Problem: I read this background article the other day: When you add sugar to a cold drink, you may stir it to help the sugar dissolve. If you don't stir, the sugar may eventually dissolve, but it will take much longer. Stirring is one of several factors that affect how fast a solute dissolves in a solvent. Temperature is another factor. A solid solute dissolves faster at a higher temperature. For example, sugar dissolves faster in hot tea than in ice tea. A third factor that affects the rate of dissolving is the surface area of the solute. For example, if you put granulated sugar in a glass of ice tea, it will dissolve more quickly than the same amount of sugar in a cube. That's because granulated sugar has much more surface area than a cube of sugar. You can see videos of all three factors at these URLs I am facing a new situation today: Justin and Alejandro are conducting a chemical experiment involving sodium hydroxide. A key part of the reaction is ensuring that the sodium hydroxide is dissolved in water before adding the other materials. Justin adds the sodium hydroxide to reaction A, and begins stirring the mixture with a spoon. Alejandro also adds sodium hydroxide to his reaction, reaction B, but doesn't stir it because he is lazy. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Whose sodium hydroxide, Justin's or Alejandro's, will dissolve faster?

A: Justin's

Problem: I read this background article the other day: Most chemical reactions within organisms would be impossible under the conditions in cells. 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 . Essentially, enzymes are biological catalysts. I am facing a new situation today: Scientists have recently discovered two organisms deep in a cave in the hills of Paris. One organism, Boncho, has many enzymes. The other organism, Hojo, has very few enzymes. Currently, scientists are in the process of analyzing these new organisms to learn more about them. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which organism will have a harder time creating chemical reactions?

A: Hojo

Problem: I read this background article the other day: Once again, a mutation is the change in the DNA or RNA sequence. In multicellular organisms, mutations can be subdivided into germline mutations and somatic mutations. Germline mutations occur in the DNA of sex cells, or gametes, and are therefore potentially very serious. These mutations can be passed to the next generation. If the zygote contains the mutation, every cell in the resulting organism will have that mutation. If the mutation results in a disease phenotype, the mutation causes what is called a hereditary disease. Somatic mutations , which occur in somatic, or body, cells, cannot be passed to the next generation (offspring). Mutations present in a somatic cell of an organism will be present (by DNA replication and mitosis) in all descendants of that cell. If the mutation is present in a gene that is not used in that cell type, the mutation may have no effect. On the other hand, the mutation may lead to a serious medical condition such as cancer. I am facing a new situation today: The specialists studied two groups of larvae. Group L displayed all kinds of mutations while group D didn't. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which group of larvae had more germline mutations?

A: Group L

Problem: I read this background article the other day: Cholesterol has been implicated in heart disease for decades. Atherosclerosis is a disorder of the arteries in which cholesterol and other materials are deposited on the interior of the arterial wall. These deposits lead to the formation of plaques that can restrict or even block the flow of blood through these blood vessels (see Figure below ). A decrease in the flow of blood can lead to high blood pressure and a lowered oxygen supply to the heart muscle. A complete blockage of blood flow to parts of the heart (a heart attack) can cause significant damage due to oxygen deprivation, in some cases leading to death. I am facing a new situation today: Fred was a good athlete in his youth, and so was Vic. Fred started eating junk food and other fatty foods in his 30's. His cholesterol is very high now. Vic became a vegan later,and he is in a very good physical shape. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which friend had a decreased blood flow to the heart?

A:
Fred