Biology Practicals: Distribution of stomata on the two surfaces of a leaf

objective

To study the distribution of stomata on the lower epidermis of a leaf.

requirements

fresh leaf, forceps, needle, brush, watch glass, petridish , glass slides, coverslips, safranine, water

1st step

take out the epidermal peels from the lower surface of the given leaf and put it in a watch glass. The peel can be taken out by tearing the leaf obliquely with a single jerk or scraping it with a blade.

step 2

stain the peels with safranin by adding a few drops of the stain in the watch glass

step 3

cut a small rectangle or square piece from each peel and mount them in water on the slide

step 4

cover the peel with coverslips and observe it under the microscope

Observation

In the given leaf there are a large number of stomata in the lower epidermis

precautions

1. curling of the peel should be avoided 2.always use brush to transfer the peel from the watch glass to the slide

what are stomata?

minute pores present on the surface of leaves and young shoots

what is the function of stomata?

stomata are meant for the exchange of gases. Plants also lose water in vapour form through stomata

what are guard cells?

guard cells are specialized cells, which surround the stomatal pore and are responsible for the opening and closing of the stomata

from which surface of a dicot leaf, will you take out the peel to observe the stomata?

dicot leaf is a dorsiventral leaf, which has stomata on the lower surface. Peel can be taken out from the lower surface to observe stomata

from which surface of a monocot leaf, will you take out the peel to observe the stomata?

Monocot leaf is an isobilateral leaf, having stomata on both the surfaces. Peel can be taken out from either surface of the leaf to observe the stomata

what is transpiration

loss of water in vapour form from the aerial parts of the plant is called transpiration

why are the stomata absent in submerged aquatic plants?

because, in submerged, aquatic plants exchange of gases takes place through the general surface by diffusion

what is the significance of transpiration

transpiration helps in absorption of water and ascent of sap. It also prevent heat injury by its cooling effect