AP Biology Practice Questions

Answer: A, The turning of the Alpine buttercup flower to the East at sunrise is an example of tropism. This particular example can be further classified as heliotropism.

Key Takeaway: Tropism defines any turning movement of a plant in response to environmental stimuli. Tropism can be induced by gravity, chemical stimuli, sunlight, temperature, touch, or pathogens. Tropisms mostly refer to plants and other types of organisms incapable of direct physical movement. In organisms capable of motility, movement in response to stimuli is called either taxis or kinesis.