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Phototropism is the growth response to light.

Tropism is a growth response in all or part of a plant due to an external stimulus. Phototropism in particular is in response to light (photo-) and may be further divided as negative or positive phototropism.

Negative phototropism (also known as skototropism) will cause the plant to move away from light, while positive phototropism – which is the most common form – will cause the plant to move towards light.

Phototropism is valuable for plants in competing with neighboring organisms in the search for sunlight that allows it to thrive and capture the most energy.

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