I read this background article the other day: Another major cause of extinction is global warming , which is also known as global climate change. During the past century, the Earth's average temperature has risen by almost 1C (about 1.3F). You may not think that is significant, but to organisms that live in the wild and are constantly adapting to their environments, any climate change can be hazardous. Recall that burning fossil fuels releases gasses into the atmosphere that warm the Earth. Our increased use of fossil fuels, such as coal and oil, is changing the Earth's climate. Any long-term change in the climate can destroy the habitat of a species. Even a brief change in climate may be too stressful for an organism to survive. For example, if the seas increase in temperature, even briefly, it may be too warm for certain types of fish to reproduce. I am facing a new situation today: Ken and Stacy are two engineers discussing their plans about what source of energy they should use to generate electricity in a new city they are helping design. Ken feels that they should use coal since it's reliable, abundant and relatively cheap. Stacy argues that they should use solar power because there is an infinite supply of solar energy. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Will Stacy's plan increase the temperature of the oceans more or less than Ken's
Ans: less

I read this background article the other day: Rain dissolves fertilizer in the soil. Runoff carries it away. The fertilizer ends up in bodies of water, from ponds to oceans. Nitrogen is a fertilizer in the water. Since there is a lot of nitrogen, it causes algae to grow out of control. Pictured below is a pond covered with algae ( Figure below ). Algae use up carbon dioxide in the water. After the algae die, decomposers break down the dead tissue. The decomposers use up all the oxygen in the water. This creates a dead zone. A dead zone is an area in a body of water where nothing grows because there is too little oxygen. There is a large dead zone in the Gulf of Mexico ( Figure below ). The U.S. states outlined on the map have rivers that drain into the Gulf of Mexico. The rivers drain vast agricultural lands. The water carries fertilizer from these areas into the Gulf. I am facing a new situation today: Park farm and Fiddle farm provided Red city with tonnes of produce annually. Fiddle farm used and abundance of fertilizers and pesticides, while Park farm didn't use any of those substances. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which farm caused less fertilizer to dissolve in the soil because of rain?
Ans: Park

I read this background article the other day: Many different chemical substances cause cancer. Dozens of chemicals in tobacco smoke, including nicotine, have been shown to cause cancer ( Figure below ). In fact, tobacco smoke is one of the main sources of chemical carcinogens. Smoking tobacco increases the risk of cancer of the lung, mouth, throat, and bladder. Using smokeless tobacco can also cause cancer. Other chemicals that cause cancer include asbestos, formaldehyde, benzene, cadmium, and nickel. I am facing a new situation today: Walter and Jesse, two coworkers, are sitting at a hotel bar having a drink together after a long day at a conference when they start discussing their smoking habits. Walter shares that he has regularly smoked a pack of cigarettes for the past ten years. Jesse says he only smoked a couple cigarettes during college while he was drinking and isn't a regular smoker. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which man is more likely to have lung cancer?
Ans: Walter

I read this background article the other day: HIV , or human immunodeficiency virus, causes AIDS. AIDS stands for "acquired immune deficiency syndrome." It is a condition that causes death and does not have a known cure. AIDS usually develops 10 to 15 years after a person is first infected with HIV. The development of AIDS can be delayed with proper medicines. The delay can be well over 20 years with the right medicines. Today, individuals who acquire HIV after 50 years of age can expect to reach an average human life span. I am facing a new situation today: Two college buddies have known each other for 20 years. Tim was HIV positive while John was not and he didn't have a problem with it. Both friends are 40 years old. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which friend cannot expect to reach an average human life span?
Ans: Tim