HW4-2391

From Environmental Technology

CHAPTER 4 QUESTIONS

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2. Describe an example of secondary succession. Begin your description with the specific disturbance that preceded it.

• Secondary succession would be abandoned farmland in southeastern U.S. First the crabgrass starts to dominate the first year after cultivation has ceased. Then during the second year horseweed dominates, out growing the crabgrass because it is a larger plant than the crabgrass. The horseweed doen't dominate very long because its roots doesn't allow the young seedlings to grow. In the third year other weeds, ragweed, and boomsedge overcompete with horseweed. Boomsedge outcompetes with aster because boomsedge is drought-tolerant to where aster is not. In the next 5 to 15 years after cultivation ceases the dominante plants arepines [short-leaf & loblolly pines]. Because pines produce pineneedls and branches that cover the siol it then changes the soil and environment to where it can hold more moisture and eventually gives the dominance to hardwoods like oak trees. The soil holding water is what young oak seedlings need to become established. Plus the hardwoods [oaks] seedlings are more tolerant of shade than the pine trees. This is an example of secondary succession. This describes what events happen when farmland is abandonded after the last cultivation.

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4. Biologists recongnize that the three types of synbiosis are not always clear cut. For example, under certain circumstances mutalism may become commensalism or even parasitism. What type of symbiosis is it if the fungi in mycorrhizae take so much of their host's food that the host cannot reproduce? Explain your answer.

• The type of symbiosis is parasitism because when the parasite[fungi] eat too much of their hosts food it will cause the host not to be able to reproduce. A parasite[fungi] can cause disease or death to a plant, this is called a pathogen. When the fungi cause disease in a plant it can cause the plant to grow more slowly, therefor the fungi eats more of the food the plants provide to the fungi causing the plant to die off because the plant cannot reproduce as quickly as it could if it wasn't diseased.

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5.Why is a realized niche usually narrower or more restricted, than a fundamental niche?

• A realized niche is mase up of the resources and environment it actually uses and when animals live in the habitat of a realized niche their resources are usually in that specific area. To where in a fundamental niche is when an animal lives in a habitat that contains its resources but can relocate to a different habitat where the resou

rces are also available. The realized niche animals cannot relocate because their resources are not available in a different environment, that is why they are restricted or narrowed.

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8.What is the most likely limiting resource for plant and animals in deserts? Explain your answer.

• The most likely limiting resource wuold be water because plant and trees need soil and minerals to grow. Which in turn the animals need waterto drink to survive. Tha animals also need plants and trees to feed on and need for shade, nesting, and places to raise their young.

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11.Some biologists think that protecting Keystone species would help preserve biological diversity in an ecosystem. Explain.

• If a Keystone species were eliminated from an environment then other species that depend on certain keystone species would die down or even be eliminated. Therefor it would send a chain reaction through the ecosystem where the keystone species was eliminated. Because when an animal survives on the keystone species all of the time or some of the time under certain circumstances then the species would die causing other species to die that depended on that peticular species would be gone as well, and so it goes on and on down the food chain. Then there would only be certain species to survive causing the diversity to go down. Scientist think that to keep wide diversity you do not need to remove a keystone species, that they are essential to the ecosystem in that peticular habitat.

CHAPTER 5 QUESTIONS

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8.How have global air temperatures changed in the recent past? How is this change related to the carbon cycle?

• The globial temperatures have risen in the recent past. There is more carbon dioxide in the atmosphere from industries burning more fossil fuels [coal, oil, and natural gas] recently. Between this and a grater combustion of wood as a fuel and the burning of large sections of tropical forests has released carbon monoxide into the atmosphere at a greater rate than the carbon cycle can handle. This could cause the death of forests, extinction in organisms, a rise in sea levels, and changes in precipitation patterns and could cause problems for the agriculture. It could also cause people to move away from the coastal regions.

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12.What are the two lower layers of the atmosphere? Cite atleast two differences between them.

• The troposphere[1st layer] and the stratosphere[2nd layer]. In the troposphere there is turbulant winds, to where there is also wind in the stratosphere but they are not turbulance winds. In the tratosphere the temperature decreases with increasing altitude from -6'C for every kilometer, to where in the stratosphere it contains a layer of ozone where it absorbes much of the sun's ultraviolet radiation. This heats up the air and so temperatures increases with increasing altitudes, opposite from the tratosphere.

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14.How do ocean currents affect climate on land?

• The wind from the atmosphere affect ocean currents and heat from the ocean currents affect the atmospheric cirrculation. In El Nino [a cirrculation in ocean currents] causes some areas to be drier, some wetter, some cooler, and some warmer than usual. In the northern parts of the U.S. it is warmer in the winter and southern areas of the U.S. are cooler and wetter. High surface-water temperatures cause evaporation of vast quantities of water from tropical parts of the ocean, and the prevailing winds blow the resulting moist air to rise. As it rises the air cools and its moisture-holding ability decreases. When the air reaches its saturation point, clouds form and water is released as precipitation over landmasses.

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16.Relate the locations of earthquakes to plate tectonics.

• Where plate tectonics meet another plate tectonic it is called a plate boundary. When the plates shift or move in any direction it causes earthquakes especially in San Francisco where two plate tectonics meet, therefor causing more effective earthquakes there than any where else in the U.S.

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17.Evaluate the area where you live with respect to natural dangers. Is there a threat of possible earthquakes, volcanic eruptions, hurricanes, tornadoes,or tsunamis?

• There is a possibility of earthquakes in Illinois because we live on a faultline. A volcanic eruption is more than likely not to happen because we don not live where two plate tectonics meet. We don't live on a coastal region so a hurricane wouldn't hit us directly but could indirectly, from thunderstorms, rain, and winds. A tornado is very likely because when hot air mixes with cooler air it forms a tornado. The wind blows a lot in Illinois and comes from all different directions. When it comes from different directions, the air from one direction is going to be cooler than a wind that comes from another direction [north & south winds] which causes tornadoes when the winds mix. If a tsunami hit the eastern coast it more than likely wouldn't affect Illinois. But if a tsunami were to hit arround the gulf of mexico where the Mississippi River is it could affet Illinois by the salty water running into the Mississippi River [fresh water]. Therefor it could contaminate the habitat for animals and wildlife, along with gas and oil from cars and boats that were torn up in the process. But it is not as likely as a tornado would be.