Question

The presence of stomata on the surface of the dorsiventral leaf is a mechanism of
(a)Reduction in transpiration
(b)Protection from dust
(c)Proper regulation of transpiration
(d)Increase in transpiration

Answer 1

They are openings on the surface of plants, found mainly on the leaves, but also on stems and other organs. They are the pores that are surrounded by specialized parenchyma cells, called guard cells.

Complete answer:
Transpiration is the process of evaporation of water through aerial parts ( leaves and stem ) of plants. About 97-99 % of the water that is absorbed through roots is lost by transpiration. In leaves, there are pores called stomata for transpiration.
In dorsiventral leaves, these leaves are slightly different in anatomy like the number of stomata. On the lower side or ventral side more no. of stomata are present in comparison to the dorsal side to reduce transpiration. As sunlight can not directly reach the stomata present at the lower side.

Additional Information: -The stomata is surrounded by two parenchymatous guard cells.
-The guard’s cells are kidney-shaped structures consisting of Chloroplasts.
-Stoma helps in the process of respiration and photosynthesis.
-The mechanism of opening and closing of stomata is dependent upon the turgor pressure of the guard cells.
-When the sugar or solute which is formed during photosynthesis due to the presence of light, enters the guard cells then the osmotic potential and water potential of the guard cell is lowered.
-The water potential between guard cells and neighboring cells will increase the turgor pressure in the guard cells.
-The guard cells will become turgid and swell causing stomatal opening.
-When the light is absent no starch is produced as no photosynthesis occurs.
-The concentration of solute in guard cells gets lowered leading to the movement of water from the cell to the outside through osmosis.
-The guard cells become flaccid and the stomata get closed.
So, the correct answer is, ‘Reduction in transpiration.’

Note: -Stomata are small pores present in the leaf. They are surrounded by guard cells which help in closing and opening of stomata.
-The stomatal ratio is the ratio of the stomatal frequency on the adaxial surface to that on the abaxial surface.
-The guard cells become turgid and swollen due to the accumulation of potassium ions resulting in lowering of water potential and opening of stomata while the closing of stomata occurs due to the lowering amount of water, light, and carbon dioxide decreasing photosynthesis.