Which term describes a plant's response to changes in day length?

• A. Gravitropism
• B. Thigmotropism
• C. Phototropism
• D. Photoperiodism

Answer: (D)

Verified step by step guidance

1. Understand the question: The problem is asking for the term that describes a plant's response to changes in day length. This involves understanding how plants detect and respond to environmental cues like light duration.
2. Review the definitions of the terms provided: Gravitropism refers to a plant's growth response to gravity, Thigmotropism refers to a plant's response to touch or physical contact, and Phototropism refers to a plant's growth response to light direction. Photoperiodism, on the other hand, specifically refers to a plant's response to the length of day and night.
3. Identify the key concept: The question focuses on changes in day length, which is directly related to the concept of photoperiodism. Photoperiodism is the physiological reaction of organisms to the length of day or night, often influencing flowering and other developmental processes in plants.
4. Eliminate incorrect options: Gravitropism, Thigmotropism, and Phototropism are not related to changes in day length. These terms describe responses to gravity, touch, and light direction, respectively, which are different from the concept of photoperiodism.
5. Conclude the correct term: Based on the definitions and the context of the question, the term that describes a plant's response to changes in day length is Photoperiodism.