persistent vs biological science

persistent is not a noun while biological science is a noun.

Word	Noun	Adjective	Verb	Adverb
persistent	No	Yes	No	No
biological science	Yes	No	No	No

persistent (noun)	biological science (noun)
	the science that studies living organisms

persistent (adjective)	biological science (adjective)
retained; not shed
never-ceasing
stubbornly unyielding
continually recurring to the mind