Analysis of the Absorption of Green Light Versus Red Light Absorption in Spinach Leaves
The goal of the experiment was to determine if green light had less ability to absorb than red light in spinach leaves. This was done by separating the photosynthetic pigments (chlorophyll a, chlorophyll b, carotene and xanthophylls) from one another using paper chromatography. The separated pigments were then analyzed for their absorption spectrum using a spectrographometer. When the data was graphed it clearly showed the higher rate of red light absorption over green light. These results along with previous research indicate the importance of red light in photosynthesis and the minor role green light plays.
The majority of life on Earth depends on photosynthesis for food and oxygen. Photosynthesis is the conversion of carbon dioxide and water into carbohydrates and oxygen using the sun’s light energy (Campbell, 1996). This process consists of two parts the light reactions and the Calvin cycle (Campbell, 1996). During the light reactions is when the sun’s energy is converted into ATP and NADPH, which is chemical energy (Campbell, 1996). This process occurs in the chloroplasts of plants cell. Within the chloroplasts are multiple photosynthetic pigments that absorb light from the sun (Campbell, 1996).
Photosynthetic pigments work by absorbing different wavelengths of light and reflecting others. These pigments are divided into two categories primary (chlorophyll) and accessory (carotenoids) pigments. Chlorophyll is then divided into three forms a, b, and c (Campbell, 1996). Chlorophyll a is the primary pigment used during photosynthesis (Campbell, 1996). This pigment is the only one that can directly participate in light reactions (Campbell, 1996). Chlorophyll a absorbs the wavelengths of 600 to 700nm (red and orange) along with 400 to 500nm (blue and violet) and reflects green wavelengths (Lewis, 2004). Chlorophyll b has only a slight difference in its structure that causes it to have a different absorption spectra (Campbell, 2004). The carotenoid involved with spinach leaf photosynthesis absorbs the wavelengths of 460 to 550nm (Lewis, 2004). The pigments are carotene and its oxidized derivative xanthophylls (Nishio, 2000). A wavelength is determined by measuring from the crest of one wave to the crest of the next wave. All the wavelengths possible are...
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520 0.06 0.049 0.01 0.005 0.09
540 0.06 0.06 0.01 0 0.088
560 0.08 0.065 0.01 0 0.09
580 0.125 0.076 0 0 0.111
600 0.15 0.091 0 0.005 0.122
620 0.21 0.09 0 0.005 0.148
640 0.24 0.3 0 0.005 0.195
660 0.99 0.18 0.01 0.01 0.495
680 0.18 0.03 0 0.01 0.09
700 0.03 0.01 0 0 0.028
720 0.01 0.01 0 0 0.02
Figure 2: The absorabancy spectrum shows how absorbent the photosynthetic pigments are at different wavelengths of light. Note: Green light is between 500 to 570 nm and red light is between 630 to 720 nm.
References
Campbell, N.A., “Biology,” New York: The Benjamin/Cummings Publishing Company, Inc., 1996, 182-200.
Karohl, D., “Principals of Biology I Laboratory,” Lorain, Lorain County Community College, 2003, 65-71.
Lewis, R., “Life,” Boston: McGraw-Hill , 2004, 97-114.
Nishio, J.N., “Why are higher plants green? Evolution of the higher plant photosynthetic pigment complement,” Plant, Cell and Environment, 2000, 23, 539-5
Charter Schools are best known for combining traits and features of both public and private schools. Charters schools are not restricted to many of the rules and policies put on other public schools (Gale 1). For example teachers are given more free reign in charters, and they are not expected to stick to a certain curriculum. Because there is no specific criteria in place for teachers of charter schools, pay scales do not have to be followed for teachers and administrators. Also, charters are publically funded and have specialized accountability for producing certain results.
Plants can absorb and use light energy because they have a green pigment, chlorophyll, contained in the chloroplasts in some of their cells. Chlorophyll allows the energy in sunlight to drive chemical reactions. Chloroplasts act as a energy transducers, converting light energy into chemical energy. So as the plant has more light the chlorophyll inside the chloroplasts can react faster absorbing in more light for food and energy.
The high rate of absorbance change in blue light in the chloroplast samples (Figure 1) can be attributed to its short wavelength that provides a high potential energy. A high rate of absorbance change is also observed in red light in the chloroplast samples (Figure 1), which can be accredited to the reaction centre’s preference for a wavelength of 680nm and 700nm – both of which fall within the red light range (Halliwell, 1984). Green light showed low rates of photosynthetic activity and difference in change in absorbance at 605nm in the chloroplast samples (Figure 1) as it is only weakly absorbed by pigments, and is mostly reflected. The percentage of absorption of blue or red light by plant leaves is about 90%, in comparison to the 70–80% absorbance in green light (Terashima et al, 2009). Yet despite the high absorbance and photosynthetic activity of blue light, hypocotyl elongation was suppressed and biomass production was induced (Johkan et al, 2012), which is caused by the absorption of blue light by the accessory pigments that do not transfer the absorbed energy efficiently to the chlorophyll, instead direction some of the energy to other pathways. On the other hand, all of the red light is absorbed by chlorophyll and used efficiently, thus inducing hypocotyl elongation and the expansion in leaf area (Johkan et al, 2012).
Although about 2 million American students now attend around 5,600 charter schools, I do not think this as beneficial to American students as charter school proponents claim. Despite all of the “perks” charters schools boast of and attract parents with, these schools do not necessarily perform better than average schools. Charter schools give an unfair advantage to stronger students, leaving students who struggle in weaker schools with fewer resources to help them. Perhaps most importantly, they are not available to all students, even though they are funded by public tax dollars. Although the motivations behind charter schools are admirable, they are not worth it. Our efforts in improving education are better spent investing in the public schools we already have.
Charter schools are public schools, but can be a better option than traditional public schools for some students. By definition, a charter school is a publicly funded and privately run school under the charter of an educational authority. (2-4) A charter school is held to a different set of standards than most traditional public schools. This can often work towards their advantage because it allows them to try new and unique methods of educating children. And the education system could use some fresh ideas.
In a nation dominated by capitalism and free trade, steps are being taken to turn the ability to learn and other education rights into commodities that can be manipulated and controlled by companies. Charter schools are public schools funded by state money, but not unionized; they also can be in the form of a traditional brick and mortar schoolhouse or an online school (Ravitch)(Molnar)(“Preface to 'Are Charter and Magnet Schools Good Alternatives for Students?’”). According to their proponents, charter schools allow parents more sway over their child’s education (Jacoby 77). A charter school proponent Jeff Jacoby states, “Their goal: to build the kind of school that used to be commonplace in America-one providing a rigorous, traditional, fact-based
Public and charter schools may look to be the same, but charter schools differ in many ways and have an interesting origin that is often overlooked. The concept of charter schools began in New York City around the late 1980s and early 1990s by a man name Albert Shanker. They were originally created to be teacher-run schools that would provide education and services to students struggling in the traditional school system (Karp, 2013). These schools had operated outside the administrative bureaucracy and the big city school board. Shanker initial concern was that these small charter schools were dividing the district by serving a different population with unequal access as well as weakening the power of teacher union in negotiation over district-wide policies and regulations (Karp, 2013). Because of this Shanker withdrew his support, but charters had continued to grow and states were ...
Zimmer, R. and Buddin, R. (2009), Is Charter School Competition in California Improving the Performance of Traditional Public Schools?. Public Administration Review, 69: 831–845. doi: 10.1111/j.1540-6210.2009.02033.x
Cerjak ,The English Journal, Vol. 76, No. 5 (Sep., 1987), pp. 55-57 Published by: National Council of Teachers of English
Conclusion- The data supports my hypothesis. By looking at the graph titled “Average Rate of Photosynthesis” we see massive photosynthetic activity occurring from :30 to 10:00 with particularly impressive growth occurring in red and blue light around the 5:00 and 8:30 respectively. The colors that have the highest influence on photosynthesis is blue and red. This is also why so many gardeners both amateur and professional alike use blue and red lights to grown plants. Under red light, all discs floated before the tenth minute. This was also observed with blue light. The graph shows that green had the least successful photosynthetic rate, whereas red, blue and regular natural light had the most successful photosynthetic rate. Photosynthesis involves converting light energy in chemical energy through the use of photosynthetic pigments like chlorophyll. Light from the sun is comprised of different colors, sometimes referred to as wavelengths. My data matches research conducted by other scientists: chlorophyll absorbs red and blue light more than green. The green light is instead reflected making the leaves appear green. Green light experienced almost no photosynthesis throughout the entire experiment at any time. Almost no discs floated to the top at any point. Yellow, interestingly, was an outlier. I will discuss this further in the “Limitations of Experimental Design” section.
Crystal, David. The English Language: A Guided Tour of the Language. London: Penguin Books, 2002
The system involved in this lab was L-dopa as a substrate, enzyme was Tyrosinase, and the product was Dopachrome. Tyrosinase is commonly known as polyphenol oxidase, an enzyme that present in plant and animal cell (#1 Boyer). In plant cell, the biological function if Tyrosinase is unknown, but its presence is readily apparent. Tyrosinase is also involved in the browning of fruits, tubers, and fungi that have been damaged. In mammalian cell, Tyrosinase is involved in melanin synthesis, which gives skin its color. It will act on the substrate L-dihydroxyphenylalanine (L-Dopa) and convert to Dopachrome, which is the product that has color, and it can measure at 475nm using the Spectrophotometer. This work based on the Beer-Lambert’s Law (A=εlc), A stands for Absorbance, ε is extinction coefficient or the molar absorptivity (M-1 cm-1), and l is the path length (distance) that light passes through the sample (cm), c is a concentration of solution (M) (#3 Ninfa, Ballou, Benore). Beer- Lambert Law predicts a linear relationship between absorbance and the concentration of a chemical species being analyzed. It states that the absorbance (A) of a sample solution is directly proportional to the concentration (c) of the absorbing colored
Light is a very important factor in the rate of photosynthesis, in my project I am going to test that plants do need light in order to photosynthesise. It will be very interesting to see how light will influence the rate of photosynthesis in plants and what will happen if they do not get the required light in order to produce starch .
The structure of chlorophyll involves a hydrophobic tail embedded in the thylakoid membrane which repels water and a porphyrin ring which is a ring of four pyrrols (C4H5N) surrounding a metal ion which absorbs the incoming light energy, in the case of chlorophyll the metal ion is magnesium (Mg2+.) The electrons within the porphyrin ring are delocalised so the molecule has the potential to easily and quickly lose and gain electrons making the structure of chlorophyll ideal for photosynthesis. Chlorophyll is the most abundant photosynthetic pigment, absorbing red and blue wavelengths and reflecting green wavelengths, meaning plants containing chlorophyll appear green. There are many types of chlorophyll, including chlorophyll a, b, c1, c2, d and f. Chlorophyll a is present in all photosynthetic organisms and is the most common pigment with the molecular formula C55H72MgN4O5. Chlorophyll b is found in plants with the molecular formula C55H70MgN4O6, it is less abundant than chlorophyll a. Chlorophyll a and b are often found together as they increase the wavelengths of light absorbed. Chlorophyll c1 (C35H30O5N4Mg) and c2 (C35H28O5N4Mg) are found in algae, they are accessory pigments and have a brown colour. Chlorophyll c is able to absorb yellow and green light (500-600nm) that chlorophyll a
Ypsilandis, G.S. & Kantaridou, Z., (2007). English for Academic Purposes: Case Studies in Europe, Revista de Linguistica y Lenguas Aplicadas (2): 69-83.