Problem: 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. Given the paragraph above, please answer correctly the following question: Which hydrologist didn't learn that acid rain falls in freshwater habitats? Hint: 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.

A: Dan

Problem: Scientists are finding more and more evidences of water in the outer space. Earth has mostly liquid water. But that's not the case with other celestial objects. Venus has some water, but it is in gaseous state. On the other hand, water in Jupiter's moon Europa is in frozen state. Given the paragraph above, please answer correctly the following question: In Europa would the state of water in higher or lower denstiy than in Earth? Hint: Hydrogen bonds cause water to have a relatively high boiling point of 100C (212F). 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.

A: lower

Problem: Rob is experimenting with how air pressure works. To that end, he has designed two tests. In the first test the air flow works as it would in an airplane wing. He labels it as case A. In the second test the air flow works as it would in a race car spoiler. He labels it as case B. He is surprised to see that air flow behaves differently in different situations. Given the paragraph above, please answer correctly the following question: Would case A have higher or lower air pressure above it than case B? Hint: Bernoulli's law explains how the wings of both airplanes and birds create lift that allows flight (see Figure below ). The shape of the wings causes air to flow more quickly and air pressure to be lower above the wings than below them. This allows the wings to lift the plane or bird above the ground against the pull of gravity. A spoiler on a race car, like the one in Figure below , works in the opposite way. Its shape causes air to flow more slowly and air pressure to be greater above the spoiler than below it. As a result, air pressure pushes the car downward, giving its wheels better traction on the track.

A: lower

Problem: Mike is a biochemist, working for a science lab. Today, he has two organisms to investigate, organism A and organism B. He notices that organism A has enzymes, but organism B lacks enzymes. He needs to figure out how these conditions would affect the organisms. Given the paragraph above, please answer correctly the following question: Under normal conditions, in which organism the chemical reactions would be less plausible, organism A or organism B? Hint: Most chemical reactions within organisms would be impossible under the normal conditions within cell. For example, the body temperature of most organisms is too low for reactions to occur quickly enough to carry out life processes. Reactants may also be present in such low concentrations that it is unlikely they will meet and collide. Therefore, the rate of most biochemical reactions must be increased by a catalyst. A catalyst is a chemical that speeds up chemical reactions. In organisms, catalysts are called enzymes .

A:
organism B