user: Problem: Given the question: I read this background article the other day: Excess intake of calcium may cause hypercalcaemia. However, because calcium is absorbed rather inefficiently by the intestines, high serum calcium is more likely caused by excessive secretion of parathyroid hormone (PTH) or possibly by excessive intake of vitamin D, both which facilitate calcium absorption. It may also be due to bone destruction that occurs when tumours metastasize within bone. All these conditions result in excess calcium salts being deposited in the heart, blood vessels, or kidneys. Symptoms include anorexia, nausea, vomiting, memory loss, confusion, muscle weakness, increased urination, dehydration, and metabolic bone disease. Chronic hypercalcaemia typically leads to calcification of soft tissue and its serious consequences: for example, calcification can cause loss of elasticity of vascular walls and disruption of laminar blood flow—and thence to plaque rupture and thrombosis. Conversely, inadequate calcium or vitamin D intakes may result in hypocalcaemia, often caused also by inadequate secretion of parathyroid hormone or defective PTH receptors in cells. Symptoms include neuromuscular excitability, which potentially causes tetany and disruption of conductivity in cardiac tissue.  I am facing a new situation today: Two sisters went in for a medical examination. Mary had normal blood calcium level, but her sister Ann sadly found out that she has a condition named hypercalcaemia. Ann started a new treatment right away.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which sister didn't have excess calcium salts being deposited in the kidneys?
++++++++++++++++++++++++++++++++
The answer is:
Mary


Problem: Given the question: I read this background article the other day: Some individuals have a specific mutation in the primary sequence of their hemoglobin molecules that causes them to aggregate, resulting in a deformation of their red blood cells. This abnormality is genetic in nature. A person may inherit the gene from one parent and have sickle cell trait (only some of the hemoglobin is hemoglobin S), which is usually not life-threatening. Inheriting the gene from both parents will result in sickle cell disease, which is a very serious condition.  I am facing a new situation today: Dan studied two groups of individuals. Group S that had sickle cell anemia, and group B which had normal hemoglobin. He was fascinated by the results.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which group didn't have aggregating hemoglobin?
++++++++++++++++++++++++++++++++
The answer is:
group B


Problem: Given the question: 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: Karen studied animals in school. She started studying predators for a school presentation. She liked it. Her friend Molly liked cows, sheep and other herbivores, so she decided to do a presentation about grazers, and their role in nature.  Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which girl learned more about animals that keep grass from growing out of control?
++++++++++++++++++++++++++++++++
The answer is:


assistant: Molly