2001 Volume 42 Issue 2 Pages 65-73
Most of biological experiments on photosynthetic pigments in upper secondary school are limited to their separation by paperchromatography. In this study, I tried to develop teaching materials for students to find the diversity of photosynthetic pigments among plants and infer the process of the evolution from algae to seed plants, through the separation of photosynthetic pigments and observation of their absorption spectra.
Plant materials for this research were Schefflera arboricola (Seed plant), Ulva pertusa (Chlorophyta), Undaria pinnatifida (Phaeophyta), Porphyra yezoensis (Rhodophyta). To improve the extractive efficiency of photosynthetic pigments, the algae were dried in the dark for about half day. The plant materials were ground with powder of dried silica gel. The fat-soluble photosynthetic pigments were extracted with diethyl ether, while water-soluble pigments were extracted with 10% NaCl solution. Then, fat-soluble photosynthetic pigments were analyzed by TLC using silica gel aluminum plate. Their absorption spectra were observed by a devised simple apparatus. Using this apparatus, the spectra were observed as dark line (region). Separated pigments (Chl.a, Chl.b, fucoxanthin, phycobiliprotein) showed their characteristic absorption spectra. A series of this experiment is very useful for students to find the diversity of photosynthetic pigments among various plants and to relate it to the plant evolution from algae to terrestrial seed pants.
