Ideally, a teacher would have no more than twenty four students to coach through this activity. A student will have prior knowledge as to the equation describing the photosynthetic process as well as having a basic understanding of the scientific method.
Make a chromatogram strip.
The tapered part the point should be 1 inch long. Obtain a capillary tube and load it by dipping it in chlorophyll acetone solution spinach leaves boiled in acetone to extract the chlorophyll from their chloroplasts.
The solution will be drawn up into the tube by capillary action. Draw a light pencil mark in the center of the strip where the tapering ends one inch above the point. Load the chromatogram with chlorophyll solution. Touch the paper on the dot with the glass capillary tube to release a drop of chlorophyll solution.
Wait until the drop dries, and then repeat over the same positions you made previously. Repeat this process until 40 drops have been added. Add 3 ml of petroleum ether: Carefully place the filter paper, point downward, into the petroleum ether chloroform solution.
Be careful not to touch the sides of the tube with the filter paper, and make sure that the spot of extract is above the solvent level. If it falls below, the spot will rinse off. Seal the tube with a stopper and run the chromatogram upright at room temperature. Allow the paper to air dry. You should be able to observe four bands of color pigments.
These bands will represent: Which pigment is the most soluble, and which is the least soluble? How did you reach these conclusions? Calculate an Rf for each pigment. The ratio of the distance traveled by the dissolved substances to the distance the solvent moves is known as the rate of flow Rf.
Each substance has a characteristic Rf value in a specific solvent and under specific conditions. It may be altered by factors such as concentration of solute, temperature, pH, etc.
It mainly absorbs energy in the red and blue areas of the spectrum. The other bands of light pass through unaffected, or are reflected, giving the characteristic green color to the leaves. The relative absorption of different wavelengths of light by a pigment is represented by an absorption spectrum.
In this exercise you will plot an absorption spectrum for the spinach leaf pigments that are available. This will be done by the determination of the absorbance at different wavelengths on a spectrophotometer. Place the ethyl alcohol blank in the machine. When placing the spec tube in, be sure to clean the tube with a kimwipe and align the arrow on the top of the tube so it faces you.
Close the cover and zero the blank. The machine is now set and ready to take a reading at nm this is the maximum absorbance of chlorophyll. If this point is on scale, all other values will also be on scale. Insert the chlorophyll sample and read the transmittance. This will ensure that all readings taken over the range of wavelengths from to nm will remain on scale.
You will take readings of light absorbency of the chlorophyll extract at 15 nm intervals, starting at nm and going through nm. The machine must be zeroed with the alcohol blank each time the wavelength is changed. After you have made all your readings and translations you should plot the points on a graph and connect them with a smooth curve.
Get a signature from the TA for your raw data. Two principal reactions of photosynthesis proceed only in the presence of light.A Spectrophotometric 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.
Students conducted an experiment to determine the effect of light intensity on the rate of photosynthesis. They punched 40 leaf disks from spinach leaves and used a syringe partially filled with water to pull the gases from the leaf disks so that all leaf disks sunk to the bottom of the syringe.
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.
A Spectrophotometric 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.
A Spectrophotometric 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. The cones can detect either red, green or blue light.
Thus, our ability to see color is through stimulation of one or more cones. Extract and identify the various photosynthetic pigments from spinach leaves.
2. Determine the ABSORPTION SPECTRUM of these spinach chloroplast pigments. 3. Determine the ACTION SPECTRUM of spinach chloroplasts.