Why do some parasites kill the host they depend upon while others coexist with their host? Two prime factors determine parasitic virulence: the manner in which the parasite is transmitted, and the evolutionary history of the parasite and its host. Parasites which have colonized a new host species tend to be more virulent than par...
Transgenic Organism, plant, animal, or bacteria that has been genetically modified to contain a gene from a different species. The new gene is inherited by offspring in the same way as the organism's own genes. The transgenic condition is achieved by injecting the foreign gene into the fertilized egg or into embryonic cells. The injected gene b...
DESERT BIOME Any barren region that supports very little life may be called a desert. The cold expanses of Antarctica, extreme northern Asia, and Greenland are therefore true, but cold, deserts. Most commonly, however, the term desert is used for regions that are barren because they are arid, or dry. Arid deserts receive little precipitati...
Endangered species are living things whose population is so reduced that they are threatened with extinction. Thousands of species are included in this category. The International Union for the Conservation of nature and Natural Resources publishes a list of threatened mammals, birds, reptiles, amphibians, and (many people do not consider t...
Over the years, man has come up with countless inventions, each more resourceful than the last. However, as the computer age continues, mankind is threatened. Ridiculous, some may say, but I say look around! The computer has already begun to control so many of the vital functions that man has prided himself upon before. Our lives a...