Why is phototropism useful to plants?

Question

Why is phototropism useful to plants?

and why is geotropism useful to plants?

Answer 1

Phototropism: plant stems grow towards light ( positive ), important for photosynthesis. They need light for photosynthesis so theres your answer.

Gravitropism/geotropism: a plant will grow so that it stays oriented relative to the source of gravity (the earth).If a plant is knocked down the shoot will grow faster on the lower side until the shoot is more-or-less standing up again ( negatively to gravity by growing up toward the sky ).

The root grows down into soil ( direction of gravity > positive ); that`s important for stability and uptaking nutrients.