Measuring the Rate of Photosynthesis Using a Spectrophotometer
Spectrophotometer Lab:
Length: 1437 words (4.1 double-spaced pages)
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Spectrophotometer Lab
Introduction:
A spectrophotometer is an instrument that measures the quantitative amounts of light of different wavelengths absorbed and transmitted by a pigment solution (Mitchell, Reece). The spectrophotometer includes a light bulb, a reflector, and a detector. When a sample is in place and the chamber lid is closed, light from the light bulb passes through it. The detector measures the amount of light transmitted. The white light from the bulb is separated into different wavelengths by reflecting the beam off of a diffraction grating, forming a spectrum.
A mirror is used to control the angle at which the light is reflected, so light of a single wavelength can be passed through the sample. A pigment solution (such as spinach and acetone) is exposed to different wavelengths of light to determine the points of the highest absorbance and transmittance percentages. (Hickey, Mary Kay). For this experiment, a Bausch and Lomb Spectrophotometer was used. Often objects appear colored because of their absorption of light within regions of the visible spectrum. The color of light we can see is composed of the wavelengths that the object did not absorb.
Photosynthesis in plants takes place in organelles called chloroplasts. Chloroplasts contain a number of coloured compounds, known as pigments, in their thylakoids, where light dependent reactions occur(Mitchelsl, Reece). Spinach leaves contain chlorophyll a and b and b -carotene as major pigments as well as smaller amounts of other pigments such as xanthophylls. The two forms of chlorophyll are identical except that a methyl group in a is replaced by an aldehyde in b. In terrestrial plants, the most important pigments are chlorophyll a (blue-green), chlorophyll b (yellow-green), xanthophyll
(yellow) and carotene
Length: 1437 words (4.1 double-spaced pages)
Rating: Red (FREE)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Spectrophotometer Lab
Introduction:
A spectrophotometer is an instrument that measures the quantitative amounts of light of different wavelengths absorbed and transmitted by a pigment solution (Mitchell, Reece). The spectrophotometer includes a light bulb, a reflector, and a detector. When a sample is in place and the chamber lid is closed, light from the light bulb passes through it. The detector measures the amount of light transmitted. The white light from the bulb is separated into different wavelengths by reflecting the beam off of a diffraction grating, forming a spectrum.
A mirror is used to control the angle at which the light is reflected, so light of a single wavelength can be passed through the sample. A pigment solution (such as spinach and acetone) is exposed to different wavelengths of light to determine the points of the highest absorbance and transmittance percentages. (Hickey, Mary Kay). For this experiment, a Bausch and Lomb Spectrophotometer was used. Often objects appear colored because of their absorption of light within regions of the visible spectrum. The color of light we can see is composed of the wavelengths that the object did not absorb.
Photosynthesis in plants takes place in organelles called chloroplasts. Chloroplasts contain a number of coloured compounds, known as pigments, in their thylakoids, where light dependent reactions occur(Mitchelsl, Reece). Spinach leaves contain chlorophyll a and b and b -carotene as major pigments as well as smaller amounts of other pigments such as xanthophylls. The two forms of chlorophyll are identical except that a methyl group in a is replaced by an aldehyde in b. In terrestrial plants, the most important pigments are chlorophyll a (blue-green), chlorophyll b (yellow-green), xanthophyll
(yellow) and carotene
References: 1. Campbell Neil, Reece Jane, Mitchell Lawrence, 1996. BIOLOGY-Fifth edition 2. Buchanan, B.B., Gruissem, W., and Jones, R.L. 2002