AP BIOLOGY

Detailed explanation-1: -Phototropism. Plants grow towards or away from the light, the type of tropism in the response to light is called phototropism. In general, the stems usually show positive phototropism, while roots show negative phototropism.

Detailed explanation-2: -Plant Tropisms A tropism is a turning toward or away from a stimulus in the environment. Growing toward gravity is called geotropism. Plants also exhibit phototropism, or growing toward a light source. This response is controlled by a plant growth hormone called auxin.

Detailed explanation-3: -The response of an organism, usually a plant, to an environmental stimulus is called a tropism. Some common plant stimuli include light, gravity, water, movement of the sun, and touch. The naming of the tropism is associated with the stimulus.

Detailed explanation-4: -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. A tropic movement is defined as either positive or negative tropism; not as downward and upward tropism.