PHOTOSYNTHESIS
LIGHT DEPENDENT REACTIONS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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PSI is named P700
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PSI is named P680
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PSII is named P700
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PSII is named P680
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Detailed explanation-1: -This reaction centre is also known as photocentre. These centers can release electron upon absorption of energy. In PS I, the reaction centre chlorophyll a has an absorption peak at 700 nm, hence is called P700, while in PS II, reaction centre has an absorption peak at 680 nm and is called P680.
Detailed explanation-2: -PS I absorbs the light of wavelength 700nm whereas PS II absorbs light of wavelength 680nm, so they are referred as P700 and P680 respectively.
Detailed explanation-3: -Photosystem I (PSI) has a P700 reaction centre containing chlorophyll that takes the electron and associated hydrogen donated from PSII to reduce NADP+ to NADPH.
Detailed explanation-4: -Both photosystems contain many pigments that help collect light energy, as well as a special pair of chlorophyll molecules found at the core (reaction center) of the photosystem. The special pair of photosystem I is called P700, while the special pair of photosystem II is called P680.
Detailed explanation-5: -P680 is also called RC (Chl) of PSII, and is composed of a Chl a dimer PD1 and PD2 which, upon light excitation, forms an excited state P680* and subsequently releases an electron to an acceptor, generating the cation radical P680•+.