Question

Plants with scotoactive stomata perform
a. ${C_4}$photosynthesis
b. CAM photosynthesis
c. ${C_3}$photosynthesis
d. Anoxygenic photosynthesis

Answer 1

Hint: There are two types of stomata on the surface of the leaves and young stem in the plant. These stomata are photoactive stomata and scotoactive stomata. Photoactive stomata are associated with light and scotoactive stomata are associated with dark.

Complete answer:
Scotoactive stomata are the stomata that open in the dark and remain open during the night in absence of the sunlight. These stomata are found in plants like Bryophyllum. These stomata perform their activity during the night and close during the day in presence of the sunlight.

Crassulacean acid metabolism or CAM photosynthesis is a carbon fixation pathway that is carried out in arid conditions. The stomata in plants during CAM remain close during the day to reduce evapo-transpiration but open at night to acquire carbon dioxide and diffuse into the mesophyll cells.

The carbon oxide stored as the four-carbon acid malic acid in the vacuoles at night. In the daytime, the maltase is transported to chloroplast where it is covered back to carbon dioxide which is used during photosynthesis. CAM is adaptable for increased efficiency in the use of water in the plants which are grown in the arid conditions. The pre-collected carbon dioxide is concentrated around the RuBisCO, which helps in increasing photosynthetic efficiency. The pineapple is an example of a CAM plant.

Hence, the correct answer is option (B).

Note: This mechanism of acid metabolism in plants was first discovered in the plants of family Crassulaceae. The most important benefit of CAM is that it helps in keeping most of the stomata closed during the day.