How many letters does the top answer for “an orienting response to gravity” have?

The most common answer is geotropism (10 letters).

Crossword clue: an orienting response to gravity

1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

geotropism 10 letters wn-def

an orienting response to gravity

an orienting response to light 50% similar → phototropism

an orienting response to the sun 50% similar → heliotropism

an orienting response to warmth 50% similar → thermotropism