Eli5: How do plants move toward the light? How do they sense it and also move toward it in response?

Question

Eli5: How do plants move toward the light? How do they sense it and also move toward it in response?

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Answer 1

Plants growing toward light is called phototropism.

Plants have molecules that act when they detect light to encourage hormone changes in the plant.

These hormones, called Auxin, encourage the plant cells to change and grow toward the light source.

Answer 2

As I recall the plant cells are photoreactive – literally when light hits them they have a reaction. Presumably through the chemical the other commented posted.

Part of that reaction is that the cells constrict a bit.

This means the the side of a stem that has light on it will get shorter, and this bends the entire stem over towards the light source.

There is I’m sure more to it in terms of stimulating growth in areas of the plant that have light hitting them, but this is how the plants ‘move’