Question

The lower surface of leaf will have more number of stomata in a
A)Dorsiventral leaf
B)Isobilateral leaf
C)Both (a) and (b)
D)None of these

Answer 1

Hint: Stomata are tiny openings located in young shoots of plants and epidermis of leaves. They govern the gas exchange process in plants. Stomata include a pair of specialized cells that girdle around the opening and termed as guard cells. They are responsible to check and regulate the size of the closing and opening of the stomata.

Complete answer:
The stomata are apertures in the epidermis; each bounded by two guard cells. Stomata occur in vascular plants which include lower vascular plants such as horsetails, ferns, gymnosperms, and angiosperms. Guard cells control the size of the stomatal aperture which then leads into a sub-stomatal intercellular space, known as sub-stomatal chamber.

The stomata are most common on green aerial parts of plants, particularly the leaves. They can also occur on stems, but less commonly than on leaves. The aerial parts of some chlorophyll-free plants lack stomata, but rhizomes possess them. Stomata occur on some submerged aquatic plants and not on others. The colored petals of flowers often have stomata, but sometimes non-functional. Fruits also can have stomata. Stomata are found on stamens and gynoecium. They can be distributed on the two sides of a leaf as:

1)Amphistomatous leaf has stomata on both surfaces. Most plants have such a distribution.
2)Hypostomatous leaves possess stomata only on the lower surface. The leaf of poplar is an exception as it possesses the stomata on both surfaces.
3)Epistomatous leaf has stomata only on the upper surface. Few of the floating plants are epistomatous.
4)Heterostomatous leaves possess stomata occurring more than twice the frequency on an abaxial surface than on an adaxial surface.
5)Isostomatous leaf has stomata which have equal stomata on both surfaces.

Hence, the correct answer is option (A)

Note: The stomatal ratio is the ratio of stomatal frequency on the adaxial surface to that on the abaxial surface. Stomata are distributed between dicots and monocots in different ways, between the top side and underside of leaves, between different plant species, etc. Mostly, stomata are found on surfaces of plants that flourish under greater availability of light, lesser carbon dioxide levels in the atmosphere and also in moist environments.