[Q]: 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. 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. Which girl learned less about deer and rabbits?
****
[A]: Karen

input: Please answer the following: Often, foreign exchange controls can result in the creation of black markets to exchange the weaker currency for stronger currencies. This leads to a situation where the exchange rate for the foreign currency is much higher than the rate set by the government, and therefore creates a shadow currency exchange market. As such, it is unclear whether governments have the ability to enact effective exchange controls.[1] Booneland changed their foreign exchange controls and Bradland didn't. The foreign currency got more expensive and they had problems with a shadow currency exchange. Bradland people were more cautious and less inclined to take risks, but didn't have those problems. Which country had a more shadow market problems?
++++++++++
output: Booneland

Please answer this: The strength of an acid refers to its ability or tendency to lose a proton. A strong acid is one that completely dissociates in water; in other words, one mole of a strong acid HA dissolves in water yielding one mole of H+ and one mole of the conjugate base, A, and none of the protonated acid HA. In contrast, a weak acid only partially dissociates and at equilibrium both the acid and the conjugate base are in solution. Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO4), nitric acid (HNO3) and sulfuric acid (H2SO4). In water each of these essentially ionizes 100%. The stronger an acid is, the more easily it loses a proton, H+. Two key factors that contribute to the ease of deprotonation are the polarity of the HA bond and the size of atom A, which determines the strength of the HA bond. Acid strengths are also often discussed in terms of the stability of the conjugate base. David is a chemical engineer. Yesterday, he was working on two samples, sample A and sample B. Sample A was a strong acid, and sample B was a weak acid. David needed to find the differences between them. Which would dissociate in water more, sample A or sample B?
++++++++
Answer: sample A

Problem: The major zones in river ecosystems are determined by the river bed's gradient or by the velocity of the current. Faster moving turbulent water typically contains greater concentrations of dissolved oxygen, which supports greater biodiversity than the slow moving water of pools. These distinctions form the basis for the division of rivers into upland and lowland rivers. The food base of streams within riparian forests is mostly derived from the trees, but wider streams and those that lack a canopy derive the majority of their food base from algae. Anadromous fish are also an important source of nutrients. Environmental threats to rivers include loss of water, dams, chemical pollution and introduced species. A dam produces negative effects that continue down the watershed. The most important negative effects are the reduction of spring flooding, which damages wetlands, and the retention of sediment, which leads to loss of deltaic wetlands. Two rivers spring from the same mountain. Olt was a fast moving river, while Mures river was slow moving and deep. Both rivers are very important for the local economies. Which river had a food source mostly derived from the trees?

A: Olt

Problem: Given the question: In the wiring of a building, the wires carrying the current in and out are different and never touch directly. The charge passing through the circuit always passes through an appliance (which acts as a resistor) or through another resistor, which limits the amount of current that can flow through a circuit. Appliances are designed to keep current at a relatively low level for safety purposes. The appropriate voltage and resistance in a circuit keeps the current in control and keeps the circuit safe. It is possible, however, for something to happen that causes the wire bringing the current in to come into contact with either the wire carrying the current out or the ground wire, thus causing what is called a short circuit . In a short circuit, some or all of the resistance is cut out of the circuit allowing the voltage to push a huge current through the wires. Greg is an electrical engineer. He works for an engineering firm that builds houses. Yesterday, Greg was checking two of the houses. He noticed that one of the houses had short circuit. He labeled that as case A. But the other house didn't have short circuit. He labeled that as case B. Which case would see less current pushing through the wires, case A or case B?
++++++++++++++++++++++++++++++++
The answer is:
case B

Problem: Acromyrmex heyeri is a species of leaf-cutter ant, a New World ant of the subfamily Myrmicinae of the genus Acromyrmex. Acromyrmex heyeri workers construct the colonies nest by thatching together cut grass. At temperatures ranging from 2030 C, workers created more openings in the nest thatch as the internal nest temperature goes up as a method of temperature regulation for the colony. The workers will close openings in the nest thatch as the air humidity surrounding the nest decreases to reduce water loss for the colony. Ants are one of the most interesting creatures on earth. David wants to study ants for his biology project. He is specifically interested in ant species Acromyrmex heyeri. This semester he studied this ant in Americas. First day when he studied the ants the temperature was 10 degree Centigrade. In the second day of his study the temperature rose to 25 degree Centigrade. In the third day of his study the air humidity was high. But in the fourth day of his study air humidity dropped. David wants to continue his study of this same ant species in Asia next semester. On the third day would david see the openings in the nest hatch open or closed?

A:
open