[Q]: 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 flowand 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 brothers went to the doctor's office for a medical exam and blood tests. Dan found out he is healthy and had normal blood cholesterol and calcium levels. Ben however, was told that he had a disease called hypercalcaemia and had to start a treatment for that. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which brother had excess calcium salts deposited in the blood vessels?
****
[A]: Ben

[Q]: I read this background article the other day: Alpine tundra occurs at high enough altitude at any latitude. Portions of montane grasslands and shrublands ecoregions worldwide include alpine tundra. Large regions of alpine tundra occur in the North American Cordillera, the Alps and Pyrenees of Europe, the Himalaya and Karakoram of Asia, the Andes of South America, and the Eastern Rift mountains of Africa.Alpine tundra occupies high-mountain summits, slopes, and ridges above timberline. Aspect plays a role as well; the treeline often occurs at higher elevations on warmer equator-facing slopes. Because the alpine zone is present only on mountains, much of the landscape is rugged and broken, with rocky, snowcapped peaks, cliffs, and talus slopes, but also contains areas of gently rolling to almost flat topography.Averaging over many locations and local microclimates, the treeline rises 75 metres (245 ft) when moving 1 degree south from 70 to 50N, and 130 metres (430 ft) per degree from 50 to 30N. Between 30N and 20S, the treeline is roughly constant, between 3,500 and 4,000 metres (11,500 and 13,100 ft). I am facing a new situation today: Pam and Alice studied Earth's climate and vegetation. Pam studied more about high latitudes (70 to 50N), while Alice studied about lower latitudes (30N to 20S). Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which person studied less about portions of shrublands ecoregions ?
****
[A]: Alice

[Q]: I read this background article the other day: Rain dissolves fertilizer in the soil. Runoff carries it away. The fertilizer ends up in bodies of water, from ponds to oceans. Nitrogen is a fertilizer in the water. Since there is a lot of nitrogen, it causes algae to grow out of control. Pictured below is a pond covered with algae ( Figure below ). Algae use up carbon dioxide in the water. After the algae die, decomposers break down the dead tissue. The decomposers use up all the oxygen in the water. This creates a dead zone. A dead zone is an area in a body of water where nothing grows because there is too little oxygen. There is a large dead zone in the Gulf of Mexico ( Figure below ). The U.S. states outlined on the map have rivers that drain into the Gulf of Mexico. The rivers drain vast agricultural lands. The water carries fertilizer from these areas into the Gulf. I am facing a new situation today: Two farms were supplying produce to a large city. Green farm used organic methods and no fertilizers, while Bean farm used fertilizer to improve production. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which farm contributes more to the consumption of oxygen in the water?
****
[A]: Bean

[Q]: I read this background article the other day: Clouds on Earth are made of water vapor. Venus's clouds are a lot less pleasant. They are made of carbon dioxide, sulfur dioxide and large amounts of corrosive sulfuric acid! The atmosphere of Venus is so thick that the pressure on the surface of Venus is very high. In fact, it is 90 times greater than the pressure at Earth's surface! The thick atmosphere causes a strong greenhouse effect. As a result, Venus is the hottest planet. Even though it is farther from the Sun, Venus is much hotter even than Mercury. Temperatures at the surface reach 465C (860F). That's hot enough to melt lead! I am facing a new situation today: Two groups of children studied about some of the planets from our Solar system and their atmospheres. Group E studied about Earth, while group V studied about the planet Venus. Using the knowledge I acquired from the background article, how should I answer correctly the following question regarding my new situation: Which group studied less about clouds made of water vapor?
****
[A]:
group V