AP BIOLOGY

Detailed explanation-1: -Growth movement of plants towards the stimulus is known as positive tropism while movement of plant/plant parts away from the stimulus is known as negative tropism.

Detailed explanation-2: -There are two forms: Positive = the plant, or a part of it, grows in the direction from which the stimulus originates. and Negative = growth away from the stimulus. A tropism is a growth movement whose direction is determined by the direction from which the stimulus strikes the plant.

Detailed explanation-3: -One important light response in plants is phototropism, which involves growth toward-or away from-a light source. Positive phototropism is growth towards a light source; negative phototropism is growth away from light.

Detailed explanation-4: -Growth in the direction of a stimulus is known as positive tropism, while growth away from a stimulus is known as a negative tropism. Common tropic responses in plants include phototropism, gravitropism, thigmotropism, hydrotropism, thermotropism, and chemotropism.

Detailed explanation-5: -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).