Question

Stomatal index ‘I’ is equal to
(Where S= number of stomata per unit area and E= number of epidermal cells in the same unit area)
A. S/E-S
B. S/E+S
C. E/S+S
D. E+S/E

Answer 1

A stoma also known as stomata, it is a pore present in the epidermis of leaves, stems, and other organs, function of these stomata controls the rate of gas exchange. The pore has the outer layer of specialized parenchyma also understood as guard cells which help in control the size of the stomata opening.

Complete Answer:
- Stomatal frequency is defined as the number of stomata per unit area of leaf.
- Stomatal frequency changes according to size of cell like if guard cells are smaller in size they are having a high amount of stomatal frequency.
- Stomatal index relates the number of stomata per unit leaf area to the number of epidermal cells in same leaf area
- Stomatal index (I) is the average number of stomata cells present per square millimeter of the epidermis of the leaf.
- Or we can say that, it is the percentage of the number of stomata cells present to the total number of epidermal cells.

So, correct answer I = S / E + S, where I = stomatal index, S = number of stomata cells per unit area, and E = number of epidermal cells per unit area.

Note: Function of stomata cells: gaseous exchange, water balance, and help in photorespiration, opening and closing of stomata. There are various types of stomata: Actinocytic, Anisocytic, anomocytic, diacytic, hemiparasitic, paracytic, gramineous, hexacyclic, tetracytic, hypocytic,pericytic,desmocytic, and polycystic.