Nitrogen fixing bacteria take nitrogen gas from the air and convert it into usable nitrogen in the forms of ammonia, ammonium, nitrates and nitrites. This process is known as what?
fixation
assimilation
nitrification
denitrification

Food webs - transferring energy and matter from one level to another. here you see four food webs. one or more are incorrect. which food web(s) show the correct sequence of organisms, from start to top level consumer? a) a b) d c) c d) a and d