NEET 2025 Biology Model Questions with Answers

A photosystem is a protein-pigment complex found in the thylakoid membranes of plants, algae, and cyanobacteria, essential for photosynthesis. It captures light energy and converts it into chemical energy. Each photosystem consists of two main parts: the antenna complex, which gathers light energy, and the reaction center, where photochemistry occurs. There are two types: photosystem I (PSI) and photosystem II (PSII). PSII splits water into oxygen, protons, and electrons, while PSI boosts electrons’ energy to form NADPH. Together, they drive the light-dependent reactions of photosynthesis, enabling the production of ATP and NADPH for use in the Calvin cycle. This is an MCQ on Photosystems with Answers (NEET 2025 Biology Model Questions with Answers).

Plant Physiology Notes | Plant Physiology MCQs | Plant Physiology PPTs

1. Where are photosystems located in plants?

a) Cytoplasm
b) Stroma
c) Thylakoid membranes
d) Mitochondria

2. Which type of light does photosystem II (PSII) primarily absorb?

a) Blue light
b) Far-red light
c) Red light
d) Ultraviolet light3.

3. What is the main function of PSII in photosynthesis?

a) Producing NADPH directly
b) Splitting water into oxygen and protons
c) Capturing light energy
d) Synthesizing ATP

4. What are the two main components of a photosystem?

a) ATP and NADPH
b) Antenna complex and reaction center
c) Chloroplast and mitochondria
d) Proton pump and electron carriers

5. Which pigment is at the core of PSII?

a) P680
b) P700
c) Chlorophyll b
d) Carotenoids

6. What type of electron acceptors are used by type I photosystems?

a) Quinones
b) Ferredoxin-like iron-sulfur clusters
c) Cytochrome c
d) ATP

7. Which photosystem is involved in creating oxygen as a byproduct?

a) Photosystem I
b) Photosystem II
c) Both PSI and PSII
d) Neither PSI nor PSII

8. How many light-harvesting complexes (LHCII) are typically associated with each PSII?

a) 4
b) 6
c) 8
d) 10

9. What mechanism helps funnel light energy to the reaction center in a photosystem?

a) Proton pumping
b) Resonance energy transfer
c) ATP synthesis
d) Cyclic electron flow

10. What is the role of P700 in photosystem I?

a) Splitting water
b) Exciting electrons with light energy
c) Pumping protons
d) Synthesizing glucose

11. What is the end product of the electron transfer in photosystem I?

a) NADPH
b) ATP
c) Oxygen
d) Glucose

12. What happens during cyclic photophosphorylation?

a) Electrons move through PSI and return to the same system
b) Electrons move from PSII to PSI without cycling
c) Water is split into oxygen and protons
d) ATP and NADPH are formed simultaneously

13. What protects photosystems from damage caused by excess light?

a) Formation of reactive oxygen species
b) Heat release and antioxidants
c) Increased ATP synthesis
d) Proton gradient dissipation

14. Which part of the PSII reaction center is primarily affected by light damage?

a) P680 chlorophyll molecule
b) D1 subunit
c) Oxygen-evolving complex
d) Antenna complex

15. What replaces damaged D1 subunits in PSII?

a) ATP synthase
b) Newly synthesized D1 subunits
c) Ferredoxin
d) Reactive oxygen species

Answer Key:

1. c) Thylakoid membranes
2. c) Red light
3. b) Splitting water into oxygen and protons
4. b) Antenna complex and reaction center
5. a) P680

6. b) Ferredoxin-like iron-sulfur clusters
7. b) Photosystem II
8. c) 8
9. b) Resonance energy transfer
10. b) Exciting electrons with light energy

11. a) NADPH
12. a) Electrons move through PSI and return to the same system
13. b) Heat release and antioxidants
14. b) D1 subunit
15. b) Newly synthesized D1 subunits

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