Question

Which do not have stomata?
A. Submerged hydrophytes
B. Hygrophytes
C. Mesophytes
D. Xerophytes

Answer 1

Hint: Stoma refers to the pores present in the epidermis layer of plant parts like leaves, stems, etc. The stomata include the stoma plus the guard cells that surround these pores. The stomata are present to perform gaseous exchange through the outermost layer of plants. They are present in plants that are exposed to the atmosphere.

Complete answer: All of the terrestrial plants consist of stomata. It is a key component in the functioning of plants. The carbon dioxide required for the process of photosynthesis is taken in with the help of stomata. The stomata consist of pores present on the epidermal layer of the leaves, or some stems. The pores are surrounded by guard cells that assist in the opening and closing of the stomatal pores. These are made of parenchyma cells. The stomata pores stay clogged with water vapour. At the time of photosynthesis that is during the daytime, the stomata pores are opened up by guard cells. When the pores open the plant loses its water through evaporation. This process is called transpiration. During transpiration, the pores get empty and carbon dioxide from the atmosphere enters the plant. This aids in the process of photosynthesis. Also, oxygen is thrown out of the plant through gaseous diffusion occurring in stomata. Oxygen is a by-product of photosynthesis and thus needs to be expelled. Submerged hydrophytes are plants that stay fully submerged under the water. They do not contain stomata as no transpiration is required in these plants. The gaseous exchange takes place through the process of diffusion.
i. Hygrophytes grow in wet and humid conditions but have stomata for gaseous exchange. The mesophytes grow in moderate conditions and have stomata.
ii. The xerophytes are plants that grow in water-scarce conditions. They also have stomata that are shrunken in nature.
Hence, the right answer is option A.

Note: Submerged hydrophytes epidermal layer consists of the chloroplast that helps in absorption and assimilation. Also, the submerged hydrophytes have no cuticle covering. Some examples of submerged hydrophytes are Utricularia, Hydrilla, etc.