.

27. Cyclic photophosphorylation involves only Photosystem I. What is the main product of cyclic photophosphorylation? — ATP

28. The energy for the regeneration of RuBP in the Calvin cycle is primarily supplied by: — ATP

29. For every three molecules of CO2 fixed in the Calvin cycle, how many molecules of G3P are exported from the cycle? — One

30. The chemiosmotic hypothesis explains ATP synthesis during photophosphorylation. It relies on the establishment of a proton gradient across which membrane? — Thylakoid membrane

31. What is the source of electrons that enter the electron transport chain during the light-dependent reactions? — Water

32. The light-independent reactions are directly dependent on the products of the light-dependent reactions. What are these products? — ATP and NADPH

33. What is the initial carbon dioxide acceptor molecule in the Calvin cycle? — Ribulose-1,5-bisphosphate (RuBP)

34. The enzyme ATP synthase utilizes the energy stored in the proton gradient to phosphorylate ADP to ATP. This process is known as: — Photophosphorylation

35. Which photosystem is primarily responsible for splitting water molecules? — Photosystem II

36. During non-cyclic photophosphorylation, electrons flow from water to NADP+. Which of the following is the final electron acceptor? — NADP+

37. Which component of the electron transport chain in the thylakoid membrane is responsible for pumping protons from the stroma into the thylakoid lumen? — Cytochrome b6f complex

38. The Z-scheme of photosynthesis describes the energy changes of electrons. Which photosystem has its reaction center chlorophyll absorbing light at a longer wavelength (700 nm)? — Photosystem I (PSI)

39. Which of the following is the correct order of electron flow in non-cyclic photophosphorylation? — Water -> PSII -> ETC -> PSI -> NADP+

40. The process of photophosphorylation involves the synthesis of ATP using light energy. Which enzyme is crucial for this process? — ATP synthase

41. In which part of the chloroplast does the light-dependent reaction of photosynthesis occur? — Thylakoid membrane

42. What is the primary sugar molecule produced by the Calvin cycle? — Glyceraldehyde-3-phosphate (G3P)

43. In the context of the Calvin cycle, what is meant by the term 'reduction'? — The conversion of 3-phosphoglycerate to glyceraldehyde-3-phosphate using ATP and NADPH.

44. The light-independent reactions, also known as the Calvin cycle, occur in which part of the chloroplast? — Stroma

45. The electron transport chain in the thylakoid membrane links Photosystem II and Photosystem I. What is the main function of this chain? — To pump protons and generate a proton gradient

46. What is the primary role of the antenna complex in photosystems? — To capture light energy and transfer it to the reaction center.

47. In cyclic photophosphorylation, where do the electrons return after passing through the electron transport chain? — To Photosystem I

48. What is the primary function of the Calvin cycle? — To fix atmospheric carbon dioxide into organic molecules

49. What is the role of NADP+ reductase in the light reactions? — To reduce NADP+ to NADPH

50. The light-independent reactions can occur in the absence of light, provided that the products of the light-dependent reactions are available. This statement is: — True, but they are indirectly dependent on light.

Photosynthesis in higher plants - light and dark reactions, photophosphorylation - One Line Questions