phototropism vs tropism

phototropism and tropism both are nouns.

Word	Noun	Adjective	Verb	Adverb
phototropism	Yes	No	No	No
tropism	Yes	No	No	No

As nouns, tropism is a hypernym of phototropism; that is, tropism is a word with a broader meaning than phototropism:

phototropism: an orienting response to light
tropism: an involuntary orienting response; positive or negative reaction to a stimulus source

phototropism (noun)	tropism (noun)
an orienting response to light	an involuntary orienting response; positive or negative reaction to a stimulus source