Mrs. Pensinger's Biology Blog: Leaf Stomata

Hello again! Today I am going to write about a lab we did awhile ago that I never got around to posting about, but I think deserves a post! In my honors biology classes we spent some time using the microscopes to see if we could see the stomata in plant leaves and then calculate the stomata density for the leaves. Stomata are small pores in the top layer of leaf cells that, when open, allow materials such as carbon dioxide and water to move into our out of a leaf. We talked about the relationship of these stomata to the process of photosynthesis- they must be open to allow needed carbon dioxide into plant leaves for photosynthesis. However, when open, water is able to move out of the leaf, which could be harmful for plants that live in areas where water is scarce. Students discussed how a plant's climate could influence it's stomata density- plants in hot, dry areas might benefit from fewer stomata so that they can conserve water.

Each student group was given a leaf from a plant and was tasked with making a microscope slide of the epidermal layer of the leaf so that stomata could be viewed. Before beginning, students measured and calculated the surface area of the leaf so that they could determine stomata density after viewing their slide. To make the slide, students painted a thin strip of clear fingernail polish on a section of the underside of the leaf. Once the polish was completely dry, they placed a piece of clear tape over the polish and pressed the tape down into the polish. They then carefully peeled the tape from the leaf and placed it on a microscope slide. They examined the slide under the microscope to hopefully view the stomata! Students counted the stomata in the field of view of the microscope, then moved the slide to two other areas and did the same. They took the average number of stomata from the three areas and divided this by their surface area to calculate the stomata density of the leaf! Pretty cool!