Question

Dorsiventral leaf is identified by the presence of
A. Stomata on both the epidermis
B. Stomata mainly present on the lower epidermis
C. No stomata on the epidermis
D. Sunken stomata on the upper epidermis

Answer 1

Hint: Stomata are minute pores present on the leaf's epidermis. They regulate the process of respiration (gaseous exchange), transpiration, and photosynthesis. The regulation of opening and closing of stomata is regulated by guard cells.

Complete answer:
Bifacial or Dorsiventral leaves are generally horizontal in orientation with a clear upper and lower surface. The upper surface of the leaf is also known as the inner, ventral, or adaxial surface and xylem found in this region whereas the lower surface is known as the outer, dorsal, or abaxial surface where phloem is present. Both of the layers surrounded by cuticles are composed of compactly arranged barrel-shaped cells.
Dorsiventral leaves are also known as dicot leaves as they are found in dicotyledons and contain well-defined dorsal and ventral sides. It is considered from each other as they differ from each other in structure as well as in appearance. It is also differentiated into palisade parenchyma as well as spongy parenchyma. Palisade parenchyma lies only on the upper epidermis that is why such leaves are called bifacial. Whereas monocotyledons contain isobilateral leaves which are also known as monocot leaves. These isobilateral leaves contain both surfaces having the same appearance and an equal number of stomata are present on both surfaces.
Stomata are present on all the surfaces containing a small number of stomata. But the lower surface of the leaf contains more stomata because they are more often in the darker shade and that is why they are cooler than the upper part which means evaporation does not occur in excess which is beneficial for all the terrestrial plants. This condition is known as Hypostomatic i.e. leaf having stomata only on the lower-side. If the number of stomata is present on the upper surface of the leaf it will lead to loss of more water during day-time and in high-temperature.

Hence, the correct answer is option (b).

Note: Leaves also serve as a reservoir of food as they form from photosynthesis, store water, and also play a defensive function. Hypostomatous leaves of dicotyledons allow it to conserve the water.