2. A pigment solution contains compound A with 4 polar groups and compound B with 2 polar groups. You plan to separate these compounds using paper chromatography with a non-polar solvent. Predict the location of the two bands relative to the solvent front. Explain your answer.
Since compound A is probably more polar than compound B, compound B will move further in the chromatography. Since the solvent is non-polar, the less polar compound will be more soluble in the solvent than the more polar one.
Applying Your Knowledge
2. In response to shortened day length and cool temperatures in the fall, many trees begin a period of senescence when the breakdown of chlorophyll exceeds a chlorophyll production. The leaves of these trees appear to change to yellow and oranges. Using your knowledge of photosynthetic pigments, explain the source of these yellow-orange hues. The carotenoids, which are the pigments that reflect in the yellow to red spectra and absorb blue light. There are some, functioning as secondary pigments involved in photosynthesis, that is unmasked once the chlorophyll content diminishes.
3. Duckweed is a tiny floating aquatic plant that can reproduce so rapidly that it can completely cover the surface of small fish hatchery ponds. One proposal to limit the growth of this invasive plant is to use colored panels to shield the ponds, inhibit photosynthesis, and kill this pest. What color filters would you order for the panels in this project? What wavelengths of light will be absorbed by theses filters? So you think this proposal will be effective in killing the duckweed? Primary photosynthesis occurs in the red and blue regions of the visible light spectrum. By inhibiting light passage for wavelengths of 700-635nm and 490-450nm, most photosynthesis would become inefficient. This would most likely kill the pest as well as most other primary photosynthetic life.