Germination of Radish Seed

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APES Unit 9 Name___________________________Date__________Period______ The Effects of Radiation on the Germination and Growth of Radish Seeds INTRODUCTION: Gamma radiation is a form of energy similar to X-rays, which, along with other forms of radiation, is emitted from a variety of environmental sources. Two other kinds of radiation are beta radiation and alpha radiation. Beta radiation consists of rapidly moving electrons, and alpha radiation consists of rapidly moving particles that are composed of two protons and two neutrons. Atoms of the same element that differ from one another in the number of neutrons present are called isotopes. Some isotopes of atoms, such as Cobalt 60, are natural sources of gamma radiation. X-ray machines and nuclear power reactors are also sources of gamma radiation. Radiation is of concern because, depending on its type, total amount, or rate of delivery, radiation can cause changes in the genetic material (DNA) within cells, or change the activities of cells. In very high doses, it kills cells directly. Radiation dosage is measured in rads. A rad (radiation absorbed dose) is equal to 100 ergs of energy absorbed by 1 gram of material. Most human radiation doses are measured in milliards (mrad = 1/1,000 of a rad). Another unit that is often used to quantify radiation dosages is the rem (roentgen equivalent man). It is a slightly different way of measuring radiation, but for gamma radiation the rad and rem are equivalent. The following chart gives some idea of the amounts of radiation humans are likely to encounter. Kind of exposure | Dose(amount of exposure) | Effects of exposure(at dose shown) | Color television set | 0.5 mrad/yr | None known | Upper limit allowable from a nuclear power facility | 5 mrad/yr | None known | Chest X-ray | 5.8 mrad/X-ray | None known | Brain scan X-ray | 100
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