(a)   . When oxygen comes in contact with most metals, they rust. Aluminum is a special metal that does not rust. Instead, it reacts with oxygen in a different way. It forms a tough surface film that stops rust. Things that need to spend a lot of time outside are often made of aluminum. This is why people use aluminum to make cars and airplanes. It can also be used as a building material. However, aluminum doesn’t have the strength of steel. When strength is needed, even rusty steel is stronger than aluminum.

(a)   . Scientists have discovered a spider which is remarkably different from any other known spider. This spider, named Micromegale debliemma, has only two eyes where most spiders have six or eight. Unlike most spiders, it does not have lungs but instead absorbs oxygen through its skin. Just three one-hundredth of an inch long, Micromygale is one of the world’s smallest spiders.

(a)   . The Black Plague killed about one-third of Europe's whole population from 1347-1351. The Black Plague was caused because back then people knew almost nothing about germs or sanitary conditions. They had no idea how the disease spread. Rats ran everywhere. Fleas lived on the rats. These fleas carried the deadly Black Plague germ. Just before the Plague broke out, people had killed off a great many cats. Up until then the cats had kept the rat population small. With fewer cats, there were more rats than ever before. And every rat had the plague-infested fleas in its fur.

(a)   . A focus group is a small group, usually consisting of about seven to ten people who are brought together to discuss a subject of interest to the researcher. Focus groups are commonly used today in business and politics; that flashy slogan you heard for a political campaign or a
new toothpaste was almost certainly tested in a focus group to gauge people’s reactions. Social researchers may use a focus group to help design questions or instruments for quantitative research or to study the interactions among group members on a particular subject. In most
cases, researchers ask predetermined questions, but the discussion is unstructured. Focus groups are a relatively cheap method of research and can be completed quickly. They also allow for the flexible discussions and answers that are desirable in qualitative research
—Kunz, THINK Marriages & Families, p.36

(a)   . In the developing world 1.1 billion people still lack access to safe drinking water, 2.6 billion do not have access to adequate sanitation services, and more than 1.6 million deaths each year are traced to waterborne diseases (mostly in children under five). All too often in developing countries, water is costly or inaccessible to the poorest in society, while the wealthy have it piped into their homes. In addition, because of the infrastructure that is used to control water, whole seas are being lost, rivers are running dry, millions of people have been displaced to make room for reservoirs, groundwater aquifers are being pumped down, and disputes over water have raised tensions from

local to international levels. Fresh water is a limiting resource in many parts of the world and is certain to become even more so as the 21st century unfolds.

—Wright and Boorse, Environmental Science, p. 247

(a)   . In colonial days, huge flocks of snowy egrets inhabited the coastal wetlands and marshes of the southeastern United States. In the 1800s, when fashion dictated fancy hats adorned with feathers, egrets and other

birds were hunted for their plumage. By the late 1800s, egrets were almost extinct. In 1886, the newly formed National Audubon Society began a press campaign to shame “feather wearers” and end the practice. The campaign caught on, and gradually, attitudes changed; new laws followed. Government policies that protect animals from overharvesting are essential to keep species from the brink of extinction. Even when cultural standards change due to the efforts of individual groups (such as the National

Audubon Society), laws and policy measures must follow to ensure that endangered populations remain protected. Since the 1800s, several important laws have been passed to protect a wide variety of species.

—Wright and Boorse, Environmental Science:

Toward a Sustainable Future, p. 150

(a)   . The National Cancer Institute (NCI) has taken a brute-force approach to screening species for cancer-suppressing chemicals. NCI scientists receive frozen samples of organisms from around the world, chop them up, and separate them into a number of extracts, each probably containing hundreds of components. These extracts are tested against up to 60 different types of cancer cells for their efficacy in stopping or slowing growth of the cancer. Promising extracts are then further analyzed to determine their chemical nature, and chemicals in the extract are tested singly to find the effective compound. This approach is often referred to as the “grind ’em and find ’em” strategy.

(a)   . The United States has a severe fire problem that if not addressed, will continue to worsen drastically. Fire statistics show that our nation, one of the richest and

most technologically sophisticated countries in the world, lags behind its peer nations in fire security. Nationally, there are millions of fires, thousands of deaths, tens of thousands of injuries, and billions of dollars lost each year—figures which far exceed comparable statistics for other industrialized countries. In 2001, for example, the direct value of property destroyed in fires was $11 billion ($44 billion if the World Trade Center loss is included). More recently in 2004, direct property losses from fires were estimated at over $9.8 billion.

—Loyd and Richardson, Fundamentals of Fire and Emergency Services, p. 12

(a)   . For decades, we have looked at our steadily increasing life expectancy rates and proudly proclaimed that Americans’ health has never been better. Recently,

however, health organizations and international groups have attempted to quantify the number of years a person lives with a disability or illness, compared with the number of healthy years. The World Health Organization summarizes this concept as healthy life expectancy. Simply stated, healthy life expectancy refers to the number of years a newborn can expect to live in full health, based on current rates of illness and mortality and also on the quality of their lives. For example, if we could delay the onset of diabetes so that a person didn’t develop the disease until he or she was 60 years old, rather than developing it at 30, there would be a dramatic increase in this individual’s healthy life expectancy.

—Donatelle, Health: The Basics, p. 6