Plants have many parts. One of these parts is called the leaf, which is the organ responsible for making food and can range from only a few millimeters to more than 60 feet long. Leaves turn sunlight and carbon dioxide into food in a process called photosynthesis, serve as storage organs, and many help to provide specialized structures. One of these structures is called stomate, or leaf pore, and is critical to survival of the plant.
Stomata are holes in the leaf cuticle, the waxy layer on the outside of leaves helping to waterproof them, that are surrounded by pairs of cells called guard cells. This hole in the leaf allows the leaf to exchange gases such as carbon dioxide needed for photosynthesis and oxygen, a waste product of respiration, as well as water in a process called transpiration. What is transpiration and how does it relate to these stomata?
The leaves from the plants exposed to sunlight and incandescent light are to be collected and kept separate. Each leaf will then be covered with a thick coat of clear fingernail polish over an are large enough to be examined under a microscope. After it dries, a piece of clear tape large enough to cover the area is cut and applied to the leaf. The tape is then slowly peeled off lifting the clear fingernail polish layer with it giving an impression of the leaf. This layer is then stuck to the slide and examined under 40x magnification. The number of stomata per field of view will be counted and labeled as "number of stomata per 400x field of view." This procedure is to be repeated for each of the leaves to give a total of 3 numbers of each of the light conditions (sunlight and lamp or incandescent light). The numbers of stomata are then to be averaged and these averages to be compared together to find if the source of light affects the number of stomata found in each leaf after approximately two weeks of exposure.
Transpiration is the loss of water from the plants as it evaporates out of the stomata along the leaf. As we discovered, the amount of light a leaf receives can determine how many stomata will have a greater number of stomata while those in the shade have fewer. The stomata of the leaf are open during the day and closed at night since photosynthesis can only happen during the day and are controlled by the swelling of the guard cells. There are more stomata on the bottom of a leaf because that lessens the amount of water loss through these pores. Because they are open during the day, the plant can lose up to 95% of its water through these pores. Since transpiration is such an important process in plants, it becomes important to study them. One particular method of study that we chose is changing the type of light that hits the leaf. By using the plants that we have been studying for the whole camp, we can study the affects of sunlight versus incandescent light, on the number of stomata present on a plant and see whether this is an important variable affecting the growth of the plant.
The purpose of this experiment is to study the effects of sunlight versus incandescent light in the number of stomata present on a plant and see whether this is an important variable affecting the growth of the plant.
We hypothesize that the leaf exposed to the incandescent light will have a greater number of stomata than those exposed to sunlight because the amount of incandescent light striking the leaf is much greater.
There are a large amount of growth conditions that can affect a plant. One of the most important of these conditions concerns the type of availability of light present for photosynthesis. By controlling the type of light that a plant receives, its growth can be affected. We chose to measure this growth by observing the number of stomata present on the underside of leaves exposed to incandescent light and sunlight for 10 days under a microscope. Based on the idea that there are more stomata present on leaves exposed to the sun, we hypothesis that there will be more stomata on the plants exposed to the incandescent light since they receive more light than those exposed only to sunlight.
According to our experiment, the data supports the hypothesis, which says that plants exposed to more light will have a greater number of stomata per leaf. The plants exposed to sunlight had 6, 7, and 11 stomata per 400x field view under the microscope. The plants exposed to incandescent light had 10, 16, and 19 stomata per 400x field view under the microscope as well. The leaves exposed to the incandescent light had more stomata than the leaves exposed to sunlight because the incandescent light source was much closer to the plant. As a result, it got much more light so it had more stomata.
Because of this data, we can conclude that the type of light shown on plants can affect their growth by examining the stomata present in the leaves. This shows that the leaves exposed to the incandescent light perform more respiration and photosynthesis than the leaves of the plants exposed to sunlight.