Question

Select the correct option:

Identify A, B, C, D and E in the given flow chart showing Z-scheme of light reaction.

• A. A-$P_{700}$; B-$H^{+}$ acceptor; C- $e^{-}$ acceptor; D-$P_{680}$; E-$NAD{P}^{+}$
• B. A-Photo -system I ; B-$e^{-}$ acceptor; C- $e^{-}$transport system; D-Photo system II; E- NADPH
• C. A-Photo-system II; B-$H^{+}$acceptor ; C-$e^{-}$ acceptor; D-$P_{700}$; E- NADPH.
• D. A-Photo-system II; B- $e^{-}$ acceptor; C-$e^{-}$ transport system; D- photo-system I; E- NADPH.

Answer 1

The correct option is D A-Photo-system II; B- $e^{-}$ acceptor; C-$e^{-}$ transport system; D- photo-system I; E- NADPH.

A. In the non-electron transport pathway, the light energy of specific wavelengths is absorbed by chlorophylls and accessory pigments of PS II. These pigments transfer their absorbed energy to PS II reaction centre- P${}_{680}$.

B. The reaction centre- P${}_{680}$ becomes photoexcited and exudes an electron with a gain of energy. The electron is immediately accepted by the primary acceptor quinone.

C. Cyclic electron transport system occurs only occasionally when the synthesis of carbohydrate is curtailed due to the limited supply of CO${}_2$ and NADPH. This system serves the purpose of ATP when needed by the chloroplast.

D. The pigment molecules of PS I complex absorb solar radiation and transfer their absorbed electronic excitation to PS I reaction centre- P${}_{700}$.

E. The electron from P${}_{700}$ transfer to ferredoxin and reduced it. The NADP${}^{+}$ takes electrons from ferredoxin, protons from the medium and get reduced to NADPH.

So, the correct answer is 'A-Photosystem II, B-e${}^{-}$ acceptor, C-e${}^{-}$ transport system; D- photosystem I; E- NADPH'.