HW4-2391
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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. | + | *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. | ||
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| + | *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? | ||
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| + | *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. | ||
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| + | *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. | ||
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| + | *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. | ||
Revision as of 18:37, 21 February 2006
CHAPTER 4 QUESTIONS
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.
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.
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.
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.
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.
