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Cyclic photophosphorylation takes place in the thylakoid which lacks:
A. Electron transport system
B. Enzyme FNR (ferredoxin NADP reductase)
C. Lumen
D. Photosystem with absorption peak 700nm

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Last updated date: 12th Jul 2024
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Answer
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Hint: Within the chloroplasts of cyanobacteria, thylakoids are membrane-bound compartments. Thylakoids are where photosynthesis' light-dependent reactions take place. A thylakoid membrane surrounds a thylakoid lumen in thylakoids.

Complete answer:
Cyclic photophosphorylation is a photophosphorylation mechanism that causes electrons to pass in a cyclic pattern in order to synthesise ATP molecules. Plant cells simply convert ADP to ATP in this step to provide immediate energy to the cells.
Process of cyclic Phosphorylation:
Photophosphorylation of this kind normally takes place in the thylakoid membrane.
In cyclic electron flow, the electron starts in a pigment complex called photosystem I.
It then moves on to ferredoxin and finally cytochrome b6f after passing through the primary acceptor.
Cytochrome b6f is a cytochrome that is identical to that present in mitochondria.
After that, the electron goes to plastocyanin and then back to chlorophyll.
Throughout this electron transport chain, a proton-motive force is created, which pumps H+ ions across the membrane and creates a concentration gradient that can be used to power ATP synthase during chemiosmosis.
This whole process is referred to as cyclic photophosphorylation. It does not contain O2 or NADPH.
' Electron transport system' does not occur in Cyclic phosphorylation.

So the correct answer is Option A) Electron transport system

Note:
The electron transport mechanism takes place in the mitochondrial cristae, which contains a number of cytochromes (enzymes) and coenzymes. These cytochromes and coenzymes act as transport and transfer molecules.