Ammonia is toxic metabolite generated via deamination of amino acid. Therefore, ammonia is converted to less toxic products such as urea and uric acid in various land animals and cartilaginous fishes. However, teleost fish and most of aquatic invertebrates excrete ammonia directly into their surrounding water from gill and skin. Nitrification, an oxidation process of ammonia to nitrate catalyzed by nitrifying bacteria, plays a critical role to breed fish in good condition. For evaluation of water quality in ornamental aquarium, various ammonia examination kits are sold on the market. In this experiment, we put some ornamental fishes: gold fish (Carassius auratus auratus), Medaka (Oryzais latipes), angelfish (Pterophyllum scalare var.), and coridoras (Coridoras aeneus) in different numbers into each 250 mL of water followed by measurement of ammonia level by using Tetra-test Ammonium. Ammonia was increased to over 1.5 mg/L when 20 of gold fish or 6 of coridoras were put for 10 min at room temperature. All the students could confirm the obvious elevation of ammonia concentration excreted from the gold fish at a lesson of basic biology. We show here that simple examination kit would be appropriate educational material to realize protein-metabolism.
Changes in the aims, objectives, contents of learning, and teaching approaches in American high school zoology during the 19th century were examined in this study. Textbooks and publications of the period, along with literature concerning historical research on American science education, were used for the historical analysis. The textbooks and various historical records that were used in high schools during that time were analyzed. The typical purposes, contents, and methods representative of each time were not found in “zoology” texts; rather, a mixture was observed. Certain changes were found when the texts focused on “humans.” They were a qualitative change of “what to consider as practical”, a shift from the idea of confrontation to that of coexistence, and so on. This is the new discovery that was not in the conventional accepted theory. These changes were interpreted by factors such as the maturity of academics, the influence of society, people’s lives, the surrounding environment, the requirements of students and educational theory.
In junior high school, students are expected to learn through observation the characteristics of sexual and asexual reproduction of living organisms. However, a convenient teaching material that allows an easy and quick observation of the entire process of asexual reproduction has been scarce. Many plants in nature reproduce asexually by regeneration from vegetative organs such as leaves and roots (vegetative reproduction). In this study, we focused on the perennial herbaceous plant Rorippa aquatica (Brassicaceae), aiming to develop an experimental teaching material of asexual reproduction. R. aquatica has a high ability to propagate asexually, and when leaves are cut and placed in a moist place, new plantlets form at the proximal side of leaf fragment that fully regenerate to whole plants. If the moisture is adequate, the whole regeneration process can be observed within two weeks. In this study, we established an efficient vegetative reproduction protocol and observation method of R. aquatica, and carried out educational practice in science classes for third year junior high school students. We conducted this lesson in two parts. In the first class, the students learned about the characteristics of asexual reproduction in potatoes, which is a familiar vegetable. Then, the students cut the leaves of R. aquatica to start vegetative propagation. This was followed by two weeks of observation and all of the students were able to observe the vegetative propagation process. In the second class, after summarizing the observation results, the students discussed the relationship between the living environment, and asexual reproduction of R. aquatica, while paying attention to the inheritance of genes during sexual and asexual reproduction, as well as the differences between parent and offspring traits. From the above results, R. aquatica can be expected to be an effective experimental teaching material for studying vegetative reproduction in junior high school science classes.
Several kinds of colored water which are used to confirm the water transport in the seedling of garden balsam, Impatiens balsamina L., were examined for science classes in primary school. All source matters examined, that is, a colorant of cut flowers, a food color and red ink offered commercially, are effective in as the source of colored water, while the concentration and processing time of each colored water for good results are different among each of them. The colored water of the colorant of cut flowers and the food color reached to the top leaf within 30 min from the start of soaking, while that of red ink needed about one to two hours to reach the top. These results suggest that all color matters examined in the present study are suitable as sources of colored water for use in the science class of primary school with regard to their concentration and processing time.