Light Absorption by Photosynthetic Pigments in Silver Beet
The aim of the experiment was to determine the absorption of differing wavelengths of light by individual pigments in the vegetable silver beet. Pigments were extracted from silver beet leaves and separated into chlorophyll a, chlorophyll b, and carotene via chromatographs. Chlorophylls were then separated and an absorption spectra created using results obtained from a spectrophotometer. It was clear there were two distinct peaks in the graphical representation of the results. This is consistent with absorption spectra graphs present in (Knox et al., 2005), refer to appendix. Introduction
Like all living organism on Earth, plants must harvest energy to survive. Plants do this by converting solar energy and storing it in the chemical bonds of ATP and carbohydrates, a process called photosynthesis (Knox et al., 2005). However, this report is only concerned with photosynthetic pigments and what wavelength of light they absorb, rather than the process of photosynthesis itself. Chlorophyll is a green, light absorbing pigment found in plants which allow them to utilise the energy in light to survive. This is because chlorophyll is the main pigment associated with photosynthesis. Chlorophyll a is the main type of light absorbing pigment found in plants. However chlorophyll b is also present in some plants (including silver beet) along with carotenoids which is another type of photosynthetic pigments which can absorb light over a large range of the visible spectrum (Knox et al., 2005). This experiment investigated the absorption of different wavelengths of light in chlorophyll a, chlorophyll b and carotene. The aim of the experiment was to create absorption spectra for each photosynthetic pigment chlorophyll a, chlorophyll b and carotene, and investigate any relationship between the absorption of light and the rate of photosynthesis at the same wavelengths, using an action spectrum (School of...
References: Giancoli D (1998). Physics. Principle with Applications, 5th edition. Prentice Hall, New Jersey, pp. 731, 829-30.
Knox B, Ladiges P, Evans B, Saint R (2005)
Peat M, Franklin S, Taylor C, Stanbury P (2006b). BIOL1101 Skills for Undergraduates, The University of Sydney, Sydney, pp. 55-57, 63-67.
School of Biological Sciences (2006a). BIOL1101 Laboratory and Lecture Notes, The University of Sydney, Sydney, pp. 42-54
Calculating t-test statistic:
= = 0.0124 (School of Biological Sciences, 2006b)
= = 0.0066 (School of Biological Sciences, 2006b)
The pooled variance (S2) is:
= = 0.0032 (School of Biological Sciences, 2006b)
= 5 (School of Biological Sciences, 2006b)
Absorption spectra from existing literature
Knox B, et al. (2005). Biology. An Australian Focus, pp. 116 figure 5.12
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