In scotoactive opening, stomata remain open during
(a) day
(b) night
(c) early morning only
(d) throughout the day and night

Options

A. day
B. night
C. early morning only
D. throughout the day and night

Answer

**Step-by-Step Solution:**

1. **Understanding Scotoactive Opening**: The term "scotoactive" refers to a type of stomatal behavior that is influenced by light conditions. Specifically, scotoactive stomata are known to open in the absence of light.

2. **Identifying the Time of Opening**: Scotoactive stomata are characterized by their opening at night. This is contrary to most stomata, which typically open during the day to facilitate photosynthesis.

3. **Reason for Night Opening**: The opening of stomata at night in scotoactive plants is primarily due to the metabolism of organic acids. During the night, these plants can utilize stored organic acids for respiration, leading to the opening of stomata.

4. **Behavior During Daylight**: In contrast to their behavior at night, scotoactive stomata close during the day. This adaptation helps to minimize water loss during the hotter daytime hours.

5. **Location of Stomata**: Scotoactive stomata are generally found on the lower surface of the leaves of certain plants, particularly succulent xerophytes, which are adapted to arid environments.

6. **Conclusion**: Based on the characteristics of scotoactive stomata, they remain open during the night and closed during the day. Therefore, the correct answer to the question is (b) night.

**Final Answer**: (b) night

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