Directions: Answer all four questions, which are weighted equally; the suggested time is about 22 minutes for answering each question. Write all your answers on the pages following the questions in this book. Where calculations are required, clearly show how you arrived at your answer. Where explanation or discussion is required, support your answers with relevant information and/or specific examples.
1.Read the following article from the Fremont New Tribune.
(a) Diseases can devastate populations; however, most diseases do not drive their host to extinction. Provide one explanation for why diseases seldom cause extinction.
(b) Dr. Serach suggests that even if the impact of WNS on little brown bat populations can be reduced and the extinction of the species avoided, the bat populations are likely to remain alarmingly small.
(i) Describe TWO threats (other than WNS) to the survival of the bat species if the total number of bats becomes very small.
(ii) If the little brown bat species does not become extinct and can potentially recover, the rate of recovery is likely to be slow. Discuss one aspect of bat biology that might slow the recovery of little brown bat populations to pre-WNS numbers.
(c) Bats are found in ecosystems around the world. Describe TWO ways in which other organisms in an ecosystem could be affected by a decline in a bat population.
(d) The Eastern deciduous forest in which the little brown bats live is an important ecosystem. Identify TWO ecosystem services that forests provide, and explain how each service benefits human society. WNS is an emerging disease in bats. Humans are also subject to emerging diseases, such as Ebola. A recent study suggests that the number of emerging infectious diseases affecting human populations has been steadily increasing in recent decades.
(e) Provide a likely reason for the increase in emerging infectious diseases affecting human populations. Include an explanation for the reason you provided.
2.Iron ores are rocks from which metallic iron can be extracted for steel production. This process involves severalsteps. Iron ore is first mined and then turned into pig iron in a blast furnace, and some rock waste such as silicondioxide is separated out. In the final step, the pig iron is refined into steel using a process that includes reactingthe molten pig iron with oxygen to remove impurities.
(a) Use the data below to respond to the following. For each calculation, show all your work.
(i) Calculate the weight (in tons) of rock waste produced globally each year when iron ore is converted to pig iron.
(ii) Calculate the weight (in tons) of pig iron that could be produced if all of the estimated global iron ore reserves were used for pig iron production.
(iii) Calculate the weight (in tons) of the current global iron ore reserves that would be used to make steel if the current trends continue.
Both iron ore and coal are mined for use in the manufacture of steel. It is estimated that for every ton of steel recycled, 1.25 fewer tons of iron ore and 0.7 fewer tons of coal must be mined. About 80 million tons of steel are recycled each year in North America.
(b) Calculate the weight (in tons) of coal that is conserved each year in North America by recycling steel.Before the year 1900, most mining companies abandoned surface and subsurface coal mine sites once the resource was depleted.
(c) Describe TWO environmental problems that are associated with abandoned coal mine sites.
(d) Describe one method that can be used to mitigate one of the problems you identified in part (c).
(e) Discuss one reason why surface coal mining is generally less expensive than subsurface mining.