Why do legume plants enrich soil? a) they remove selenium a deadly poision b) they encourage breeding of earthworms c) their roots contain nitrogen-fixing bacteria d) their root system penetrate 2 meter below the surface

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides