I need an answer for number three. Somebody please help I have to get this done today

Which are forms of nitrogen that are usable by humans

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

Asap brainliest will be which sentence about protists is accurate? all protists are unicellular and microscopic in nature. they have organelles, so protists are eukaryotic in nature. all protists make their own energy through photosynthesis.