Problem: I read this background article the other day: One result of air pollution is acid rain. Acid rain is precipitation with a low (acidic) pH. This rain can be very destructive to wildlife. When acid rain falls in forests, freshwater habitats, or soils, it can kill insects and aquatic life. It causes this damage because of its very low pH. Sulfur oxides and nitrogen oxides in the air both cause acid rain to form ( Figure below ). Sulfur oxides are chemicals that are released from coal-fired power plants. Nitrogen oxides are released from motor vehicle exhaust.  I am facing a new situation today: Hydrologists studied two samples of rain water. Jim studied an acid rain sample from a nearby city, and Dan studied a sample of water from another town.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which hydrologist learned more about the causes of acid rain formation?

A: Jim


Problem: I read this background article the other day: Hydrogen bonds cause water to have a relatively high boiling point of 100°C (212°F). Because of its high boiling point, most water on Earth is in a liquid state rather than in a gaseous state. Water in its liquid state is needed by all living things. Hydrogen bonds also cause water to expand when it freezes. This, in turn, causes ice to have a lower density (mass/volume) than liquid water. The lower density of ice means that it floats on water. For example, in cold climates, ice floats on top of the water in lakes. This allows lake animals such as fish to survive the winter by staying in the water under the ice.  I am facing a new situation today: Bill was studying the states of matter. First, he selected a matter with low boiling point. He labeled it as matter A. To compare it with a well-known matter he selected water. He labeled it as matter B. He also selected ice, which he labeled as matter C. He is now better prepared to compare their states.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which matter is less needed by living things, matter B or matter C?

A: matter C


Problem: I read this background article the other day: Plants called epiphytes grow on other plants. They obtain moisture from the air and make food by photosynthesis. Most epiphytes are ferns or orchids that live in tropical or temperate rainforests (see Figure below ). Host trees provide support, allowing epiphyte plants to obtain air and sunlight high above the forest floor. Being elevated above the ground lets epiphytes get out of the shadows on the forest floor so they can get enough sunlight for photosynthesis. Being elevated may also reduce the risk of being eaten by herbivores and increase the chance of pollination by wind.  I am facing a new situation today: While hiking Bob likes to collect plant specimens. Yesterday, he was hiking along a creek, and was specifically looking for epiphytes. Eventually, he found one, and tagged the specimen as specimen A. To compare specimen A with another plant he collected another plant specimen that was not an epiphyte. He tagged that specimen as specimen B.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which specimen would most probably grow on the ground, specimen A or specimen B?

A: specimen B


Problem: I read this background article the other day: A period of very low rainfall occurred while the Grants were on the islands. The drought resulted in fewer seeds for the finches to eat. Birds with smaller beaks could eat only the smaller seeds. Birds with bigger beaks were better off. They could eat seeds of all sizes. Therefore, there was more food available to them. Many of the small-beaked birds died in the drought. More of the big-beaked birds survived and reproduced. Within just a couple of years, the average beak size in the finches increased. This was clearly evolution by natural selection.  I am facing a new situation today: Two bird islands in the Atlantic Ocean had very different climate changes during the last 5 years. Bone island experienced drought, while Finch island experienced flooding.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which island didn't display clear evidence of natural selection?

A:
Finch