Problem: I read this background article the other day: A mycorrhiza (Greek for "fungus roots") is a symbiotic association between a fungus and the roots of a plant. In a mycorrhizal association, the fungus may colonize the roots of a host plant by either growing directly into the root cells, or by growing around the root cells. This association provides the fungus with relatively constant and direct access to glucose, which the plant produces by photosynthesis. The mycelia of the fungi increase the surface area of the plant's root system. The larger surface area improves water and mineral nutrient absorption from the soil. I am facing a new situation today: Students working on their thesis for graduate school decide that they will write about the differences between two identical plants, but they will infect one of the plants with a fungus. This fungus will create a mycorrhizal association between one of the plants and the fungus. After caring for the plants, the students have grown fond of them and given them names. They have named one of them Audrey and the other Baudrey. They flip a coin to decide which plant will be infected with the fungus, and fate has decided that Audrey will have the fungus grow on it. Baudrey will be left to grow naturally. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Will Baudrey absorb minerals better or worse than Audrey?

A: worse

Problem: I read this background article the other day: Any unused energy in food, whether it comes from carbohydrates, proteins, or lipids, is stored in the body as fat. An extra 3,500 Calories of energy results in the storage of almost half a kilogram (1 pound) of stored body fat. People who consistently consume more food energy then they need may become obese. Obesity occurs when the body mass index is 30.0 kg/m 2 or greater. Body mass index (BMI) is an estimate of the fat content of the body. It is calculated by dividing a person's weight (in kilograms) by the square of the person's height (in meters). Obesity increases the risk of health problems such as type 2 diabetes and hypertension. I am facing a new situation today: Two men go into the doctor's office for a checkup. Stepping on the scale, the doctor weighs each of them. Tom has an average and healthy weight. However, Joe has a weight that indicates he is obese. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Who has a higher BMI?

A: Joe

Problem: I read this background article the other day: Pressures are given in a multitude of units. We've already discussed Pascals, and we know that another unit for pressure is the atmosphere (1 atm = 101.3 x 10 5 Pa). The third commonly used pressure unit is the torr (symbol Torr). 760 torr is 1 atm, but 1 torr is also the increase in pressure necessary to cause liquid mercury to rise by 1 mm. For that reason, torr is also commonly referred to as "millimeters mercury." Another pressure unit commonly used in our everyday world is psi, or pounds per square inch, though neither psi nor torr are SI units. I am facing a new situation today: Mike is studying for his physics exam. He realizes that the best way to learn physics is to solve problems. To that end, he needs to to convert pressure of objects from one unit to another. In one problem, four scenarios are given for the same object, scenario A, scenario B, scenario C, and scenario D. In scenario A the pressure is given in Pascals. In scenario B the pressure is given in the atm. In scenario C the pressure is given in torr. Lastly, in scenario D the pressure is given in psi. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: In which scenario SI unit is used, scenario C or scenario D?

A: scenario C

Problem: I read this background article the other day: Predators play an important role in an ecosystem. For example, if they did not exist, then a single species could become dominant over others. Grazers on a grassland keep grass from growing out of control. Predators can be keystone species . These are species that can have a large effect on the balance of organisms in an ecosystem. For example, if all of the wolves are removed from a population, then the population of deer or rabbits may increase. If there are too many deer, then they may decrease the amount of plants or grasses in the ecosystem. Decreased levels of producers may then have a detrimental effect on the whole ecosystem. In this example, the wolves would be a keystone species. I am facing a new situation today: Mike is studying the predator prey relationship. He is specifically studying three species, species A, species B, and species C. Species A is a predator; species B is the prey; and species C is a plant species that species B lives on. Mike now needs to figure out how the predator prey relationship balance the ecosystem. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: If species A population decrease, would it affect the ecosystem positively or negatively?

A:
negatively