Problem: I have a new situation: United States has varied geographical characteristics. Take for example, the Mississippi Delta. The delta has vast wetland that gets inundated every year. On the contrary, farther west, the Mojave Desert in Nevada sees very little precipitation or floodwater. Both places are beautiful in their own right, and attract many tourists every year. But I can use this background: When soil is flooded, hypoxia develops, as soil microorganisms consume oxygen faster than diffusion occurs. The presence of hypoxic soils is one of the defining characteristics of wetlands. Many wetland plants possess aerenchyma, and in some, such as water-lilies, there is mass flow of atmospheric air through leaves and rhizomes. There are many other chemical consequences of hypoxia. For example, nitrification is inhibited as low oxygen occurs and toxic compounds are formed, as anaerobic bacteria use nitrate, manganese, and sulfate as alternative electron acceptors. The reduction-oxidation potential of the rhizhosphere decreases and metal ions such as iron and manganese precipitate. Aerenchyma is a modification of the parenchyma. What is an answer for this question: In which place less metal ions would precipitate, Mississippi Delta or Mojave Desert?

A: Mojave Desert

Problem: I have a new situation: Michael and Robert are two patients at a cardiology clinic. Both just received their blood test results and were told that they need to improve their cholesterol levels. They were each recommended to make changes to their diets. Michael took this advice to heart, and reduced the levels of saturated fat and dietary cholesterol he consumed. Robert, on the other hand, continued to consume high levels of saturated fat and dietary cholesterol. But I can use this background: Cholesterol can't dissolve in the blood. It has to be transported to and from the cells by carriers called lipoproteins. Low-density lipoprotein, or LDL, is known as "bad" cholesterol. High-density lipoprotein (HDL) is known as good cholesterol. When too much LDL cholesterol circulates in the blood, it can slowly build up in the inner walls of the arteries that feed the heart and brain. Together with other substances, it can form plaque, and lead to atherosclerosis. If a clot forms and blocks a narrowed artery, a heart attack or stroke can result. Cholesterol comes from the food you eat as well as being made by the body. To lower bad cholesterol, a diet low in saturated fat and dietary cholesterol should be followed. Regular aerobic exercise also lowers LDL cholesterol and increases HDL cholesterol. What is an answer for this question: Who will be at greater risk for atherosclerosis in the future?

A: Robert

Problem: I have a new situation: Benjamin is taking an Army training class and is learning to operate a tank. Today, he is in a tank with an instructor on a training course. Benjamin drives the tank forward and comes to a large dirt mound blocking his path. He needs to decide whether to break the left tread or right tread. But I can use this background: The refraction of waves across boundaries operates similarly to the method by which tanks are steered. Tanks do not have a steering wheel. Instead, they have an accelerator to produce forward motion and separate brakes on each tread. The operator uses brakes on both treads at the same time in order to stop, but brakes on only one tread to turn the tank. By braking one side, the operator causes that side to slow down or stop while the other side continues at the previous speed, causing the tank to turn towards the slower tread. What is an answer for this question: If Benjamin breaks the left tread which direction will the tank turn?

A: left

Problem: I have a new situation: Hill town had two large forests nearby. Lake forest had trees that were in a symbiotic relationship with a large variety of arbuscular mycorrhizal fungi. These fungi were less prevalent in Brook forest. But I can use this background: Arbuscular mycorrhizal fungi vary across many environmental gradients. Their tolerance to freezing and drying is known to shift between AM fungal taxa. AM fungi become less prevalent and diverse at higher soil nutrient and moisture concentrations, presumably because both plants allocate less carbon to AM fungi and AM fungi reallocate their resources to intraradical hyphae in these environmental conditions. Over the long term, these environmental conditions can even create local adaptation between plant hosts, AM fungi and the local soil nutrient concentrations. What is an answer for this question: Which forest had fewer AM fungi which reallocate their resources to intraradical hyphae?

A:
Lake