mental vs biology

mental is not a noun while biology is a noun.

Word	Noun	Adjective	Verb	Adverb
mental	No	Yes	No	No
biology	Yes	No	No	No

mental (noun)	biology (noun)
	the science that studies living organisms
	all the plant and animal life of a particular region
	characteristic life processes and phenomena of living organisms

mental (adjective)	biology (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