Question

Product of Cyclic Pathway

• A. NADPH
• B. ATP
• C. H$^+$
• D. H$_2$O

Hint:

In photosynthesis, cyclic photophosphorylation is primarily used to produce ATP, which is essential for the Calvin cycle. Non-cyclic photophosphorylation produces both ATP and NADPH.

Answer 1

The Correct Option is B

Solution: The question pertains to the product of the cyclic photophosphorylation pathway in photosynthesis. In photosynthesis, light energy is converted into chemical energy, specifically in the form of ATP and NADPH, through two main pathways: cyclic and non-cyclic photophosphorylation.

Cyclic Photophosphorylation: In cyclic photophosphorylation, electrons are excited by sunlight and transferred through a series of protein complexes and electron carriers. Key components involved include:

• Photosystem I (PSI), which absorbs light and boosts electrons to a higher energy level.
• Electron transport chain, where electrons are cycled back to PSI.

During this process:

• No water is split, so no oxygen (O₂) is released.
• NADPH is not produced since electrons do not reach NADP⁺ reductase.
• ATP is generated through the chemiosmotic mechanism as protons are pumped across the thylakoid membrane creating a proton gradient. When protons flow back into the stroma through ATP synthase, ATP is synthesized.

Conclusion: The primary product of the cyclic pathway is ATP.

Pathway	Products
Cyclic Photophosphorylation	ATP