Observing Differences in Light Intensity and the Photosynthetic Rate while Calculating the Rf Values of Certain Chloroplasts Using a Spectrophotometer and the Value of Absorption
Jacob Kluth and Kelsey Jankowski
Introduction
This lab was intended to educate the AP Biology students of Rf values, how to find transmittance from a substance through a spectrophotometer and about plant pigments such as chlorophyll. Overall, this lab helped the AP Biology students learn about the process of photosynthesis.
Plant pigments are extremely important to plant growth. The pigments absorb sunlight to gather the energy needed for daily functions. Chlorophyll, the main plant pigment, uses the energy acquired to synthesize carbohydrates from CO2 and H2O. The pigment is what creates the fresh green coloring to the plant. Chlorophyll appears green because the pigment absorbs red and blue light and reflects green light. There are two main types of Chlorophyll; named Chlorophyll A and Chlorophyll B. These two types are similar, however, they differ in composition- Chlorophyll A is CH3 and Chlorophyll B is CHO. The pigment is called a photoreceptor and is found in chloroplasts. Chlorophyll must attach to the backbone of a complex protein to function properly.2 This pigment also plays a large role in the process of photosynthesis. Photosynthesis is a process that converts light energy to chemical energy and stores that energy in the plant. The process occurs in the leaves of plants. In 1780, Joseph Priestly found that plants could produce oxygen for other organisms to use. He came about to this conclusion by using a mint leaf, an upturned glass jar, and a candle. The chemist placed the plant and candle into the jar and found that the candle kept burning out due to the oxygen supply from the plant. Jan Ingenhousz discovered that light played a major role in photosynthesis. The chemical equation for photosynthesis is 6CO2+6H20®C6H1206+6O2; where six carbon dioxide and water...