[Q]: In grassland, much of the organic matter added to the soil is from the deep, fibrous, grass root systems. By contrast, tree leaves falling on the forest floor are the principal source of soil organic matter in the forest. Another difference is the frequent occurrence in the grasslands of fires that destroy large amounts of aboveground material but stimulate even greater contributions from roots. Also, the much greater acidity under any forests inhibits the action of certain soil organisms that otherwise would mix much of the surface litter into the mineral soil. As a result, the soils under grasslands generally develop a thicker A horizon with a deeper distribution of organic matter than in comparable soils under forests, which characteristically store most of their organic matter in the forest floor (O horizon) and thin A horizon. Two pedologists studied different types of soil. Yun studied forest soils, while Jian studied grassland soil. They were both very surprised with they findings. Which scientist read less about grassland fires?
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[A]: Yun

[Q]: In the long term, the greatest changes in the Solar System will come from changes in the Sun itself as it ages. As the Sun burns through its supply of hydrogen fuel, it gets hotter and burns the remaining fuel even faster. As a result, the Sun is growing brighter at a rate of ten percent every 1.1 billion years. In about 600 million years, the Sun brightness will have disrupted the Carbon Cycle to the point that trees and forests (C3 photosynthetic plant life) will no longer be able to survive and in around 800 million years, the Sun will have killed all complex life on the Earth's surface and in the oceans. In 1.1 billion years' time, the Sun's increased radiation output will cause its circumstellar habitable zone to move outwards, making the Earth's surface too hot for liquid water to exist there naturally. At this point, all life will be reduced to single celled organisms. Evaporation of water, a potent greenhouse gas, from the oceans' surface could accelerate temperature increase, potentially ending all life on Earth even sooner. During this time, it is possible that as Mars's surface temperature gradually rises, carbon dioxide and water currently frozen under the surface regolith will release into the atmosphere, creating a greenhouse effect that will heat the planet until it achieves conditions parallel to Earth today, providing a potential future abode for life. By 3.5 billion years from now, Earth's surface conditions will be similar to those of Venus today. Rob knows a brilliant scientist who has made a time machine. One day, the scientist let Rob travel time with his machine. Rob noticed that the machine had four gears, gear A, gear B, gear C, and gear D. Rob started with Gear A, which represented the present time. Then he pushed the gear to gear B, which was 600 million years from now. Then he further pushed the gear to gear C, which brought him to 800 million years from now. Finally, he pushed the gear to gear D, which brought him to 1.1 billion years from now. Though he traveled time, Rob was always on Earth all the time. Would Rob see less or more complex organisms in gear B than in gear C?
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[A]: more

[Q]: Another major cause of extinction is global warming , which is also known as global climate change. During the past century, the Earth's average temperature has risen by almost 1C (about 1.3F). You may not think that is significant, but to organisms that live in the wild and are constantly adapting to their environments, any climate change can be hazardous. Recall that burning fossil fuels releases gasses into the atmosphere that warm the Earth. Our increased use of fossil fuels, such as coal and oil, is changing the Earth's climate. Any long-term change in the climate can destroy the habitat of a species. Even a brief change in climate may be too stressful for an organism to survive. For example, if the seas increase in temperature, even briefly, it may be too warm for certain types of fish to reproduce. Ken and Stacy are two engineers discussing their plans about what source of energy they should use to generate electricity in a new city they are helping design. Ken feels that they should use coal since it's reliable, abundant and relatively cheap. Stacy argues that they should use solar power because there is an infinite supply of solar energy. Which person's plan will contribute less to global warming?
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[A]: Stacy

[Q]: Some species of ants farm aphids, protecting them on the plants where they are feeding, and consuming the honeydew the aphids release from the terminations of their alimentary canals. This is a mutualistic relationship, with these dairying ants milking the aphids by stroking them with their antennae. Although mutualistic, the feeding behaviour of aphids is altered by ant attendance. Aphids attended by ants tend to increase the production of honeydew in smaller drops with a greater concentration of amino acids.Some farming ant species gather and store the aphid eggs in their nests over the winter. In the spring, the ants carry the newly hatched aphids back to the plants. Some species of dairying ants (such as the European yellow meadow ant, Lasius flavus) manage large herds of aphids that feed on roots of plants in the ant colony. Queens leaving to start a new colony take an aphid egg to found a new herd of underground aphids in the new colony. These farming ants protect the aphids by fighting off aphid predators. Hannah and Joe are two colleagues. They both study horticulture. They've been studying ants lately for their entomology class. Hannah studied ants that farm aphids, while Joe studied ants that farm fungus. Which student learned more about ants that manage large herds of aphids ?
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[A]:
Hannah