Talk about the types of photosystems and their activity

There are two photosystems: photosynthesis photosystems I and II, numbered in the order of their discovery. They differ in the chlorophyll "a" molecule of the reaction center. Photosystem I “has" the P700 reaction center ("P" stands for pigment and "700" optimal absorption peak in nanometers), which means it does not absorb wavelengths longer than 700 nm and photosystem II has the center P680. The chlorophyll "a" molecules of the reaction centers are identical except that they are associated with different proteins. Both photosystems are connected by a chain of electron transport. They operate simultaneously and continuously.