Question

Stomatal opening and closing is made possible because of

• A. Change in turgidity of guard cells
• B. Radial arrangement of cellulose microfibrils in the guard cells
• C. Thick and mildly elastic inner wall of the guard cells
• D. All the above

Answer 1

The correct option is D All the above

Stomata are tiny pores confined to the epidermis of the leaves which grants in gas exchange. Each stoma is surrounded by a specialized cell called guard cells, which are kidney-bean shaped with thick inner walls and thin outer walls. When the cells become turgid the guard cells become swells up and the outer wall is bent outward causing the crescent shape. These are the cells helps to regulate transpiration by opening and closing of stomata. Guard cells change their shape when water and salts accumulate in them because it posses elastic cells and is lateral in the arrangement. In cell wall of guard cells, cellulose microfibrils are arranged radially, in the form of loops and this arrangement is known as radial micellation. This arrangement is important for proper stomatal function. Cellulose microfibrils prevent stretching and shrinking in the order parallel to their direction. Since the microfibrils are organized as ‘loops’ over the circumference of the guard cells, this restraint grants only raise in length when the cells are turgid.

So, the correct answer is option D.