Biology_2007_Virtual_Lab_Answer_Key-1

4 on what day did the paramecium aurelia population

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4. On what day did the Paramecium aurelia population reach the carrying capacity of the environment? How do you know? The Paramecium aurelia population reached the carrying capacity on the tenth day, when the number of individual cells per mL had reached the maximum. 5. Explain the differences in the population growth patterns of the two Paramecium species. What does this tell you about how Paramecium aurelia uses available resources? Paramecium aurelia divide faster than Paramecium caudatum. More organisms per mL are able to live when the Paramecium aurelia population reaches the carrying capacity of the environment.
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6. Describe what happened when the Paramecium populations were mixed in the same test tube. Do the results support the principle of competitive exclusion? The results support the principle of competitive exclusion. Paramecium aurelia eliminates Paramecium caudatum in the course of about 16 days. Since the two species do not prey on one another, they must be competing for the same resources necessary for their growth. 7. Explain how this experiment demonstrates that no two species can occupy the same niche. The experiment demonstrates that two species that use the same food supply cannot live together because one species will out-compete the other for resources. Lab 6: Assessing Water Quality Analysis The answers are intended only as samples. Answers also depend on how students completed the lab and on the random data generated by the computer. 1. What are the names of the species of invertebrates used in this experiment? Which of these species was the most tolerant of increased acidity in the aquarium? Which species were the least tolerant? The species include snail, sideswimmer, clam, crayfish, dragonfly nymph, stonefly nymph, leech, tubifex worm, aquatic earthworm, and fairy shrimp. The most tolerant of all the organisms was the tubifex worm. The least tolerant of all the organisms were the snail, clam, and crayfish. 2. Describe how acid rain affects ecosystems. Because all organisms are adapted to survive within a certain pH range, acid rain can affect entire ecosystems. By changing the pH of water, acid rain kills aquatic animals, plants, and other species directly. Acid rain falling on land plants can damage the leaves. Both forests and aquatic habitats are damaged by acid rain. 3 . What is an indicator species? How are indicator species used to assess pollution levels in the environment? An indicator species is an organism that can be used to determine the health of an ecosystem. Indicator species give scientists specific information about the environment. For example, if population numbers of pollution-sensitive species are low, this is a signal that a pollution problem exists. 4. Suppose you are an ecologist studying the effects of acid precipitation on plant life. Describe an experiment you would perform in order to determine which plant species would be a useful indicator species for acid rain pollution.
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