facultative vs biological science

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

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

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

facultative (adjective)	biological science (adjective)
able to exist under more than one set of conditions
of or relating to the mental faculties
granting a privilege or permission or power to do or not do something
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