Photosynthesis is the process where light that comes from the sun is converted into chemical energy in plants. During photosynthesis, light energy provided by the sun, water, and carbon dioxide are converted into the products sugar, water, and oxygen. Oxygen is released as a byproduct of a water molecule splitting to provide an electron. Oxygen is specifically produced during the light reaction portion of photosynthesis, which is the stage that is dependent on light. The light is absorbed by chlorophyll and used to convert to chemical energy. This chemical energy is represented by ATP and NADPH. Water molecules are separated into hydrogen and oxygen molecules. The hydrogen molecules are used to produce more NADPH. The oxygen molecules are released. In this experiment, we focused on the emission of oxygen.
Throughout the experiment, we analyzed and collected data based on types of light used in the photosynthesis process. The variables our group tested were white light and blue light. We chose these variables because we wanted to know whether or not photosynthesis would be affected if a different wavelength of light was used. Studying this variable is important because previous research and other studies have shown that the color and strength/intesity of light on plants affect plant systems. Plants need to survive and produce energy. Sunlight usually fluctuates from different intensities and wavelengths throughout the day, which would have an effect on the photosynthetic rate. Light not only begins the process of photosynthesis, but it also affects environmental cues like plant flowering, gene expression, and leaf movement (Ohara, Fukada, & Tokuda, 2015). Studying different light wavelengths and intensities on plants can provide resourceful information to researchers, who can then design artificial lighting conditions in closed environments, such as plant factories or greenhouses. Therefore, experimenting with different wavelengths of light and their effects on plant photosynthetic rate is significant.
Our group hypothesized that under a different wavelength of light, a plant would respond according to that wavelength and produce different results, compared to if the plant was exposed to regular white light………..
In order to test our hypothesis, we used an apparatus that would hold the leaf that we would be testing, while providing the light. Connected to the apparatus was a bag of carbon dioxide, which we would use to fill the chamber containing the leaf. An oxygen sensor was also connected to the apparatus. The sensor was connected to a computer which recorded the oxygen production and the photosynthetic rate on the program, PhotoLab. The variables that were tested were white light, the control variable, and blue light, the experimental variable. The dependent variables were the percentages of oxygen produced and the photosynthetic rates. To start the experiment, all of the carbon dioxide in the bag was slowly added to the leaf chamber. The program would represent this by showing a decrease in % in Graph 1. A beaker of water was placed above the chamber. When the % had leveled off on the graph, the light was switched on. This began the photosynthesis process. The beaker of water was replaced every 15 minutes to avoid overheating. Data was collected for about 30 minutes until the % concentration maintained a steady rate. For the experimental variable, blue light, another leaf was placed in the chamber and the same procedure was repeated. To mimic blue light, a small square of blue filter paper was placed between the chamber and the beaker of water, so that the light coming into the chamber would be blue. To accurately compare the rate of photosynthesis on the two different leaves, the surface area of each leaf used in the experiment was calculated. The leaf was placed under an acetate grid to calculate the surface area. After the data was collected, the photosynthetic rate of each leaf would be divided by its respective surface area in order to accurately compare the two rates.