Illinois Junior Academy of Science - Yearbook (Urbana, IL)

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Sirepfomycin Vrs. the Formation of Chloroplasts KARYL MCCURDY Thornridge High School lllbll Illllililll -mn in on numnflou 1 ur. JIZTHA 5 NY: D' 'W Pun I Streptomycin was discovered in 1943 by two scientists working to find something effective against tuberculosis. On a more botanical level, I was curious to discover this chem- ical's effect on plant growth. Streptomycin had a bleaching or toxic effect on plant growth. Plants with various mineral deficiencies were also treated with streptomycin, to see how the absence of certain vital nutrients affected streptomycin's effect. My hypothesis concerning streptomycin's harmful effect revolved around one chemical reaction in particular, chela- tion. This is a chemical process in which an organic com- pound would react with a metal ion to form a relatively inert water compound. Magnesium is the central atom in the chlorophyll molecule, so perhaps streptomycin's bleach- ing effect may be explained by streptomycin chelating with the magnesium. This process would remove the magnesium necessary in the formation of the green pigment chlorophyll, thus hindering its formation. To combat this I proposed that the addition of extra magnesium would erase the bleaching effect. The streptomycin could chelate with the extra mag- nesium, thus leaving the magnesium in the nutrient solution for normal chlorophyll synthesis. My results confirmed this, the plants treated with streptomycin and magnesium grew almost as well as the controls. To insure valid results. I dealt with one-hundred and ninety plants representing seven species: beans, corn, peas, radishes, tomatoes, euglena, and chlamydomonas.

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hypothesis that light is one of the main factors determining the time of peak mitotic activity in allium cepa. The hy- pothesis tested in this investigation was: If the natural times of peak mitotic activity are determined by the en- vironmental factor light, a change in the cycle of illumina- tion will alter the time of peak mitotic activity. The experimental design incorporated the cycling of six hours of illumination followed by six hours of darkness for the experimental group. The control group was grown in a natural environment with the cycle of illumination corres- ponding to the times of sunrise and sunset. Root tips were cut at two hour intervals, prepared by a chromosome squash technique, photographed, and the photograps were examined to find the percentages of cells showing mitotic activity. The results of this investigation lends evidence to the original hypothesis that light is one of the main controlling factors in the determination of the times of peak mitotic activity and that a change in the cycle of illumination will alter the times of peak mitotic activity in allium cepa. -,,n-,u,,.u4L, .- 1 vwnuamuiu Radiation: Hazard or Help? DOROTHY MAYR Parkview Junior High School Lawrenceville Sponsor: Miss Haul McKinney ' The purpose of my project was to study the effect of cer- tain types of radiation on certain types of plants and seeds. also to study the absorption of certain radioisotopes by these p ants. I exposed containers of grass, tomato and marigold plants to varying amounts of X-ray radiation and checked their growth. One group received five seconds X-ray each day. One group received one second X-ray each day. One group received one second X-ray once every five days. One received no radiation for a control. I also planted tomato and marigold seeds that had been exposed to various amounts of radiation from 0 to 50,000 roentgens, and checked their growth. The plants derived from irradiated seeds and the plants irradiated while growing grew better than the contral sam- ples. Using a Geiger Counter I measured the absorption of the radioisotopes Pai, Sis, and Ca by tomato and marigold plants through their leaves, roots, and from the soil. I also made auto-radiographs of these plants to study the distribu- tion of the radio-isotopes in the plants. The radio-isotope most readily absorbed was the PS' through the roots of the plants. There was very little ab- sorption through the leaves of the plants. The least amount of difference in growth between the irradiated and control samples was in the grass. I had expected the growth of the treated samples would be less than the control samples. However, in my project it was the other way around: the irradiated samples had more growth than the control samples. The Effects of DNP on 2, 4-D in Soybeans DALE A. NELSON Glenbard East High School Lombard l l Experiments were conducted examining the ability of DNP to uncouple oxidative phosphorylation and thusly count- eract or equalize the growth effects of 2,4-D as an auxin. DNP was shown to equalize 2, 4-D in varying cases. Time intervals between the chemicals were also established as a decisive factor.

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