mental vs biological science

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

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

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

mental (adjective)	biological science (adjective)
involving the mind or an intellectual process
of or relating to the mind
of or relating to the chin- or liplike structure in insects and certain mollusks
of or relating to the chin or median part of the lower jaw
affected by a disorder of the mind