Gradualism is Darwin’s proposition that the differences between even radically different organisms have evolved by small steps through intermediate forms, not by leaps

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#Unit 6. System Physiology – Plant

The NDH pathway is especially prominent during oxidative stress. 

The second pathway involves a ferredoxin‐quinone oxidoreductase that is sensitive to antimycin A.

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#Unit 6. System Physiology – Plant

Some of the cytochrome b6 f complexes are found in the stroma region of the membrane, where photosystem I is located. Under certain conditions cyclic electron flow from the reducing side of photosystem I, through the b6 f complex and back to P700, is known to occur.

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#Unit 6. System Physiology – Plant

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#Unit 6. System Physiology – Plant

When PSII receives more light than PSI, plastoquinone becomes predominantly reduced, resulting in activation of the LHCII kinase. The kinase phosphorylates LHCII, resulting in migration of LHCII away from the granal region where it can associate with PSI, thereby adjusting the relative excitation of PSII and PSI.

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#Unit 6. System Physiology – Plant

STN7 kinase mediated phosphorylation of LHCII molecules displace them to PSI

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#Unit 6. System Physiology – Plant

Damage caused by singlet oxygen and its reactive products can decrease the efficiency of photosynthesis in a process known as photoinhibition.