Effects of the Light Wavelengths Pea Germination - Essay Example

? Effects of the Light Wavelengths Pea Germination This paper explores the role of light wavelengths during plant germination of which in this case the pea seedlings were used. Sunlight is very critical for the process of photosynthesis as it‘s the driver of the process. The light wavelengths come in a spectrum form in which the different light wavelengths are absorbed differently by the leaves during the process of photosynthesis. In this sense, there are specific light wave length that accelerates photosynthesis than the rest. It is therefore expected that the different response in growth when the same plants are provided with every requirement similar except the light wavelength is a justified occurance. The difference in light wavelength is possible by use of light filter papers that will only select required wavelength. The experiment done and that forms the basis of this paper is a reflective of the phenomenon. Five pots were used to grow the pea in different light wavelength and then the masses of the pea in the different pots taken. The plants were then placed in an oven (80 degrees centigrade) and the masses of the dry weight of the pea observed and weighed. The results of the experiment show the different activities of the light wavelength on chlorophyll element of the plant, which is responsible for the absorption of light for photosynthesis. Introduction The main aim of the experiment is to ascertain the portion of the light spectrum that is absorbed the most in the leaves by chlorophyll. Apparently, it is known that the light wavelengths are best absorbed at the red and blue region (Toole, Toole, & Toole 1999, p. 132). The light wavelengths are measured in units called Nano meters (nm). In this case, the light wavelengths are best-absorbed 670nm and 500nm in the red and blue region respectively (Mauseth, & Mauseth 2009, p.92). It is therefore hypothesized that much growth occurred in the pots with the red and blue wavelength. Plants grown in the green wavelength environment are therefore expected to poorly perform since they are poorly absorbed to facilitate the process of photosynthesis. At this point of light wavelength absorption, the chlorophyll a and b are responsible for the absorption. There are other accessory pigments that helps absorb light wavelengths that do not fall within the active wavelength. An example of these accessory pigments the carotenoid (Mauseth, & Mauseth 2009, p. 98). The diagram below shows the absorption of light wavelength in the spectrum by the chlorophyll. (McDonald 2003, p. 116) Methodology Since the aim of the experiment was to establish the effects of the light wave length on germination of the pea plant, several batches of the plant were taken and simultaneously grown in the different light wavelengths. These included the red light, the green light, white light and the rest grown in the dark. The white light in this case was used as the control for the experiment. After germination of the pea, a close and careful observation of the seedlings was done and the salient features noted. In the batches of the pea that were grown in the different light wavelength, Vertical heights of the five tallest seedlings were taken and the average taken. Precision was taken to ensure that the measurement reflects the accurate length of the seedlings-measurement was started at the vermiculite/soil level. The seedlings in the white pot whose average was found were then taken out of the pot. The process was done carefully to ensure that no disturbances were caused on the roots of the plant. Any vermiculite/soil that was left on the roots were also carefully removed. A labeled piece of red paper was then placed in the tare key to set the zero balance, this was particularly important in ensuring that the precise weight of the seedlings was recorded. The five seedlings from each of the pots with the peculiar wavelength were taken through the procedure and finally weighed and the units recorded-this was regarded as taking the wet weight of the seedlings. The seedling after taking the weight were taken to an oven at 80?C and left for one week after which they were once more weighed and the masses recorded. All the three aspects measured were then recorded for further interpretations. Results of the experiment The finding of replicate # 12 was compared vis a vis the average for the whole groups. Regarding this, the average was found and the information presented as shown below. The above graph is the illustration of the heights of the pea in the different light wavelengths. The blue bar represents the average of the 16 replicates while the red one is for the trial 12 pea The above graph shows the comparison of the fresh weight of the pea after germination, the blue bar and the red bar represents the average mass of the replicates and the mass of trial 12 respectively The dry mass of the average and that of group 12 are represented in above diagram with the blue and the red indicating the mass of average of the replicates and trial 12 respectively. Discussion of the results Normally plants respond differently to the different light wavelengths. The light wavelengths assume the rainbows colors and these colors are absorbed differently by the plants (McDonald 2003, p. 144). The photosynthetic cells in the plants consist of the chlorophyll which is found in the chloroplast of the plant. The chlorophyll is also divided into two; the chlorophyll a, and chlorophyll b and c these absorbs light at the wavelengths, these occurs at 400-700nm for the chlorophyll a, 500-600nm in chlorophyll b and chlorophyll b is a rare type (McDonald 2003, p. 157) . There are other pigments that are of use when there is no chlorophyll, these are called accessory pigments and include, carotenoids and phycobilins. These accessory pigments assist in furthering photosynthesis in the event that chlorophyll is missing. Photosynthesis is the energy process in which the plants sustain their physiological processes. Through photosynthesis, the plants are able to make carbohydrates on their own and utilize it to run their physiology (Nobel 2009, p. 99). The process of photosynthesis is a complex process that involves electron transfer to finally give the glucose (carbohydrates) - this process is discussed in the introductory part of this paper. The results of the experiment can therefore be interpreted as follows; Height of the plants The heights of the pea plants in the dark region were seen to be relatively taller than the rest due to etiolation. Etiolation is the process by which there is abnormal increase in the vertical height of the plant as the plant uses their reserve food strenuously since photosynthesis cannot proceed in the absence of light (Nobel 2009, p. 111). The pea grown in the blue, red and green region showed higher growth than those of the white light-there was much photosynthetic process as they are abundantly received in the chlorophyll. Fresh weight The fresh weight of the peas that were grown in the sensitive light to chlorophyll gave much fresh weight than those grown in the dark. This is because they were able to make more carbohydrates and increase in weight unlike those in the dark that had to use their reserve to sustain light hence losing weight. This was directly replicable for the dry weight of the plant after the experiment. The results of these experiment resonate with the hypothesis of the study that plant in the sensitive wavelengths are likely to have greater mass than those grown in the dark or in the wavelengths that are not sensitive to light. In scientific experiments, the accuracy and precision can be enhanced by using a large sample size. This is particularly important in spreading the error margin. Conclusion Ideally plants are sensitive to the red and blue region of the spectra for photosynthesis purposes. But in the event that non-green plants are used, the reasonable increase in the mass may not be significant due to the absence of the chlorophyll that will be absent in such plants-this will particularly happen if they are restricted to blue and red light wavelengths which can only be detected by the chlorophyll. References Mauseth, J., & Mauseth, J. D. (2009), Botany: an introduction to plant biology (4th ed.), Sudbury, Jones and Bartlett Publishers. McDonald, M. S. (2003), Photobiology of higher plants. Chichester, John Wiley & Sons. Nobel, P. S. (2009), Physicochemical and environmental plant physiology (4th ed.), Amsterdam, Academic Press. Toole, G., Toole, S., & Toole, A. G. (1999), New understanding biology for Advanced Level (4th ed.), Cheltenham, Stanley Thornes. Read More