Question

an iris plant blooms when days are longer. this is an example of which type of plant response? gravitropism photoperiodism thigmotropism hydrotropism

Explanation:

• Gravitropism is the plant's response to gravity.
• Photoperiodism is the plant's response to the length of day and night.
• Thigmotropism is the plant's response to touch.
• Hydrotropism is the plant's response to water.

Since the iris plant blooms when days are longer (related to day - night length), it is a response to photoperiod.

Answer:

photoperiodism