The oligohymenophrous ciliate Paramecium bursaria has endosymbiotic chlorella. P. bursaria shows positive phototactic response, and its response was used as teaching materials. Although the heterotrichous ciliate Stentor polymorpus also has endosympiotic chlorella same as P. bursaria, it has notbeen reported about its phototactic response and its application as teachingmaterials. In this work, we examined whether S. polymorphus can be used as teaching materials by investigating the relationships between the existence of endosymbiotic and the host's phototactic response.
when, cultivating S. polymorpus in light, they showed positive phototactic response. Then, cultivating them in the dark, they indicated thenegative response. Moreover, stentors showed positive phototaxis if they had beenkept in the light environment for one day even after being grown in dark. The position and number of its chlorella were also found to change at the conversion of culture condition. These results suggest that the closely relateto their host's phototactic response, and S. polymorpus is applicable as a teaching material in school education.
We developed a culture system of Osmunda banksiifolia (Pr.) Kuhn with the lowest chromosome number of 2 n = 44 among Filicales and examined its usefulness as a teaching material.
On the 1/2 Murashige-Skoog (MS) agar medium, spores germinated within a week. Sexual organ matured and fertilized within 7 months and young sporophytes were formed within 8 months. Then, young sporophyte was transplanted onto 1/4 MS agar medium in a flask and cultured continuously. After 4 months of transplantation, sporophyte formed fertile fronds. The frond formation repeated about ten times in a year.
For the observation of cell division, young roots and young sporangium of sporophytes were used. In the mitotic cell division of root tip, we could count 44 chromosomes at metaphase stage. In the meiotic cell division of spore mother cells, we could count 22 bivalent chromosomes (2n = 44 = 22 II) at metaphase I.
These results show the usefulness of culture system of Osmunda banksiifolia as a teaching material for the topics of “Cell”, “Reproduction and Development” and others in the biology class of the secondary schools.
The portable telephones are now used commonly by students in secondary schools.
Usingpotable telephone while walking or riding on a bicycle, however, is one of the causes of traffic accidents. In order to raise the awareness of this danger in biology classes as a form of safety education, we applied an experiment on bar-gripping reaction time to a series of experiments for inquiring the delay of human’s reaction. This applied investigation consists of one basic experiment for getting baseline data and five experiments for inquiring the effects of seeing, hearing and thinking on bar-gripping reaction time. These experiments were conducted to university students. The average baseline value of bar-falling distance was 29.43cm, and this means that reaction takes nearly 0.25 seconds.
Compared with this baseline data, the rate of failure of bar-gripping increased 4-5 times in the other experiments in which subjects were given a second task such as calculating and reading. The examinees could not grip a bar every two trials on the average when they were told to look for mistakes or differences in a picture. This line of experiments was adapted to create an activity for safety education in high school biology. High school students taking this class devised original methods for inquiring the delay of human’s reaction. Questionnaire results to these students showed that more than half of them enhanced their awareness of the appropriate use of the portable telephone.