Biology 230, Sections 101/102 – Final Exam Preparation Document, November 2012
Short-answer questions (¼-page of space provided, 5 marks each)
One style for these is - Define, or explain briefly, or distinguish: whatever.
In addition to the more recent terms here, we refer you to learning outcomes and other slides in Power Point presentations, where
all appropriate terms are listed/highlighted/defined. All terms for the course are fair game!
Ecosystem services Residence time Keystone species
Habitat degradation Weather, Climate Geochemical
Habitat loss Greenhouse effect Watershed or Catchment
Exotic or Invasive species Acid rain Turnover rate
Endemic species Biodiversity Anthropogenic
Nutrient cycle Habitat fragmentation Climate change
Biogeochemical cycles Taxonomic homogenization Greenhouse gases
Nutrient Pool Indigenous species
1. Explain why some of the world’s most productive forests (tropical rain fores ts) can persist on some of the world’s poorest
2. Would you expect specialist-diet or generalist-diet herbivores to be more strongly affected by spatial patchiness of their plant
prey-type(s)? Argue for ONE option only, stating assumptions.
3. In some ways – especially by consuming only small portions of the live host/prey, rather than killing it first – parasites on (or
inside) animals are analogous to herbivores on plants. Does this imply that parasite abundance is controlled by predation, in
the manner suggested for the control of herbivores by HSS theory? Make EITHER a “yes” OR a “no” argument (not both), and
4. Name and briefly explain three physical consequences on the world resulting from climate change.
5. Briefly explain (a diagram could help) why tropical forest vegetation may be more vulnerable to climate warming than boreal
6. Explain briefly how diet-switching by a foraging animal population could relate to prey diversity (and/or biodiversity) in the
area occupied by that forager-population; your answer will demonstrate an understanding of frequency-dependent selection.
7. Some prey animals (like our old lab friends, terrestrial isopods) are largely protected from predation because they secrete in
their tissues bad-tasting, mildly-poisonous chemical compounds... but this has not allowed them to breed uncontrollably and
become superabundant, so the benefit of protection must also have a cost. Suggest ONE specific cost of this protection-by-
toxicity benefit; state your cost-idea in the form of a testable hypothesis deriving from theory, and state assumptions.
Half-page questions (10 marks each)
8. Some predators (such as baleen whales, and web -building spiders) exhibit a style of
prey-capture behaviour known as a Ty pe 1 functional response (as illustrated in the
graph at left).
a. Describe in biological ( not mathematical) terms the behaviour of a Type 1 forager as
shown on the graph. (5 marks)
b. In any type of functional response (Types 1, 2, or 3), there is alway s a “plateau”
number of prey caught when N is high; why? (5 marks)
2 Biology 230, Sections 101/102 – Final Exam Preparation Document, November 2012
9. One proposed explanation of high species -richness in the Tropics compared to other areas of the Earth is the “Productivity
a. describe briefly the mechanism by which the Productivity Hypothesis is supposed to work (4 marks).
b. is the Productivity Hypothesis a deterministic or a stochastic theory? Select ONE choice, and justify (6 marks).
10. In order to avoid constructing an expensive addition to a city’s wastewate r treatment plant, a city engineer suggests that after
removing suspended solids and noxious chemicals, the wastewater could be spread on a scrub forest and permanently solve
two major problems. He reasoned that the remaining organic matter in the wastewa ter would be broken down by decomposers
(e.g. soil fungi and bacteria), and excess inorganic nutrients would be taken up by forest plants, thereby preventing
eutrophication (i.e. overfertilizing)ofastreamwhichcurrentlyreceivedthenutrients. Asidef rom aesthetic considerations,
where has the engineer gone wrong in his thinking? (10 marks)
11. Suppose that a “pulse” of nutrients was added to a lake in each of two consecutive years. In both years, measurements of
nutrient pool sizes in the phytoplankton, herbivores, predators and detritivores were made 1 week before and 1 week after the
pulse. Offer an explanation for the following observations made one week after the pulse was added (note: “increase”,
“decrease”, and “no change” refer to the observed c hanges compared to the pre-pulse conditions for that particular year):
• Year 1: phytoplankton and detritivores both increase, but no change in herbivores and predators.
• Year 2: Phytoplankton and herbivores both decrease, but predators and detritivores both increase.
12. In marginal-value (“patch-use”) foraging theory, the optimal leaving -time from a patch (in a given case of forager/patch-
distribution/prey-abundance) is set by a tangent-line with a particular slope.
a. Explain what the units of this slope are(2 marks), and briefly why the slope makes an appropriate “deciding-value” for the
foraging animal. (3 marks) (5 marks total for part a.)
b. Imagine that you measured the normal parameters of the model for a real forager and food -patch situation in the lab (as you
might with e.g. abeeforagingonflowers),butwhenyouobservedtheforager’sbehaviourinthefielditleftpatches
consistently sooner than the model predicts. Provide ONE specific reason why a forager might act this way, stated in the form
of a hypothesis deriving from theory, with assumptions. (5 marks)
13. Consider the following argument: “The reason the that Atlantic coast of Canada supports so few species of intertidal
barnacles, mussels, snails, and other sedentary or slow -moving herbivores c ompared to the Pacific coast is that predators (such
as seastars) are rare on the Atlantic coast, thereby permitting only a few dominant herbivores to succeed.” Describe an
experiment that you would perform to test this idea about controlling factors in th ese intertidal communities. State
14. Give 5 reasons for the successful invasions of exotic species. Illustrate each with an example.
15. The “green world” (HSS) and Menge -Sutherland (M-S) models both seek to explain community structure as a consequ ence of
tradeoffs among the influences of competition, predation, and abiotic forces.
a. What is the major difference between the models (H INT – it concerns mainly the competition/predation tradeoff), and why
did the M-S authors decide it was a necessary c hange? (4 marks)
b. What role is played in the model(s) by omnivory? (3 marks)
c. What role is played in the model(s) by recruitment? (3 marks)
Full page questions (10 or 15 marks each)
16. What might the consequences of deforestation be on: (in a 15 -mark version you would be asked for 5 of these, or others; in a
10-mark version, 3 or 4)
• stream flow
• nutrient loss from an ecosystem
• soil stability
• decomposition rates
• nutrient cycling rates
• fish habitat
3 Biology 230, Sections 101/102 – Final Exam Preparation Document, November 2012
17. In the Kluane Boreal Forest Ecosystem Project in the southern Yukon, some plots in the understorey were treated with
fertilizer for 20 years, while others were fenced to eliminate or reduce herbivores for 20 years, yet others received both
fencing and fertilizer, and of course there was also a control, treatment. In the table below, indicate what biomass responses
you would predict to occur in the understorey plant community in the three treatment plots (the data are corrected for changes
in the control plots), if they are (a) under strict bo ttom-up regulation, and (b) under strict top -down regulation. Note that the
question is not asking about both bottom-up and top-down acting simultaneously. In plots where you predict a change in
biomass, explain what might be happening to the species compo sition of those plots.