Problem: Given the background: Protozoa generally feed by engulfing and digesting other organisms. As consumers, they have various roles in food chains and webs. Some are predators. They prey upon other single-celled organisms, such as bacteria. In fact, protozoa predators keep many bacterial populations in check. Other protozoa are herbivores. They graze on algae. Still others are decomposers. They consume dead organic matter. There are also parasitic protozoa that live in or on living hosts. For example, the protozoan that causes malaria lives inside a human host. For their part, protozoa are important food sources for many larger organisms, including insects and worms. and the situation: Reed started studying protozoa and was more interested in the predatorial behaviors of protozoa, while Brad wanted to know more about other types of protozoa, suck as grazers and decomposers. Answer the following question: Which person learned more about protozoa that graze on algae?

A: Brad

Problem: Given the background: During late adulthood, the risk of developing diseases such as cardiovascular diseases and cancer continues to rise. Most people also have a decline in strength and stamina. Their senses may start failing, and their reflex time typically increases. Their immune system also doesn't work as well as it used to. As a result, common diseases like the flu may become more serious and even lead to death. The majority of late adults develop arthritis, and as many as one in four develop Alzheimer's disease. and the situation: Mike is studying the population growth rate of countries around the world. He noticed that countries like Japan and Russia are having a demographic shift. They have a growing population of late adulthood. He recorded the late adulthood population as population A. On the other hand, many developing countries have growing population of younger people. He recorded younger population as population B. Answer the following question: Which population would be less at risk of cancer or Alzheimer's disease, population A or population B?

A: population B

Problem: Given the background: This is how ice wedging works. When liquid water changes into solid ice, it increases in volume. You see this when you fill an ice cube tray with water and put it in the freezer. The ice cubes go to a higher level in the tray than the water. You also may have seen this if you put a can of soda into the freezer so that it cools down quickly. If you leave the can in the freezer too long, the liquid expands so much that it bends or pops the can. (For the record, water is very unusual. Most substances get smaller when they change from a liquid to a solid.) and the situation: Jeremy is performing some chores around the kitchen when he decides to pour himself some water into a blue cup. However, this water isn't cold enough so he puts it into the freezer to cool it down. He then pours himself the exact same amount of water in a red cup, but gets a phone call and leaves that cup on the table without taking a sip. He comes back two hours later after the phone call to get his cups of water back. Answer the following question: Will the water in the red or blue cup have more volume?

A: blue

Problem: Given the background: Liquid water is a fluid. The hydrogen bonds in liquid water constantly break and reform as the water molecules tumble past one another. As water cools, its molecular motion slows and the molecules move gradually closer to one another. The density of any liquid increases as its temperature decreases. For most liquids, this continues as the liquid freezes and the solid state is denser than the liquid state. However, water behaves differently. It actually reaches its highest density at about 4C. and the situation: Steve and Chris sit down at a new cafe that just opened up in town after hearing rave reviews of it at work. They look at the menus trying to decide what to order when a waiter shows up and asks if they would like anything to drink. Steve says he would like a glass of water that has molecules far apart. Chris orders water with molecules closer together. The waiter looks at them with a rather confused look and asks them to please elaborate. Answer the following question: Whose cup of water is less dense?

A:
Steve