Question

How do plant roots "know" to grow downward? This is a plant response called

A) gravitropism.
B) hydrotropism.
C) phototropism.
D) thigmotropism.

Answer 1

A) gravitropism is how they "know"

Answer 2

The correct answer would be A) gravitropism

Gravitropism or geotropism refers to the differential growth of a plant in response to the gravitational pull.

For example, roots show positive geotropism, that is, they grow in direction of gravitational pull.

In contrast, shoots show negative geotropism, that is, they grow in opposite direction as compared to the direction of gravitational pull.