ANTIBIOTIC SUSCEPTIBILITY TESTING. Bacteria demonstrate two kinds of resistance to antibiotics, namely intrinsic resistance and acquired resistance. Intrinsic resistance means that the species was resistant to an antibiotic even before its introduction.
Radiation is naturally present in our environment, as it has been since before the birth of this planet. In addition, radiation can be produced artificially, as in medical x-rays and microwaves for cooking. Nonetheless, most people are not aware of all the natural and man-made sources of radiation in our environment.
Radiation occurs when energy is emitted by a source and then travels through a medium, such as air, until it is absorbed by matter. Radiation can be described as two basic types, ionizing and non-ionizing radiation. Non-ionizing radiation. Ionizing radiation. 1  Natural background radiation. 2  Cosmic radiation. 3  Terrestrial radiation. 4  Inhalation. 5  Ingestion. 6  Artificial sources of radiation.