... to day length is linked to an inner, light-sensitive circadian rhythm. In the temperate zones, day lengths during the natural 24-hour cycle vary with the seasons. In winter and spring, the period of light lengthens; in summer and autumn, it shortens. Plants in these zones undergo alternate 12-hour phases of light sensitivity. During one 12-hour phase, decreasing exposure to light induces a short-day reaction. For example, deciduous trees under the influence of the shorter days of fall drop their leaves. During the other 12-hour phase, more exposure to light creates a long-day reaction. Deciduous trees grow ...

... water and use siphon tubes to breath while floating near the water surface. After feeding on micro-organisms and growing larger, they shed their skin four times and evolve into the pupa stage. The pupa stage of development is a time when the young mosquito does not feed. After about two days the pupa evolves into an adult mosquito. The new adult mosquito escapes from the pupae skin be splitting the skin open and resting at the water surface to allow its' body parts to harden. can complete the entire egg to adult cycle in 10 to 14 days, depending on the temperature, with shorter times during warmer periods. Some ...

... 1998 was described by meteorologists at the US National Center in Miami, as the most intense western-hemisphere tropical cyclone on record. Large areas of Jamaica were devastated and the country’s Prime Minister, Edward Seaga, pronounce it the worst natural disaster ever to strike his country. Greatest loss of life however, occurred in Mexico where Gilbert hit twice, first of all traversing the Yucatan Peninsula and two days later making landfall some 150 km south of the border with the USA, finally dissipating near the city of Monterrey. During its most intense phase at the western end of the Caribbean Sea, ...

... The cathode electrode is reversible between Ni(OH)2 and nickel oxyhydroxide (NiOOH). At both electrode, oxidation-reduction reactions take place in an alkaline medium consisting of 30% by weight KOH in water. When charging, Ni(OH)2 at the positive electrode becomes oxidized and the metal hydride becomes reduced. In fact, the hydrogen which was separated from water come to react with the metal in the negative electrode to form MH. On the other hand, the hydroxyl ion ( from water) reacts with Ni(OH)2 at the positive electrode to form NiOOH. Ni now change from +2 to +3. Ni(OH)2 +OH = NiOOH + H2O + e From equation ...

... engineering falls into this category. A second example is biowarfare. Perhaps some of you saw the recent New Yorker article on the subject [Richard Preston, "Annals of Warfare: the Bioweaponeers." New Yorker, March, 1998]. There is widespread consensus that the information reported in that article is true. One of the things he mentions is that the former Soviet Union had the largest big-warfare program in the world, with 32,000 scientists working on it. Much of it had to do with genetic engineering. In one of the projects they took smallpox, which has otherwise disappeared from the world, and found a ...

... these single strands of a DNA molecule, a mRNA molecule is built. This is accomplished by an enzyme which travels along a portion of DNA between two exons and attaches the opposing base pairs to the backbone of the mRNA (a structure composed of phosphates and ribose). The nitrogen bases of this new molecule are identical to that of the opposite side of the original DNA molecule except that the thymine has been replaced with uracil. The formation of this molecule allows for the construction of proteins in the ribosome without risking the DNA in the cytoplasm. The mRNA travels through the cell to a ribosome. Here tRNA ...

... known as the “theory of evolution.” There are three main theories of evolution, which are, the early theories proposed by Comte de Buffon, Baron Cuvier, and Lamarck, the synthetic theory, and the Darwin theory. In the 1700s, French naturalists, Comte de Buffon and Baron Cuvier concluded with the studies of fossils and comparative anatomy that life on earth had endured many changes through a long period of time. In the early 1800s, another French naturalist named Lamark, proposed the first complete theory of evolution. He observed through is observations, depending on the extent to which the use of the ...

... dates back much further. As early as the sixteenth century it was recognized that men who worked in pitchblende( a chemical containing iron ore) mines were subject to fatal pulmonary diseases. An early study of the Schneeberg mines of Germany conducted between 1869 and 1877 found that 650 miners working in the mines had a life expectancy of 20 years after entering the mines. It was two german doctors, Harting and Hesse, who brought this to the public. The doctors found that 75 percent of the miner deaths were due to lung cancer. But with their scientific knowledge the doctors could only assume that the deaths were c ...

... SCIENTIFIC CLASSIFICATION: Kingdom: Animalia Phylum: Arthropoda Sub-phylum: Chelicerata Class: Insecta Order: Thysanum Family: Lepismati Genus: Metalus Species: Gerrainus LIFE CYCLE: Silverfish undergo incomplete metamorphosis. Adults lay eggs in small groups containing a few to 50 eggs. The eggs are very small and deposited in cracks and crevices. A female normally lays less than 100 eggs during her life span . Under ideal conditions, the eggs hatch in two weeks, but may take up to two months to hatch. The young nymphs are very much like the adults except for size. Several years are require ...

... of the greenhouse effect will be that the world's oceans will rise a possible 1 to 4 feet. Temperatures are expected to rise causing more rain in some places and less in others. Another provider to the greenhouse effect is the use of CFCs. CFCs, or chlorofluorocarbon, are used in making plastics and in aerosol spray cans, refrigerants, air conditioners, and similar objects. Like carbon dioxide, the CFCs are trapping more heat in the earth's atmosphere. CFCs have also been blamed for ozone depletion. CFCs are suspected of breaking down ozone particles that shield us from the sun's ultraviolet rays. Too many ultr ...