Biology : PU-CET (U.G) 2015 Panjab University Entrance Exam With Answers

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28.

Stomata Open At Night And Close During Day Time In :

A: Mesophytes
B: Hydrophytes
C: Shrubs
D: Succulents

The answer is: D

Explanation

Stomata open at night and close during the day time in "Succulents". Succulents are plants that have adapted to arid environments and have specialized structures that allow them to store water, such as thick stems, leaves, and roots.

In order to conserve water, succulents keep their stomata closed during the hot and dry day time, when evaporation rates are high. Instead, they open their stomata at night when temperatures are cooler and humidity is higher, allowing them to take in carbon dioxide for photosynthesis while minimizing water loss through transpiration.

In contrast, mesophytes are plants that grow in moderate temperature and moisture conditions, and their stomata are typically open during the day time.

Hydrophytes are plants that grow in aquatic environments and have adapted to exchange gases directly with the water, rather than through stomata.

Shrubs are a type of woody plant that can grow in a range of environments, and their stomata opening and closing patterns may vary depending on their specific adaptations.