Environment Essay

2354 Words Oct 27th, 2012 10 Pages
1. Providing the Definition:

- Deferred costs: costs that are not recognized immediately, but must be paid later

- External costs: the transfer of the costs to society

- Pollution costs: expenses to correct pollution when it is occurred

- Pollution prevention costs: costs to prevent pollutions from happening.

2. What is cost benefit analysis (CBA)? What are the key steps for CBA?
- Cost benefit analysis is a formal quantitative method for assessing the costs and benefits of competing uses of a resource or solutions to a problem and deciding which is the most effective.

There are four key steps for CBA :
- Identification of the project to be evaluated.
- Determination of all impacts, favorable and
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=> Describe the stops and conditions in Natural selection; - Individuals within a species share genetically determined variation, some of variations are useful and others are not. - Organisms within a species produce many more offspring than are needed to replace the parents when they die.
- Excess number of a certain species would lead to shortage in certain resources.
- Because of variation among individuals, some have a greater chance of obtaining needed resources and likelihood of serving and reproducing than others.
- From one generation to generations, individuals showing favorable variation will increase and those having unfavorable variations will decrease.

5. Compare the climax communities and successional communities.

❖ Climax Community

• Mix of species for a long time

• Have many specialized ecological niches

• More kinds of organisms and kind of interaction

• Recycle nutrients and maintain a relatively constant biomass

❖ Successional Community

• Temporary

• More generalized niches

• Less kinds of organisms and interaction

• Accumulate large amount of new materials.

6. Describe of the biomes:

❖ Grassland :

• Climate: seasonal rains and drought

• Precipitation: 50-150 cm per year

+ Plants:

• Grasses, drought-resistant trees, fire

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