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

Leaves are the main photosynthetic organs of plants. It is covered by the epidermis on both of its surfaces. The photosynthetic tissue which contains chloroplast lies between the upper and lower epidermis and is well supplied by the vascular system. Anatomically, leaves are of two types: Dorsiventral and Isobilateral.

Complete solution:
Dorsiventral leaves are found in dicotyledonous plants. These leaves remain horizontal and the sunlight falls on their upper surface. The upper surface or the ventral surface of this leaf is called the adaxial surface and the lower or the dorsal surface is called the abaxial surface. The lower surface is lighter than the upper surface.
The epidermis includes both upper and lower surfaces. The epidermis covering the adaxial surface is called the adaxial epidermis while the epidermis covering the abaxial surface is called the abaxial epidermis.
Adaxial epidermis:
This layer is the outermost layer of the leaf which is uni-layered and is made up of parenchymatous cells. Their outer walls are cuticularized. There are chloroplasts in them. Stomata are lesser in number as compared to the abaxial epidermis. Stomata may even be absent in the adaxial epidermis.
Abaxial epidermis:
This layer is also uni-layered, made up of parenchymatous cells, and covered with cuticles. This layer contains more stomata than the adaxial surface. Chloroplasts are absent in the epidermal cells but are present in the guard cells surrounding the stoma.

Additional information:
Isobilateral leaves are found in monocotyledonous plants. These leaves remain vertical. The upper and lower surfaces of these leaves are equally green and similar to one another.
The adaxial and abaxial epidermis both contain an equal number of stomata.

So, the correct answer is Stomata mainly present on the lower epidermis.

Note:
-In dorsiventral leaves, the stomata may not be necessarily present in the upper epidermis. In some cases, it may be absent in the upper epidermis.
-Isobilateral leaves have stomata present on both surfaces.