Development of laboratory exercises for studying "Plant growth and morphogenesis" in upper secondary school biology.

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After analyzing the present biology textbooks prepared for the secondary level, we concluded that not enough laboratory exercises are offered for the students to study plant growth and morphogenesis. Our research project was organized to develop laboratory exercises which are both simple and useful for studying these topics in upper secondary school biology. The research included the exploitation of teaching materials, examination of experimental conditions and simplification of experimental procedure or apparatus.Two modules, "Effect of cytokinins on the greening and swelling of the excised etiolated cucumber cotyledon" and "Detection of ethylene evolved from ripening fruits by use of an evergren twig" seem to be useful for studying the action of plant growth substances. The other three modules, "Sleeping movement of leaflets of Leguminosae - a phytochrome mediating phenomenon' "Effect of light on the uncurling of the epicotyl hook in etiolated kidney bean seedlings" and "Effect of light on the seed germination", seem to be useful for studying the effect of light on the plant growth and morphogenesis.For examining the effect of light, the supply of monochrome light is necessary to get a good result. Besides ordinary fluoresent lamps and color filters, we used special kinds of fluoresent lamps which are used for the regulation of photoperiodis in agriculture to obtain different wavelengths of light.Some of the modules listed above were examined in upper secondary school biology classes and their usefulness was confirmed.