Please help me with this quick

Which element is used in photosynthesis found in atmosphere and fixed by bacteria?

All ova contain sex chromosomes corresponding to: x y xx xy

Deserts (especially true deserts) are not easy places for animals to live. animals who live in them often have special features that them survive. which adaptation would be for this group of animals? a) keen eye sight b) short, narrow legs c) tolerate heat d) webbed feet