user: I read this background article the other day: As a cell grows, its volume increases more quickly than its surface area. If a cell was to get very large, the small surface area would not allow enough nutrients to enter the cell quickly enough for the cell’s needs. This idea is explained in Figure below . However, large cells have a way of dealing with some size challenges. Big cells, such as some white blood cells, often grow more nuclei so that they can supply enough proteins and RNA for the cell’s requirements. Large, metabolically active cells often have lots of cell protrusions, resulting in many folds throughout the membrane. These folds increase the surface area available for transport of materials into or out of the cell. Such cell types are found lining your small intestine, where they absorb nutrients from your food through protrusions called microvilli .  I am facing a new situation today: Mike is studying for his biology exam. He found that all body cells are not equal in size - some are large and some are small. He labeled the large cells as class A cells. Then he labeled the small cells as class B cells. He is now prepared to find the differences between them.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Would class B cells have more or less folds on its membrane than class A cells?
Ans: less

I read this background article the other day: Besides anthropogenic productivity of the land, the biodiversity of degraded land also declines, as previously mentioned.[12] With less biodiversity, this ecosystem is less adaptable to when disasters strike it[11][8] It has a smaller available food supply, in terms of plants, for animals, who then may die out or more likely may relocate. Proof of this decline is that presently 15-20% of Tibetan Plateau species are now considered endangered; and now because of this animal and plant absence, the soil quality of these degraded lands is very poor.[1] It does not hold the necessary nutrients, such as water, nitrogen, and carbon, essential to either supporting life or inviting life back to that land.[6] As a result of such carbon and nitrogen loss in the Tibetan Plateau, $8,033/ha and $13,315/ha were respectively lost in economic terms. Soils are further weakened by dust storms whose frequency increases because of degradation.[11][4] Erosion of soil becomes a bigger problem, since no longer are there as many plants to anchor in the soil. In the northern Chinese province alone, 400 million are affected every year with an associated 54 billion yuan of annual economic loss due to grassland degradation.  I am facing a new situation today: Both Nicaragua and Costa Rica had large tract of pristine forests. They had one of the largest concentration of tropical species. In the 1980s Nicaragua started clearing up some of these forests. Instead, they have now vast tract of sugarcane production in that land. One can still visit Costa Rica where they kept those pristine forests intact.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: which country's ecosystem would most likely not adapt better if a disaster strikes, Nicaragua or Costa Rica?
Ans: Nicaragua

I read this background article the other day: Currently, millions of individuals with high cholesterol take a similar type of drug, known as a statin. The drug, an inhibitor of HMG-CoA reductase (3-hydroxy-3-methyl-glutaryl-CoA reductase), the rate limiting enzyme in cholesterol biosynthesis, decreases blood levels of cholesterol by induce the expression of low density lipoprotein (LDL) receptors in the liver. The increased levels of the LDL-receptors stimulate the catabolism of plasma LDL, removing cholesterol from plasma, which is an important determinant of atherosclerosis. You may know of people who take a statin to help with their cholesterol levels. However, these drugs probably work slightly differently in many of those people. In some, it lowers their cholesterol significantly; in others it may lower it only moderately; and in some, it may have no significant effect at all. (Luckily for those individuals, there are multiple versions of the statins, so different drugs can be tested to find the proper combination for that individual.) Why the difference? Because of the genetic background of all people; the different single nucleotide polymorphisms that make us all different. Pharmacogenomics, a combination of pharmacology and genomics (the study of the genome) that refers to the study of the relationship between pharmaceuticals and genetics, may explain and simplify this problem.  I am facing a new situation today: Two university students studied different types of drugs for their exams. Kate studied statins, while Carol studied anti-depressants.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which student learned less about an inhibitor of HMG-CoA reductase?
Ans: Carol

I read this background article the other day: The quantity of small plastic fragments floating in the north-east Pacific Ocean increased a hundredfold between 1972 and 2012.Marine pollution is a generic term for the harmful entry into the ocean of chemicals or particles. The main culprits are those using the rivers for disposing of their waste. The rivers then empty into the ocean, often also bringing chemicals used as fertilizers in agriculture. The excess of oxygen-depleting chemicals in the water leads to hypoxia and the creation of a dead zone.Marine debris, also known as marine litter, is human-created waste that has ended up floating in a lake, sea, ocean, or waterway. Oceanic debris tends to accumulate at the center of gyres and coastlines, frequently washing aground where it is known as beach litter.In addition, the Pacific Ocean has served as the crash site of satellites, including Mars 96, Fobos-Grunt, and Upper Atmosphere Research Satellite.  I am facing a new situation today: Tim and Joe were two friends living near two different oceans. Tim lived on the Pacific coast while Joe lived on the Atlantic coast.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which friend sees more marine litter?


assistant: Ans: Tim