Understanding Light Reaction and Dark Reaction Differences
Light reaction and dark reaction are two crucial stages of photosynthesis in plants. Both processes contribute to the production of energy, but they differ in terms of their occurrence, requirements, and products.
The light reaction, also known as the light-dependent reaction, occurs in the thylakoid membranes of chloroplasts. It requires sunlight to produce ATP and NADPH, which are essential for the next phase of photosynthesis.
The dark reaction, also called the light-independent reaction or Calvin cycle, occurs in the stroma of the chloroplast. It does not require direct sunlight but relies on ATP and NADPH from the light reaction to synthesize glucose from carbon dioxide.
Differences Between Light Reaction and Dark Reaction
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FAQs on Difference Between Light Reaction and Dark Reaction
1. What is the difference between light reaction and dark reaction in simple terms?
The light reaction converts sunlight into ATP and NADPH, while the dark reaction uses these molecules to make glucose from CO₂.
2. What is the connection between light reaction and dark reaction?
The light reaction provides ATP and NADPH needed for the dark reaction to synthesize glucose.
3. What are light reactions and dark reactions also known as?
Light reactions are also called light-dependent reactions, and dark reactions are known as the Calvin cycle or light-independent reactions.
4. What is the difference between PS1 and PS2?
Photosystem I (PSI) primarily helps in producing NADPH, while Photosystem II (PSII) helps in ATP production and splitting water molecules.
5. What is the Z scheme of the light reaction?
The Z scheme describes the flow of electrons in light reactions, showing the movement from Photosystem II to Photosystem I.
6. What is the full form of NADPH?
NADPH stands for Nicotinamide Adenine Dinucleotide Phosphate (reduced form).
7. What are P680 and P700?
P680 and P700 are special chlorophyll molecules in Photosystem II and Photosystem I, respectively, that absorb light energy.
8. What is another name for the Calvin cycle?
The Calvin cycle is also called the C3 cycle.
9. What is the difference between ATP and NADPH?
ATP is an energy carrier, while NADPH is an electron donor in photosynthesis.
10. Why is photorespiration a wasteful process?
Photorespiration reduces photosynthetic efficiency by consuming oxygen and releasing CO₂ without producing glucose.
11. What is a stack of thylakoids called?
A stack of thylakoids is called a granum.
12. What is the role of RuBisCO in the Calvin cycle?
RuBisCO catalyzes the fixation of CO₂ into an organic molecule, initiating the Calvin cycle.
13. What is the difference between cyclic and non-cyclic photophosphorylation?
Cyclic photophosphorylation produces only ATP, while non-cyclic photophosphorylation produces both ATP and NADPH.
14. What is PSI and PSII?
PSI and PSII are two photosystems involved in the light-dependent reactions of photosynthesis.
15. Which comes first, light or dark reaction?
The light reaction occurs first, followed by the dark reaction.
16. What is the full form of ATP?
ATP stands for Adenosine Triphosphate.
17. What is the difference between C3 and C4 plants?
C3 plants fix CO₂ directly using RuBisCO, while C4 plants have a specialized mechanism to prevent photorespiration.
18. Is tomato a C3 plant?
Yes, tomato is a C3 plant.
19. What is the role of NADH in cellular respiration?
NADH is an electron carrier that helps generate ATP in cellular respiration.
20. What is the difference between the ground and excited state?
The ground state is the normal energy level of an electron, while the excited state is a higher energy level after absorbing light.
