Question

Which of the following keeps its stomata open during the night and closed during the day?
a) Cactus
b) Water lily
c)Ivy
d)Hibiscus

Answer 1

Hint: Stomata is the pore opening present on the surface of the leaves. It helps in transpiration and photosynthesis of the plant. The opening and closing of the stomatal pore are regulated by its guard cells. The presence of the stomata on the leaves of the plant also helps it to cool down.

Complete answer:
The cactus is a desert plant and it survives in extreme conditions. The stomata present of it closes during the day time and opens only in the night time. The amount of sunlight they receive is in excess quantity and the rate of transpiration tends to increase. If an increased rate of transpiration would occur then the plant will dry out soon. So, to prevent this they have developed a mechanism in which they open during the night and take in carbon dioxide present in the air and the gaseous exchange is done before the daytime. In the daytime, they close their stomata so that less amount of transpiration can take place. Such adaptation has made it possible for them to survive in the extreme conditions of the deserts. The stomata present on the modified stem of the plant are deeply sunken and are in abundance on the lower surface as compared to the upper surface of the plant.
So, the answer is ‘cactus’.

Note: The stomata help in the regulation of the gases between the atmosphere and the plants. In normal plants they open during the daytime so that photosynthesis can occur easily and they close during the night time to reduce the rate of transpiration of the plant.