1.

There are three classes of mammals: monotremes, marsupials, and placentals.The monotreme class includes the primitive egg-laying mammals that live in Australia and New Guinea. Only the platypus and the echidna (a burrowing, insect-eating mammal that is also known as the spiny anteater) are members of this class. The marsupial class includes animals whose offspring develop inside a pouch on the mother's belly. Kangaroos and koalas are examples of marsupials. The largest of the three groups are the placental mammals. Placental young develop inside their mother's body while attached to a placenta. This is an organ that provides nourishment from the mother's blood. Horses, cats, monkeys, and human beings are all examples of placental mammals. (Source of information: Ronda Messick Bungardner, "Straight Answers," The News Herald (Morganton, NC), June 27, 2004, p. 2C.)

2.

Before the U.S. Food and Drug Administration will approve a new drug, it must determine that the drug is both safe and effective.Therefore, every potential new treatment is tested on human volunteers in clinical trials that last, on average, for seven years.In the first phase of a clinical trial, twenty to eighty volunteers, some of whom may be healthy, test the drug to identify how it works.In the second phase, the drug is tested on anywhere from one hundred to three hundred people who suffer from the disease the drug is supposed to treat. During these clinical trials, researchers try to determine the drug's risks and side effects. If the second phase indicates that the drug will be effective, the third phase tests 1,000 to 3,000 people with the disease. The fourth and final phase occurs after the drug is actually on the market and available to the public.At this point, ongoing trials monitor the drug's long-term effects. They also study how different groups, such as the elderly, react to the drug. (Source of information: "Clinical Trials Take Years," no author credited, USA Today, August 10, 2004, p. 10A; National Institutes of Health, "Glossary of Critical Trials Terms," ClinicalTrials.gov, http://www.clinicaltrials.gov/ct/gui/info/glossary)

3.

The two types of rainforests in the world are tropical rainforests and temperate rainforests.Tropical rainforests are found close to the equator in 85 different countries, where temperatures stay above 80 degrees all year round. Temperate rainforests are found near coastal areas that are farther north or south of the equator, such as New Zealand, Chile, Scotland, and the Pacific coast of Canada and the United States. Both types of rainforest are very lush and wet. Both contain vegetation that is tall, dense, and extremely green.Each is also rich in plant and animal life.Tropical rainforests, however, are much warmer than temperate rainforests. They are also much older.Tropical rainforests are millions of years old. Temperate rainforests are less than 10,000 years old. Tropical rainforests also get more rain. While temperate rainforests get about 100 inches of rain per year, tropical rainforests get about 400 inches per year. The variety of life forms is also greater in the tropical rainforest. This may be the reason why tropical rainforests are home to at least half-and maybe as much as 90 percent-of Earth's plant and animal species. (Source of information: Missouri Botanical Garden, "Types of Rainforests," 2002, mbgnet.mobot.org/sets/rforest/types.htm)

4.

A dysphemism is a word or phrase used to be intentionally offensive, or cruel. These terms make whatever they refer to sound worse. Put-downs such as "nerd" and "my old man" are examples of dysphemisms. Many terms that belittle or degrade one's race, gender, nationality, or religion are also dysphemisms. Examples include "frog" ("French person"), "chick" ("woman") and Bible-thumper ("Christian"). Many profanities are dysphemisms.Taboo words that refer to the genitals, sexual acts, and bodily functions (such as crapper for "toilet") are also dysphemisms. Crude phrases referring to death, such as "kicked the bucket" or "worm food," are dysphemisms as well.Dysphemisms are usually used for the purpose of provoking a humorous response or getting a negative reaction from listeners, viewers, or readers.

5.

In the 1930s, a combination of drought and soil erosion caused the "Dust Bowl" to form in parts of Oklahoma, Arkansas, and Texas. In 1931, a severe drought hit the Great Plains of the United States. Due to the lack of water, crops began to die. Dust from the over-plowed land began to blow, causing dust storms. Over the next several years, as the drought continued, the number of dust storms increased. In 1932, there were 18 major storms, and in 1933, there were 38.By 1934, the Great Plains had become a desert, but the worst was yet to come. On April 14, 1935, a day now known as Black Sunday, a huge black cloud of dust blocked out the sun and engulfed people, livestock herds, and homes in so much dirt that it was piled up in drifts, like snow. The dust was so bad, people were forced to tie handkerchiefs over their faces and put vaseline in their nostrils to keep out the dust. Following Black Sunday, the federal government finally began creating programs in an attempt to reverse the damage. These programs encouraged farmers to change agricultural practices that had thrown the natural environment out of balance. By this time, though, many people had lost their land in bank foreclosures and were abandoning the area to live elsewhere. By 1940, 2.5 million people had moved away from the Plains states.In all, one-fourth of the population pulled up stakes to go look for greener pastures. (Source of information: "Surviving the Dust Bowl," PBS, www.pbs.org/wgbh/amex/dustbowl)