AP BIOLOGY

Detailed explanation-1: -When the stem grows against the force of gravity (upwards), this is known as a negative gravitropism. When a root grows in the direction of the force of gravity (downwards), this is known as a positive gravitropism.

Detailed explanation-2: -Plant parts can grow with or against gravity. This type of tropism is called gravitropism. Roots of a plant grow downward and exhibit positive gravitropism. Stems, on the other hand, exhibit negative gravitropism since they grow upwards and against the force of gravity (see Figure 1).

Detailed explanation-3: -The roots of a plant demonstrate negative gravitropism, and the shoots of a plant demonstrate positive gravitropism.

Detailed explanation-4: -For instance, the roots of the plants grow towards the gravitational field whereas the stem grows away from the gravitational field. The downward growth of roots is an example of a positive gravitropism whereas the upward growth of roots is an example of negative gravitropism.