What are the reactants for the photosynthesis reactions?

Which taxon group is more specific, in regards to organisms that are in that group? mammalia animalia

The circles, or orbits, for electrons are called energy levels. each level can hold only a certain number of electrons. add electrons to each level until you can't add any more. how many electrons can each level hold?

Aperson with age is more likely to catch diseases that healthy people usually don’t catch.what are these infections called?