The Impact of Light Wavelength on Photosynthesis - Lab Report Example

The Impact of Light Wavelength to Photosynthesis This study aims to examine the effect of wavelength of light received to photosynthesis. In our experiment seven plants were placed in the CID machine and tested for CO2 level decrease. Each plant was tested for 5 minutes. Initial measurement taken 2 minutes into test and final reading was taken at 7 minutes. With the assumption that the rate of photosynthesis as manifested by CO2 consumption would be inversely related to the received light wavelength, drops in CO2 recorded and data calculated. Green wavelength having the lowest rate of photosynthesis was the only data adhering to what we had predicted. Nonetheless, our data did not support the hypothesis since the red light did not have significantly higher rate of photosynthesis among the three colors. Introduction Light is very significant to plants as it is the energy source that aids a chain of chemical reactions involve in the process of their food production called photosynthesis. With their light trapping photosynthetic pigments, plants collect light energy that then supports the production of sugar. The most important among several different pigments is chlorophyll which is responsible for green color of most plants (Light wavelength and photosynthesis) Plants absorb light energy from the sun and utilize this energy to produce sugar in the process we know as photosynthesis (Farabee, 2008). Sunlight as the primary source of light is converted to a usable chemical energy with the actions of green pigment chlorophyll. This process leads to the chemical reaction wherein water and carbon dioxide enter the cell of the leaf producing oxygen and sugar. With that leaves serves as solar collector full of photosynthetic cells (Whitmarsh). Light is a matter and an electromagnetic radiation which is a form of energy. The light that allows us to see is actually a combination of different wavelength and termed visible light. To separate these wavelengths the light must pass a prism making them all visible (Light wavelength and photosynthesis). Wavelength is defined as the distance from peak to peak and is inversely proportional to the energy. The longer the wavelengths, the more red the color; thus wavelength determines the order of colors. This creates an electromagnetic spectrum of light between red as the longest wavelength while violet as the shortest (Farabee, 2008)The light energy that is transmitted and reflected is represented with the colors that we see while those that we cannot are those that are absorbed (Light wavelength and photosynthesis) Light is absorbed through substance called pigments. For most plants chlorophyll is the green pigment responsible for absorbing all wavelengths of visible light except green. As the pigment absorbs light energy, it triggers photosynthesis; thus making the effectiveness of different wavelengths of light generating electrons relative to the action spectrum of such chemical reaction. Methods The impact of light wavelengths on photosynthesis was determined by exposing the plant Dracaena to light of different wavelengths then measuring the decrease in carbon dioxide level. With a 60 Watts soft white light bulb with red, green and yellow light filters, wavelengths of 630 to 750nm representing red, 570 to 590 representing yellow, and 490 to 560nm representing green were utilized. Two treatments were done for each of the three wavelengths, each treatment with seven replicates. Each of the seven plants was placed in the CID machine and tested for CO2 level respiration. Each plant was initially tested for drop in CO2 after two minutes of light exposure and then final measurements were obtained within seven minutes. Thus had provides us the amount of change in the level of carbon dioxide utilization within five minutes interval. Results The data in Figure 1 shows that the change in level of carbon dioxide utilization differs among colors of different wavelengths. The control where in the sunlight serves as the source of light displays a mean of 160.71 ppm CO2/min/g change in CO2 level, next to it was the yellow light with 25.6 ppm CO2/min/g, followed by red with 23.3 ppm CO2/min/g and green light with the least of 20.3 ppm CO2/min/g. Figure 1. Change in CO2 level decrease within 5 minutes interval Discussion The results we acquire through our trial are not consistent with our hypothesis that the rate of photosynthesis as manifested by CO2 consumption would be inversely related to the received light wavelength. Our data fails to display that the red light would have the highest level of carbon dioxide decrease since it has the longest wavelength of about 630 to 750nm compared to the yellow with 570 to 590nm and green with 490 to 560nm. Light, energy from the sun that reaches the earth as electromagnetic radiation, is considered both a wave nature or energy and a particle nature or matter. At its particle nature, photon which is its smallest unit serves as packets of light. Each of it carries a fixed amount of energy that determines the amount of energy it vibrates thus making the brightness of light dependent on its number. Wavelength, measured in nanometers (nm) is the distance moved by a photon during one of its vibrations. The order of colors is determined by the wavelength of light having red with its longest wavelength and violet with its shortest within the visible light. Wavelength is inversely proportional to the energy (Vermaas). Pigments, which colors come from the wavelengths of light it reflects or not absorbed, are the substance that absorbs light (Vermaas). Chlorophyll is the most important light absorbing pigment in plants. It does not absorb light in the green part of the spectrum making its color green (Light wavelength and photosynthesis). Moreover, there are still other pigments that aids photosynthesis (Hershey, 2004). To measure the rate of photosynthesis, this study have measure the carbon dioxide utilized along the process since CO2 with water are the vital molecules that would be transform to oxygen and carbohydrates by photosynthesis (Farabee). Several other factors could have influenced the defiance within our result. This includes other plant elements that stand beyond our control. Deficiency in essential plant nutrients leading to brown or yellow discoloration termed necrosis or chlorophyll loss results in reduced plant area limiting its support to photosynthesis (Farabee). The amount of water available to the plant will affect the rate of photosynthesis because lack of it would close the leaf's stomata blocking the entrance of CO2. Limiting factors that only allows up to maximum amount of photosynthesis prevents its rate from rising above a certain level even if other conditions were sufficient. That explains why increasing the factor such as temperature to a very high level would not increase the rate of photosynthesis upon reaching its particular limit (Farabee). With the failure to control these factors we did not succeed with our assumption. However, with the presented pervious studies that proved that claim, that hypothesis should not be disregarded rather should be further tackled on future research that could omit all possible uncontrollable defiance of the true result. Sources Hershey, D. (2004). Avoid Misconceptions when Teaching about Plants. Actionbioscience.org. Retrieved October 22, 2008 from http://www.actionbioscience.org/education/hershey.html#primer Vermaas, W. An Introduction to Photosynthesis and Its Applications. Arizona State University. Retrieved October 22, 2008 from http://photoscience.la.asu.edu/photosyn/education/photointro.html Farabee, M.J. (2008). Photosynthesis Retrieved October 20, 2008 from http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html Whitmarsh, J., Govindjee. The Photosynthetic Process. University of Illinois. Retrieved October 22, 2008 form http://www.life.uiuc.edu/govindjee/paper/gov.html Light wavelength and photosynthesis. Retrieved Oct 20, 2008 from http://Pleasanton.k12.ca.us/avhsweb/theil/bio/labs/light_photo.html Read More