Question

How will you identify monocots and dicots on the basis of stomata? Why is the number of stomata greater on the lower surface of a leaf?

Answer 1

Hint:Monocots and dicots can be classified based on the type of guard cell present. The transpiration rate is lower on the lower surface of a leaf.

Complete answer
First we should know about stomata to answer this question. Stomata are the small openings that are found on the plant leaves. Beneath the light microscope we can see stomata. Stomata are found on stems and other plant parts in some of the species. Stomata play a significant role in photosynthesis and gaseous exchange. They monitor by transpiration rate by closing and opening. The stomata have minute pores called stomata that are protected by a pair of guard cells. Stomata become open and close as per guard cell turgidity. The pore surrounding cell wall is flexible and tough.
Now let’s answer the given questions
In a dicot leaf, the stomata guard cells are shaped like a kidney and in a monocot leaf, they are dumb-bell shaped. Monocot leaves contain stomata on both sides, but some dicots only have stomata on one side of their leaves (generally in the lower surface). Stomata are arranged in tightly ordered rows in monocot leaves, while the dicots have some kind of crazy-paving of them.
Stomata are one of the critical parts of gaseous exchange. The surface of the leaves is made of thousands of stomata. Most are on the lower side of the leaves. Stomata, along with gaseous exchange, aids in transpiration. Therefore, if there are more stomata on the upper surface of the leaf, the transpiration rate will increase, but if the stomata are positioned on the lower surface, it will be less exposed to sunlight, so less transpiration will occur

Note: Typically the form of guard cells differs in both dicots and monocots, though the mechanism remains the same. The lower surface of the leaf has more stomata because it is present in the shade and is therefore colder, indicating that evaporation will not occur as much, thus the plant will lose less water.