Practice MCQ Questions and answers on Biology-GK

The exchange of oxygen and carbon dioxide in the leaf (as well as the loss of water vapour in transpiration) occurs through pores called stomata (singular = stoma). Normally stomata open when the light strikes the leaf in the morning and close during the night.

The numerous minute pores in the epidermis of a leaf are called stomata.

Stomata helps in exchange of gases.

Guttation is the loss of water in the form of water droplets from hydathodes (small pores) on the leaf margin of a small herbacious plant.

In CAM plants, stomata are open during the night and closed during day time. This is an adaptation of cutting transpiration loss of water. CAM plants grow in deserts and are exposed to high temperatures.Their stomata are open during the night for carbon dioxide uptake but closed during the day to prevent water loss.
Thus, the correct answer is option C.

The uptake of water can be measured using a potometer. Under normal circumstances, the rate of water uptake gives a measure of the rate of transpiration . A simple potometer is a piece of capillary tubing to which a plant has been connected. Ganong's potometer is the right answer.