The influence of the relative duration of day and night on the flowering response of plants is called

Options

A. Phototropism
B. Photoperiodism
C. Vernalisation
D. Geotropism

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the influence of the relative duration of day and night on the flowering response of plants. This indicates that the timing of light and darkness plays a critical role in how plants flower.

2. **Identifying Key Terms**: The key terms here are "relative duration of day and night" and "flowering response." This suggests that we are looking for a term that describes how plants respond to the length of day and night.

3. **Types of Plants Based on Light Exposure**:
- **Long Day Plants**: These plants require more than 12 hours of light and less than 12 hours of darkness to flower. They thrive in longer daylight conditions.
- **Short Day Plants**: These plants need less than 12 hours of light and more than 12 hours of darkness to initiate flowering. They thrive in shorter daylight conditions.

4. **Understanding the Concept**: The phenomenon where plants respond to the length of day and night is crucial for their flowering. This response is regulated by the amount of light they receive, which influences their biological processes.

5. **Identifying the Correct Term**: The term that describes the influence of day and night duration on flowering is known as **photoperiodism**. This is the biological response of organisms to the length of day or night.

6. **Eliminating Incorrect Options**:
- **Phototropism**: This refers to the growth of plants in response to light direction, not the duration of light.
- **Vernalization**: This is a process related to the exposure of seeds to cold temperatures to promote flowering, not related to day length.
- **Geotropism**: This refers to plant growth in response to gravity, not light duration.

7. **Conclusion**: Based on the definitions and explanations, the correct answer to the question is **photoperiodism**.

**Final Answer**: The influence of the relative duration of day and night on the flowering response of plants is called **photoperiodism**.

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