NAME: _____________________________
STUDENT #: _______________
Please note the following:
1.
2.
3.
4.
This is a closed book exam; Non-programmable calculators ONLY are permitted.
Write your name and student number legibly on every exam page.
Write neatly. If we can’t read it, we will not mark it.
Please ensure you uphold all academic honesty rules.
SECTION I: Multiple choice: Circle the single best answer
1. The boreal forest of Canada is:
a. mostly old-growth forest on nutrient-poor soils.
b. variable in age due to moose grazing and grows on nutrient-poor soils.
c. variable in age due to forest fires and grows on nutrient-poor soils.
d. variable in age due to logging and grows on nutrient-rich soils.
e. mostly old-growth forest on nutrient-poor soils.
2. Around Dunedin, New Zealand (in the southern hemisphere), vegetation on north-facing slopes is
like:
a. vegetation from north-facing slopes much further north.
b. vegetation from south-facing slopes much further south.
c. vegetation from much further north.
d. vegetation from much further south.
e. vegetation from the tops of hills further south.
3. What does “fishing down the food chain” mean?
a. Fishing depletes top trophic levels, forcing increasing reliance on lower trophic levels.
b. Overfishing at lower trophic levels, leading to increased exploitation of top predators.
c. The tendency for predators to consume prey at lower trophic levels.
d. A pattern of fishing that depletes all fish from an area.
e. A pattern of fishing that tracks fish along coastlines.
4. Given a hypothesis that “warmer winter temperatures reduce death rates of mosquitoes”, which of
the following observations support that hypothesis?
i. mosquito larvae die less frequently in very cold winter weather.
ii. mosquito adults die more frequently in very hot summer weather.
iii. mosquito larvae die more frequently in very cold winter weather.
iv. mosquito adults die more frequently in warm winter weather.
v. mosquito larvae are more abundant in Labrador than the United Kingdom.
a.
b.
c.
d.
e.
f.
i is true
ii is true
iii is true
i and ii are true
i, ii, and v are true
iv and v are true
NAME: _____________________________
STUDENT #: _______________
5. A biologist knows that the loss of predators causes deer populations to increase. The biologist
observes that deer populations have increased and concludes that predators have been lost. This is
an example of:
a.
b.
c.
d.
e.
Deductive reasoning
Affirming the consequent
Denying the antecedent
An unsuccessful prediction
Inductive reasoning.
6. An ecologist observes that the mean trophic level of fish caught by humans in a particular part of
the Pacific Ocean declines significantly from 3.1 to 2.3 over a 20 year study period. This probably
suggests that:
a. fish species at high trophic levels are decreasing in abundance because of the fishery.
b. fish species at high trophic levels are increasing in abundance because of the fishery.
c. human fishing activities can continue at this intensity indefinitely.
d. carnivorous fish have shifted their life history characteristics to become herbivores.
e. fish species at low trophic level are increasing in abundance because of the fishery.
7. A scientist observes low plant species richness in an environment that is subject to high ultraviolet
radiation. She develops a hypothesis stating that plant species richness generally declines with
increasing ultraviolet radiation. She predicts that low UV environments will have greater plant
species richness than high UV environments, all other factors being equal. Which of the following
best describes the reasoning processes she has followed:
a. The use of inductive reasoning to develop the hypothesis and predictions.
b. The use of deductive reasoning to develop the hypothesis and inductive reasoning to
develop the predictions.
c. The use of inductive reasoning to develop the hypothesis and deductive reasoning to
develop the predictions.
d. The use of deductive reasoning to develop the hypothesis and predictions.
e. The use of inductive reasoning to eliminate the impossible, leaving only the possible,
however unlikely.
8. A biologist must decide which of two hypotheses is more successful. If Hypothesis 1 is true,
predictions A and B must be observed. If Hypothesis 2 is true, predictions B, C, and D must be
observed. The biologist observes the following: A is true, B is false, C is true, and D is true. What
should the biologist conclude about the two hypotheses?
a. Hypothesis 1 and Hypothesis 2 are both true but Hypothesis 1 is more successful.
b. Hypothesis 1 is false but Hypothesis 2 is true.
c. Hypothesis 1 is true but Hypothesis 2 is false.
d. Hypothesis 1 and Hypothesis 2 are both false.
e. Hypothesis 1 and Hypothesis 2 are both true but Hypothesis 2 is more successful.
NAME: _____________________________
STUDENT #: _______________
9. A biologist is interested in determining how the abundance of a mammal species is affected by
particular environmental characteristics. She measures net primary productivity, mammal
population size, minimum temperature during mating season, and nutrient availability in the
vegetation. In this study:
a. net primary productivity and mammal population size are dependent variables and
minimum temperature and nutrient availability are independent variables.
b. mammal population size is the independent and all others are dependent variables.
c. net primary productivity is the independent and all others are predictor variables.
d. nutrient availability is the independent variable and other variables are irrelevant.
e. mammal population size is the dependent and all other variables are predictor
variables.
***
The following two questions use the information given below.
A biologist samples the abundance of two plant species and counts the number of individuals of both
species in five different quadrats. Each quadrat is 2m2 and the total habitat area is 2000m2.
Quadrat
Individuals of plants species 1
Individuals of plants species 2
1
6
9
2
5
26
3
7
4
4
7
0
5
5
1
10. The overall abundances of the two species in this area are about: (ANSWER is 6000 for species 1
and 8000 for species 2, so if someone fills this in correctly anywhere, mark as correct)
a. cannot be estimated without additional information.
b. 8000 for species 2 and 9000 for species 1.
c. 5000 for species 2 and 6000 for species 1.
d. 9000 for species 2 and 3000 for species 1.
e. 4500 for species 2 and 4500 for species 1.
11. The population structure and variance of species 2 is:
a. random with a variance of 90.8.
b. clumped with a variance of 113.5.
c. uniform with a variance of 454.
d. random with a variance of 90.8.
e. clumped with a variance of 454.
***
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12. An ecologist is measuring the rate at which a plant species grows. There are three groups of this
plant species. He adds carbon to the first group of plants and observes a 13% increase in plant
growth. He adds nitrogen to the second group of plants and observes an 8% increase in growth
rates. He adds nitrogen and carbon to the third group of plants and observes an 19% increase in
growth rates. Which nutrients are most limiting in this experiment?
a. Nitrogen is the most limiting nutrient, followed by carbon.
b. Carbon is the most limiting nutrient, followed by nitrogen.
c. Nitrogen and carbon are equally limiting.
d. Nitrogen and carbon are equally limiting but a third nutrient is clearly missing.
NAME: _____________________________
STUDENT #: _______________
e. Results are too uncertain to say which nutrient is most limiting.
13. Parasite species A lives on 100% of potential hosts. A second, similar parasite species (“species
B”) arrives in the area. The next year, species A lives on 38% of hosts and species B lives on 62%
of hosts. What has happened?
a. The fundamental niche of species B is too small to allow it to occupy the whole area.
b. The realized niche of species A is smaller than that of species B.
c. The fundamental niche of species A declines in the presence of species B.
d. The realized niche of species A is much smaller than its fundamental niche when
species B is present.
e. The fundamental niche of species B expanded and species B declined as a result.
14. Coral species often tolerate a small range of water temperatures. Climate change is causing large
water temperature increases, causing some coral species to disperse toward cooler waters. Coral
species are most likely to avoid extinction due to climate change if:
a. climate warms quickly and coral dispersal rates are low.
b. climate warms slowly and coral dispersal rates are high.
c. climate warms slowly. Coral dispersal rate does not matter.
d. climate warms quickly and coral dispersal rates are high.
e. climate warms quickly. Coral dispersal does not matter.
***
15. Hadley cells cause: (DO NOT MARK THIS QUESTION)
a. precipitation to decrease at the equator but increase toward the edge of the tropics.
b. precipitation to increase in terrestrial areas and decline over oceans.
c. solar radiation to decrease at the edge of the tropics and increase toward the equator.
d. Coriolis forces to change the prevailing winds at the equator to come from the west.
e. warm ocean currents that give Labrador and Newfoundland long summers.
16. Climatic conditions in the central Amazon basin of Brazil are warm, moist, and often cloudy.
Climate change is expected to cause the area to become sunnier and drier. Net primary
productivity is limited by:
a. solar radiation but may become temperature limited in the future.
b. temperature but may become moisture limited in the future.
c. solar radiation but may become cloud limited in the future.
d. temperature and likely to remain that way in the future.
e. solar radiation but may be limited by moisture in the future.
17. Plants require CO2 for photosynthesis. Atmospheric concentrations of CO2 have been increasing
since the start of the industrial revolution but plant growth is not faster than when plants are grown
with pre-industrial atmospheric concentrations of CO2. Which of the following hypotheses is most
likely to explain why this is so?
a. Water is limiting when the climate is warmer.
b. Plants grow best when they allocate resources to their roots.
c. CO2 is not the primary limiting nutrient for plants.
d. Slight increases in CO2 concentration actually inhibit plant photosynthesis.
e. Plants did not evolve under high CO2 conditions and cannot use extra CO2.
NAME: _____________________________
STUDENT #: _______________
18. In an area with high primary productivity at all times of year, it would be surprising to find a plant
species with:
a. defenses against herbivores.
b. woody stems.
c. freeze tolerance.
d. extensive root systems.
e. a and c are both correct.
***
19. The epilimnion of a lake can best be described as follows:
a. the cool, shallow part of a lake without thermal stratification.
b. the warm, shallow part of a lake with low rates of photosynthesis.
c. the warm, deep part of a lake with thermal stratification.
d. the cool, deep part of a lake beyond the metalimnion.
e. the warm part of a thermally stratified lake with high photosynthesis rates.
20. A biologist observes photosynthetic rates in two lakes. In Lake 1, algae are photosynthesizing at a
rate of 4 units/hour at a depth of 2.5 metres. In Lake 2, the algae are photosynthesizing at 4.2
units/hour at a depth of 0.3 metres. Explain the differences between the two lakes.
a. the first lake has a deeper compensation level.
b. the second lake has a deeper euphotic zone.
c. the first lake has greater nutrient availability.
d. the second lake is unstratified.
e. the first lake is unstratified.
21. Logistic population growth:
a. Appears to be exponential as low K decreases as K approaches N
b. Appears to be exponential at low N but increases as N approaches K
c. Grows until N is exceeded and then crashes
d. Grows almost exponentially when N/K approaches 0 but slows as N approaches K
e. Grows until K is exceeded and then crashes
NAME: _____________________________
STUDENT #: _______________
SECTION II: Short answer. Use only the space provided to answer FOUR (4)
questions from the list of FIVE (5) that follow. Each question is worth 4 marks. If you
answer all five questions, you will be marked on the first four only.
1. An ecologist observes the decline of light intensity with depth in two lakes. In Lake 1, she finds
that the light intensity at the surface is 200 W/m2 but that this light intensity declines by 50% in the
first meter.
a. (2 marks) What is the light intensity in Lake 1 at a depth of 6 metres? Show your complete
calculations.
I Z  I 0 e  kZ
I
ln  Z
 I0

  kZ

So, light intensity drops by 50% in the first metre in lake 1. So, ln(0.5) = -kZ. Z = 1 metre, so
k = -ln(0.5). k = 0.693.
Therefore light intensity at 6 metres will be 200 X e-0.693 X 6 = 3.13 W/m2
b. (2 marks) Light intensity in the Lake 2 is 10% of the surface light intensity (which is 200
W/m2) at a depth of 2 metres. Describe the likely phosphorus concentration of the second
lake relative to the first lake. Be sure to explain your reasoning fully.
Light intensity drops off a good deal faster in the second lake (1 mark – could also present calculations
showing that this is true). This is almost certainly because of much greater chlorophyll (or phytoplankton
or algae, etc) concentrations in the water, which means that phosphorus concentrations are likely to be
significantly higher (1 mark).
2. (4 marks) A scientist creates two hypotheses. The first hypothesis states that butterfly population size
around Ottawa increases with increasing net primary production. The second hypothesis states that
butterfly population sizes is a function of net primary productivity, mean summer temperature, pesticide
use, and summer precipitation levels. The scientist fully tests both hypotheses and finds that she can
predict butterfly population sizes with an R2 of 0.71 for both hypotheses. Which hypothesis is better from
a scientific perspective? Explain why.
The two hypotheses have exactly the same predictive power (1 mark). However, the second hypothesis is
way more complex, which violates Ockham’s razor (the law of parsimony), which demands that the
simpler hypothesis be the better hypothesis, all other things being equal (1 mark). In this case, the second
hypothesis has one factor in common with the first hypothesis: net primary production. The addition of a
bunch of other factors, like mean summer temperature, and so on, do nothing to improve the model
results. This means that those other factors are probably not even significant predictors of butterfly
richness. (2 marks for demonstrating significant understanding of this last point).
NAME: _____________________________
STUDENT #: _______________
(4 marks) Consider the annual climatic data for the following two locations:
Location 1
Location 2
Precipitation (in millimeters)
February
May
August
400mm
450mm
700mm
200mm
40mm
20mm
November
390mm
150mm
Location 1
Location 2
Temperature (in 0C)
February
May
19
23
24
31
November
21
23
August
25
35
Describe the likely vegetation in both locations. Explain. In August, what is the main limit on NPP in both
areas?
The first place is warm and very wet and stays that way pretty much all year round. It probably has very
high biomass vegetation, like tropical rainforest (1 mark). The second place is warm to very hot and has
little precipitation at the hottest time of year. It will certainly have very sparse vegetation and be some
kind of desert. (1 mark). The main limit on NPP in the first location is likely to be solar radiation – that
place is really WET! (1 mark) The second place is definitely going to be limited by water availability or
precipitation. (1 mark).
4. (4 marks) Describe the key biological characteristics of the mixed wood plains ecozone. Why are there
more endangered species in this ecozone than in other parts of Canada? Name an endangered species
found in this area.
(students must get at least two of the following characteristics for two marks)
-mild winters, mean T in January around -3 to -12 deg C
-fairly humid
-good soils
- historically covered by Champlain Sea, which deposited lots of marine sediements.
- soils are well-drained
- dominant herbivore is deer
- pretty high diversity
Lots of endangered species because:
- there are lots of species in the area to start with and human activities of
various kinds of very intensive throughout the ecozone.(1 mark)
- Examples of endangered species: massassauga rattlesnake, karner blue
butterfly, spiny softshell turtle, etc.(1 mark)
NAME: _____________________________
STUDENT #: _______________
5. Provide a detailed explanation of the hypothesis that “mountain passes are higher in the tropics”
and how it might help explain global patterns of species diversity.
In this hypothesis (which is not necessarily correct, although students don’t need to point that out), the
climatic differences between the base of a mountain range and a high altitude pass through the mountains
will be very large in the tropics. For instance, at the base of the Andes in Peru, there is warm, humid
tropical forest. In the mountain passes through the Andes, climatic conditions can be very cold, and be
outside the range of climatic conditions that species ever experience in the tropical forests below. This
creates isolation around mountain ranges in the tropics and the potential for greater diversification. In
temperate to cold areas, species living at the base of mountain ranges will experience cold winters, which
means that those species would be better able to tolerate cold temperatures compared with their tropical
counterparts. Isolation is harder if species can cross barriers more easily and therefore speciation would
be liable to be less in colder areas. (4 marks for any explanation that sounds about this inclusive and
detailed or better)