Ecology Exam I Essay Questions
Chapters 1, 2, 3, 4, 5, 6, 7, and 10 will be on the exam. Chapters 8 and 9 are extra
credit. Questions from 8 and 9 will not be listed below. Questions for chapters 8 and 9
could be essay and/or multiple choice and/or fill in the blank. The exam is broken into
multiple choice questions, fill-in-the-blank questions, and essay questions. The questions
range from the easy to the difficult.
The list below is a list of all potential questions. Any essay question to be asked (with the
exception of questions on chapters 8 and 9) will come from this list.
Ecology students in Public Health may be asked questions about climate change not listed
below but based on the climate change lecture at the AUB.
1. Questions could be included which challenge you to think about how ecologists
study and learn about the natural world. The emphasis of these questions is on
application of the scientific method.
2. Why do animals and plants exchange energy and materials differently, internally
and externally, respectively?
3. What is a dynamic steady state, and what are the costs in maintaining it, and how
are those costs met?
4. Scientists ask questions about how the natural world works. These questions can
usually be classified as "how" questions and "why" questions. Compare and
contrast these fundamentally different kinds of questions.
5. How are humans an important part of the biosphere?
6. What are some recent events that indicate the ability of humans to respond in a
positive and successful way to environmental problems?
7. You could be asked questions on a hypothetical on-site assessment of water
quality in a stream that would test your knowledge of the properties of water.
8. Explain the following quotation through use of examples: ‘the physical world
provides the context for life but also constrains its expression.’
9. What is acidity in aquatic systems and how is the acidity of water commonly
expressed? Why do ecologists typically determine the acidity of aquatic systems?
10. Why is there an imbalance between the gain of carbon dioxide and the loss of
water?
11. Why is the coupling of the oxidation/reduction of carbon and oxygen in the
processes of photosynthesis and respiration of fundamental importance to all
living things?
12. Why do smaller animals typically use higher pitched sounds for sensing the
direction of a sound source?
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13. You could be asked questions that would challenge you to put to work some of the
things you have learned about adaptations of animals to their environments. So,
understand the energy budgets of animals.
14. What conflicts arise when plants meet their dual needs of obtaining carbon
dioxide from the atmosphere while conserving water?
15. Compare and contrast the challenges faced by fresh-water aquatic and terrestrial
animals from the perspective of water balance.
16. What are the costs vs. benefits of homeostatic regulation of internal conditions?
17. Is there a general rule that governs the rate of flux of heat or materials between an
organism's tissues and the external environment? If so, what is it?
18. Why is adaptation to the environment a compromise?
19. Based on your understanding of larger-scale patterns of climatic variation and
their causes, imagine you are a regional climatologist, with special expertise in
Western Hemisphere climates. You are, in a sense, a "climate forecaster," using
your understanding of past and present climate to help others plan for the future.
Review climatic variation enough to be able to answer questions about
intertropical convergence, seasonal variation in climate, and El Niño.
20. Be able to explain this quotation: "The surface of the earth, its waters, and the
atmosphere above it are a giant heat-transforming machine."
21. Explain why biological activity is severely limited in a thermally stratified
temperate lake in mid-summer surface and deeper waters.
22. In the temperate zone of the Northern Hemisphere, south-facing slopes of
mountains are warmer and drier than north-facing slopes at the same elevation;
vegetation growing on these different slopes will reflect the difference in local
climate. Why is this?
23. The physical changes associated with El Niño events can cause cascading
biological events, leading to dramatic fluctuations worldwide in populations of
plants and animals. Describe, in your own words, the ecological consequences of
an El Niño for a particular part of the world.
24. When a mountain range is exposed to prevailing winds from a particular direction,
the windward side of the range (the side facing the prevailing winds) receives more
precipitation than the leeward side (the side facing away from the prevailing
winds). Low-lying areas to the leeward side of the range also tend to be much
drier than areas at similar elevation to the windward side of the range. Explain
these phenomena in detail.
25. Discuss some reasons why community composition changes as one moves (1) up a
mountain and (2) down the continental shelf into the abyssal depths of the ocean.
26. A very wealthy friend of yours has decided to construct a massive indoor "biome
garden," containing representative ecosystems from many parts of the world.
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Your friend is in the early planning stages of this venture and has hired you as an
ecological consultant. Your task is to help solve the many problems associated
with designing greenhouse-style modules with appropriate environmental
conditions for each of the biomes. The biome garden is to be developed where
warm summers alternate with mild winters to create conditions naturally suitable
for the temperate deciduous forest biome. The site chosen for development of the
biome garden is a pine plantation that was established approximately 70 years
ago. The soils are clayey, acidic, relatively infertile, and have low organic matter
content. You are free to make any recommendations for environmental conditions
in the greenhouse modules, regardless of the expense associated with
implementing them. Also, you don't need to worry about how to implement these
conditions. You would need to use your knowledge of biomes (and not just
temperate biomes) to work to answer the questions.
27. The tropical rain forest is a diverse community supported by a nutrient-poor soil.
Why?
28. The biome concept emphasizes the relationships among various growth-forms of
plants and their physical environments. However, two other important factors
influence the distributions of species. What are these? Provide a brief example of
why each of these additional factors must be taken into account.
29. Why do desert trees have small, finely divided leaves, while leaves on trees in
deciduous forests are broad?
30. In Whittaker's diagram relating distribution of the world's biomes to climate
(Figure 5.11), most locations fall within a triangular area. Lacking are many
places that experience cold temperatures combined with high precipitation. Why?
31. Why are deserts more likely to be found at around 30 degrees latitude than at
other latitudes?
32. Why are the forms of plants more responsive to variations in climate than the
forms of animals?
33. Understand the equations for photosynthesis. Example: what is the equation for
net primary productivity? For gross primary productivity?
34. Understand secondary production. How do you determine ingestion and
assimilation? Assimilation efficiency? Net production efficiency? Ecological
efficiency?
35. Why is energy sometimes referred to as the "ecological currency" of an ecosystem?
36. Water is a reactant in the photosynthetic process. However, techniques for
measuring net production focus on the other reactants and products of
photosynthesis, to the exclusion of water. Why is this?
37. Does light limit photosynthesis?
38. Why is ecological efficiency not the same as gross production efficiency?
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39. Understand global cycling of carbon and its relevance to the issue of global
warming.
40. From a thermodynamic perspective, evaporation and condensation of water
resemble photosynthesis and respiration. Please explain.
41. The water cycle can be viewed as an enormous solar-powered pump, transporting
water from earth's oceans to its landmasses, whence the surplus water returns to
the oceans via rivers. Please outline the details of this process.
42. Compare and contrast the paired processes of precipitation/dissolution and
assimilation/dissimilation of carbon in aquatic systems.
43. The symbiosomes of root nodules harboring Rhizobium bacteria contain a special
form of hemoglobin called leghemoglobin. What is the significance of
leghemoglobin for nitrogen fixation in these root nodules?
44. Microorganisms figure prominently in global cycles of many elements. Discuss the
significance of microorganisms in a particular elemental cycle, using specific
examples.
45. In a mark-recapture exercise during which a population of butterflies remained
constant in size, an initial sample provided 70 individuals, each of which was
marked and then released back into the population. Two days later, a second
sample was taken, totaling 321 individuals of which 74 bore a mark from the first
sample. Estimate the size of the population. State any assumptions that you have
had to make in arriving at your estimate.
46. Understand the continuum of ‘slow’ and ‘fast’. In other words, if you were to
catalog the traits for different species, including development rate, age at sexual
maturity, allocation of resources to reproduction, adult mortality rate, and length
of life, and then you were to find these traits will not vary independently of one
another but will instead exhibit correlated changes along a continuum, where
would you place the traits along that continuum? Also, what is the relationship
between sexual maturity and lifespan? What is the relationship between fecundity
and adult mortality?
47. Understand consequences of litter supplementation (i.e. adding eggs to a nest).
48. What are some trade-offs in life history traits?
49. Given a fixed allocation of resources to reproduction, there are still many possible
trade-offs between the size and number of offspring produced. What are those
trade-offs?
50. How can reciprocal transplant experiments help us separate genetic and
environmental contributions to phenotypic variation?
51. Is senescence inevitable? Please explain your answer, accounting for the great
variation in patterns of aging among different species.