BI301 MIDTERM EXAM 2012
Use this exam to review, and as a guide to what to expect for this year's midterm. Note that course content -- and information -- change from year to year, so if you see unfamiliar material or statistics here, go with what you've been told in class. You can click on Answers to jump to the answer key to this exam. You can also click on highlighted terms or phrases in the questions below to jump to a place in the lecture notes where that topic was addressed (note that some topics are discussed in more than one place; I try to give a link to the primary place!).
(Sorry that the formatting in some of the answer choices is a little wacky in this web version! Also, figures -- graphs -- don't show up here.) ***********************************************************************************************************
BI301 MIDTERM EXAM 2012 -- 82 Points (2 points each question)
1. An ecosystem service is
A. a division of the BLM that focuses on ecosystem management.
B. a division of the US Forest service that focuses on ecosystem management.
C. a new type of consulting firm that specializes in restoration of damaged ecosystems.
D. a function provided by ecosystems (or their components), such as nutrient cycling, regulation of gases in the atmosphere, water purification, or pollination.
E. "nature's way" of establishing positive feedback systems for pest control.
2. The population of the United States in 2012 is about 300 million persons, and the rate of natural increase (%) for the US population in 2012 is 0.5%. What will be the net addition to the US population in 2012, ignoring immigration?
A. The net addition cannot be calculated based on the data given in the question.
B. 1.5 million persons
C. 150 million persons
D. 150,000 persons
3. In terms of its rate of natural increase ("r"), the population of the United States is growing ___________ compared to the populations of most other highly industrialized nations.
C. at the same rate
4. The primary factor responsible for your answer to Question 3, above, is that
A. total fertility rates for US women are higher than replacement level fertility rates.
B. the US population reached ZPG before those in most other industrialized nations.
C. there are so many immigrants into the US.
D. past high fertility in the US has led to us having a relatively large proportion of our population in the reproductive age classes.
E. access to and information about contraception is more available in the US than in most other industrialized nations.
5. Demography is
A. the study of the role of the Democratic Party in influencing environmental legislation.
B. the study of population statistics and dynamics.
C. a branch of geography that deals with environmental destruction.
D. a branch of ecology that assesses ecosystem services.
E. a branch of economics that attempts to place dollar values on ecosystem services.
The following two questions refer to the figure on the right. This figure approximates the trajectory of human population growth over part of its history. (The figure, which doesn't show up in this web version, plotted number of people in the population on the Y-axis, time on the X-axis, and the curve appeared nearly flat early on, but then had a noticeable steepening slope
6. Which change has contributed least to the acceleration in population growth rate over time?
A. Increasing per capita birth rates ("b").
B. Decreasing per capita death rates ("d").
C. Increasing size of the population ("N").
7. Assuming a constant "r" (rate of natural increase), such a curve illustrates
A. linear growth.
B. existential growth.
C. exponential growth.
D. logistic growth.
E. resource-limited growth.
8. If total fertility rates in every nation on Earth immediately dropped to replacement level and stayed there, what would happen to the human population of Earth? The population would
A. stabilize immediately.
B. begin to shrink immediately.
C. continue to grow indefinitely, but at a slightly slower rate than present.
D. continue to grow for two to three generations and then stabilize.
E. continue to grow, but only because of immigration.
9. Population "momentum" describes
A. the absolute birth rate in a population ("B.")
B. the absolute death rate in a population ("D")
C. the influence of current age structure on future population growth.
D. the government's attitude towards a nation's population growth rate.
10. There are three primary ways by which nations whose populations are growing rapidly could decrease their growth rates. Which one of the following is NOT included in that list of tactics?
A. Decrease demand for large numbers of children
B. Meet unmet demand for contraception
C. Encourage earlier marriage and child bearing
D. Decrease population momentum by dropping fertility rates to lower than replacement level, delaying ages of first reproduction, or increasing intervals between successive births
11. What is the carrying capacity of Earth for humans?
A. 4 billion people
B. 7 billion people
C. 14 billion people
D. No set number can be given, because carrying capacity depends on the level of per capita resource use.
12. The per capita birth rate for the US in 2012 is 0.013. What is the crude birth rate for the US in this year?
A. Information given is insufficient to answer the question.
B. It is impolite to refer to crude matters on exams so this question should be ignored.
13. The Green Revolution in agriculture included all but which one of the following changes?
A. Increased reliance on traditional, locally-adapted crop varieties.
B. Increased use of fertilizers.
C. Increased use of irrigation.
D. Increased use of pesticides.
E. Increased use of fossil fuels.
14. The Green Revolution in agriculture allowed huge increases in grain production in many years, but production also tends to be more volatile now than in the past - widespread failures occur in some crops and years. This increased volatility in production results primarily from
A. dependence on volatile fossil fuel supplies.
B. genetic uniformity in the crops and the widespread planting of relatively few varieties.
C. drawing down of groundwater supplies.
D. economic uncertainties in projecting grain prices.
E. a series of drought years followed by several years of unusually cold temperatures.
15. Plant breeders have improved yields of many crop plants as part of the Green Revolution. Which one of the following characteristics have they been unable to change significantly?
A. The proportion of carbohydrate that is allocated to grain vs. to stems, leaves, & roots.
B. The efficiency of photosynthesis itself.
C. Plant resistance to the major, common diseases and pests that affect that crop.
D. Plant responsiveness to fertilizer and water inputs.
E. Plant sensitivity to day length as a "cue" for flowering.
For each of the following agricultural phenomena (Questions 16 - 19), indicate whether the predominant global trend over the past 40 years has been towards:
(A) Increase, (B) Decrease, or (C) no clear upward or downward trend
16. Pesticide use
17. Per capita land area planted to grain
18. Per capita fertilizer application rates
19. World grain yields per hectare
20. The largest input of fossil fuels into US corn production is associated with
A. manufacture and operation of farm machinery.
B. application of pesticides.
C. drying grain after harvest.
D. manufacture of nitrogen fertilizers.
E. pumping irrigation water.
21. A change in one agricultural practice could provide at least two benefits: (1) decreases in the need for inorganic fertilizers and (2) decreases in the need for synthetic pesticides. Which single agricultural practice could be changed to reap both of these benefits?
A. Increase rotation of grain crops with legumes.
B. Use contour plowing rather than plowing up and down hillsides.
C. Increase acreage planted with "green revolution" crop varieties.
D. Expand use of irrigation.
22. Agriculture represents one of the largest non-point sources of water pollution in the US. Fertilizers running off fields can enrich the water bodies into which the runoff flows. The most serious consequence of this "fertilization" for ecosystems in the affected water bodies is
A. increased sunlight penetration into the water.
B. decreased water temperatures.
C. increased water temperatures.
D. decreased dissolved oxygen in the waters.
E. native plants being poisoned by excess nitrogen.
23. As modern agriculture relies increasingly on inorganic fertilizer supplements rather than on organic inputs of fertility to soils, which one of the following changes tends to occur?
A. Infiltration of water into soil increases.
B. Soil aeration decreases.
C. Soil humus content increases.
D. Retention of nutrients in soil increases.
24. What influence have humans had on the global nitrogen budget? Our activities
A. have caused over half of the world's nitrogen to be sequestered deep in the oceans.
B. have greatly increased the concentration of N2 gas in the atmosphere.
C. "fix" at least as much nitrogen each year as do all natural terrestrial sources combined.
D. have reduced by at least 50 percent the rate of biological nitrogen fixation on Earth.
E. have had no detectable effect on nitrogen dynamics as of the year 2012.
25. Which book first brought pesticide impacts on nontarget organisms and ecosystems to the attention of the public?
A. "The Population Bomb"
B. "An Essay on the Principle of Population"
C. "One Earth, One Future"
D. "Silent Spring"
E. "Changing the Global Environment"
26. A "broad-spectrum" pesticide is a pesticide that
A. is persistent.
B. is readily biodegradable.
C. is toxic to a wide range of pests.
D. is inorganic.
E. can be applied using many types of equipment.
27. A solution to one problem can often lead to new problems. For example, in response to concerns about use of persistent pesticides, such as DDT, pesticide manufacturers made new pesticides that are less persistent. These new pesticides often, however,
A. have to be applied at much higher rates per acre, as they tend to be less toxic.
B. cannot be applied using conventional spray machinery.
C. are largely ineffective.
D. can more readily contaminate water supplies because they are more water soluble.
E. taste worse than older types, so consumers won't buy any produce that was treated with them.
Please use information in the following paragraph to answer questions 28 and 29: Farmer Jones says, "I can't figure this out!! I sprayed my apple orchard with insecticide and fungicide every year for the past 10 years. The chemicals worked great at killing pests and diseases in my apples, but I got tired of all that chemical work, so this year I decided to grow my apples without chemical pesticides. What happened? I got fungi and bugs worse than I ever did before I started spraying! Some of them are the same critters that have always given me trouble, but some new kinds are causing trouble too."
28. The term used to describe the "new kinds" of diseases and pests that Farmer Jones refers to is
A. narrow spectrum.
B. broad spectrum.
C. secondary pests.
29. In addition to the "new kinds" of diseases and pests, why were the farmer's pest and disease troubles worse now than before he/she began using pesticides? (Read the situation carefully!!)
A. The fungi and bugs had developed resistance to the pesticides.
B. The pesticides were synthetic.
C. Pesticides weakened the tree's natural resistance.
D. Populations of natural control agents (e.g., predatory insects), were probably reduced.
E. Farmer Jones irrigated the orchard too heavily.
30. Imagine that you are very allergic to peanuts. You attend a potluck dinner, at which many kinds of cookies are served. You ask the host whether any contain peanuts and the host replies,"Oh, I'm pretty sure that none of them do!" You decide, however that you won't eat any cookies, just to be on the safe side. In so doing, you are applying
A. the principle of bioaccumulation.
B. the precautionary principle.
C. the principle of negative momentum.
D. the principle of diminishing returns.
E. the principle that one should always annoy one's hosts
Please use the following diagram to answer Questions 31 - 33. "Crop" is the abundance of the crop that is being attacked, and "Pest" is the abundance of the insect that eats this crop. (The figure doesn't show up in this web version -- just draw one box with a label "crop," and another with a label, "pest" and one arrow running from the crop box to the pest box and another from the pest box to the crop box)
31. What sign ("+" or "-") should be put on the arrow that expresses the influence of crop on pest?
32. What sign ("+" or "-") should be put on the arrow that expresses the influence of pest on crop?
33. This system represents a
A. negative (stabilizing) feedback system.
B. negative (destabilizing) feedback system.
C. positive (stabilizing) feedback system.
D. positive (destabilizing) feedback system.
34. The largest percentage of the grain grown in the US is
A. lost to pests.
B. exported to lesser developed nations.
C. fed to livestock.
D. used directly as human food.
E. used to manufacture ethanol for use in vehicles.
35. A "decreaser" as defined in lecture is
A. a pesticide whose concentration decreases up a food chain.
B. a pesticide that causes decreases in song bird populations.
C. a term used to describe an aquifer from which withdrawals exceed recharge.
D. a plant whose abundance decreases as a result of livestock grazing.
E. a plant whose abundance decreases in the absence of livestock grazing.
36. A lease rate ($ per AUM) in OR for livestock grazing would probably be lowest on ___ land.
37. You are asked to evaluate the condition of three adjacent pieces of semiarid rangeland, to assess which is in the best condition. ("Best condition" is defined here as that which resembles most closely the pre-livestock grazing condition.) Read the brief description of each piece, and indicate which piece ("A", "B" or "C") appears to be in the best condition.
Piece "A": Lush cover by annual herbs and grasses, sparse perennial bunchgrass cover, most soil not covered with "crust" of lichens and algae, streams have few shrubs along their margins.
Piece "B": Lush cover by perennial bunchgrasses, sparse cover by annual herbs and grasses, soil covered with "crust" of algae and lichens, stream margins lined with shrubs.
Piece "C": Essentially no perennial bunchgrasses, sparse cover by annual herbs and grasses, compacted soils, stream margins muddy and devoid of shrubs.
38. As described in lecture, your assigned reading, "Can Cows and Conservation Mix?" suggests that
A. moderate livestock grazing can be a useful conservation tool, in part because the land is then less likely to be subdivided for housing.
B. livestock improve the quality of streams by fertilizing them.
C. cows and conservation definitely cannot mix; cows are just plain bad.
D. rangeland condition improves as grazing increases.
E. fences are useful to wildlife, because they minimize mixing of genes from different subpopulations.
39. "Excessive" soil erosion (erosion at rates greater than rates of formation) can contribute to
A. increased drought-stress for crops growing in the affected area.
B. increased need to apply fertilizers to the affected area
C. eutrophication of water bodies that receive the eroded soils.
D. B & C only.
E. all of the above.
40. Soils over much of the midwestern US, which support some of the highest levels of crop production in the nation, have
A. generally improved in quality as a result of agricultural practices there.
B. lost approximately half of the topsoil that they contained when farming began there.
C. been eroded to the point that experts predict they won't be productive enough to farm within 10 years.
D. become salinized from excessive irrigation.
E. not been noticeably affected by agriculture over the past 100 years.
41. Which statement concerning loss of soil from U.S. agricultural lands best matches reality?
A. Excessive erosion is not a problem on agricultural lands in the U.S.
B. More than 85% of US agricultural lands are so erosion-prone that they should not be farmed.
C. Erosion losses are of concern in steep mountainous regions of the U.S., but not in flatter or gently rolling regions.
D. We currently lose more soil from US agricultural lands than we did during the "dust bowl" of the 1930's.
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This page is maintained by Patricia Muir at Oregon State University. Page last updated Oct 28, 2011.