UV-Visible Spectroscopy. Visible and Ultraviolet Spectroscopy 1. Background An obvious difference between certain compounds is their color. Thus, quinone is yellow; chlorophyll is green; the 2,4-dinitrophenylhydrazone derivatives of aldehydes and ketones range in color from bright yellow to deep red, depending on double bond conjugation; and aspirin is colorless. In this respect the human eye is functioning as a spectrometer analyzing the light reflected from the surface of a solid or passing through a liquid. When white light passes through or is reflected by a colored substance, a characteristic portion of the mixed wavelengths is absorbed. 2. The visible spectrum constitutes but a small part of the total radiation spectrum. The energy associated with a given segment of the spectrum is proportional to its frequency. 3.
The visible region of the spectrum comprises photon energies of 36 to 72 kcal/mole, and the near ultraviolet region, out to 200 nm, extends this energy range to 143 kcal/mole. 4. What Wavelength Goes With a Color? Colors We Can't See There are many wavelengths in the electromagnetic spectrum the human eye cannot detect. Energy with wavelengths too short for humans to see Energy with wavelengths too short to see is "bluer than blue". Light with such short wavelengths is called "Ultraviolet" light.
How do we know this light exists? One way is that this kind of light causes sunburns. Energy with wavelengths too long for humans to see Energy whose wavelength is too long to see is "redder than red". How do we know this kind of light exists? Very long wavelengths of infrared light radiate heat to outer space. Measuring the Rate of Photosynthesis with the Floating. (A resource page) Brad Williamson Introduction: Trying to find a good, quantitative procedure that students can use for exploring photosynthesis is a challenge. The standard procedures such as counting oxygen bubbles generated by an elodea stem tend to not be “student” proof or reliable. This is a particular problem if your laboratory instruction emphasizes student-generated questions.
Over the years, I have found the floating leaf disk assay technique to be reliable and understandable to students. The biology behind the prodedure: Leaf disks float, normally. Materials: Sodium bicarbonate (Baking soda) Liquid SoapPlastic syringe (10 cc or larger)—remove any needle! Leaf material Hole punch Plastic cups Timer Light source Optional: Buffer Solutions Colored Cellophane or filters Leaf material of different ages Variegated leaf material Clear Nail polish Procedure: Prepare 300 ml of bicarbonate solution for each trial. Add 1 drop of dilute liquid soap to this solution.
Avoid major veins. Minutes Disks Extension: FloatingLeafDiskPhotosynthesisLab.pdf (application/pdf Object) Leaf Floating Techniques. Floating Leaf Disc Photosynthesis Lab 1213.pdf (application/pdf Object) Color & Light Effects on Photosynthesis. Affect of Different Colored Lights on Photosynthesis. Effect of Different Colored Lights on Photosynthesis Anastasia Rodionova, Cassidy Davis, Sara Cucciniello CU Boulder, Fall 2003 Our experiment tested which color (red, blue, green) would influence the plant to produce the most amount of photosynthesis. There are four main photosynthetic pigments found in the chloroplast of the plant called chlorophyll a, chlorophyll b, xanthophylls, and carotenes.
All these pigments absorb light and possibly utilize the light energy in photosynthesis. Light energy is essential for photosynthesis. To test this we used about 5 grams of leaves for each trial, and placed them in a gas chamber. Our results showed the least amount of CO2 under blue light (mean: -8.1 ppm/min/g), medium amount in the red light (mean: -1.04 ppm/min/g), and the most amount in the green light (mean: 4.7 ppm/min/g). Our results are contradictory with our hypothesis, based on our statistical results. BiologyGuide: A Level Biology Revision Notes. An On-Line Biology Book.