[Q]: Two colleagues studied human evolution, Dan studied early humans, from around 200,000 years ago, while Bob studied human settlements from 10,000 years ago. Which student learned more about nomadic tribes? Hint: The earliest members of the human species evolved around 200,000 years ago in Africa. Early humans lived in small populations of nomadic hunters and gatherers. Human beings remained in Africa until about 40,000 years ago. After that, they spread throughout Europe, Asia, and Australia. By 10,000 years ago, the first human beings colonized the Americas. During this long period of time, the total number of human beings increased very slowly. Birth rates were fairly high but so were death rates, producing low rates of population growth.
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[A]: Dan

[Q]: Bill and Jane are two farmers. They both had aphid infestation problems over the last few years, so Bill decided to use many types of insecticides in order to keep the aphids under control. He was only partially successful. Jane didn't do anything about it yet, because she has fewer aphids on her farm, but she vows to do so in the near future. Which farmer had more aphids resistant to carbamates? Hint: Insecticide control of aphids is difficult, as they breed rapidly, so even small areas missed may enable the population to recover promptly. Aphids may occupy the undersides of leaves where spray misses them, while systemic insecticides do not move satisfactorily into flower petals. Finally, some aphid species are resistant to common insecticide classes including carbamates, organophosphates, and pyrethroids.For small backyard infestations, spraying plants thoroughly with a strong water jet every few days may be sufficient protection. An insecticidal soap solution can be an effective household remedy to control aphids, but it only kills aphids on contact and has no residual effect. Soap spray may damage plants, especially at higher concentrations or at temperatures above 32 C (90 F); some plant species are sensitive to soap sprays.
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[A]: Bill

[Q]: Dan and Joe studied animals for biology class. Joe had to study predator animals, while Dan studied herbivores and grazers. Which student learned more about rabbits? Hint: 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.
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[A]: Joe

[Q]: A chemist is working in the lab with two beakers, beaker R and beaker T, filled with identical solutions. In her experiment, she is going to pour one liquid into beaker R and the same amount of a different liquid into beaker T. After pouring the liquid into beaker R, there is no noticeable change. Pouring the liquid into beaker T, she observes a change in the liquid. The reaction in which beaker has a lower activation energy? Hint: A catalyst works by providing a lower energy pathway from reactants to products. The use of a catalyst involves intermediate reactions which have lower activation complexes than the original reaction. On a simplified reaction energy diagram, this can be thought of as lowering the activation energy for a given transformation. If the activation energy of a reaction is decreased, more collisions will have enough energy to overcome this lower barrier, so the reactant-to-product transformation will occur more frequently. As a result, the overall reaction rate will be higher than for an identical reaction with a larger activation energy barrier.
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[A]:
beaker T