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Exam #2A Key - Exam 2 key
Ecology (Binghamton University)
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BIOL 355: Ecology (Sections B and C)
Exam #2 Version A
Fall 2023
Follow these DIRECTIONS for full credit:
1. Fill out the Gradescope Bubble Sheet with:
a. Your full name
b. Your B-Number next to ID
c. Version A, B, C, or D. You can find your version at the top of this page.
2. Write your full name and B-Number on the exam packet.
3. Fill in the appropriate answer on the Bubble Sheet for all multiple choice questions, and
answer the short answer questions completely.
4. After the exam, read and sign the following statement and turn in both the answer sheet and
exam.
By signing below, acknowledge that I have not violated Binghamton University’s academic
honesty policy. I give my word that I have neither cheated on this exam, nor have I knowingly
allowed any other person to cheat on this exam.
NAME________________________________
B#______________________________
Discussion Section:
_
Signature_______________________________
1. A population of mayflies in Fuller Hollow Creek is estimated to be around 1000 adult flies.
The stream can support 500 flies, and the intrinsic rate of growth is 1.5. What will happen to the
population over time?
a. The population will increase to 1500 mayflies.
*b. The population will decrease to hover around the value of 500.
c. The population will remain the same.
d. The population will increase to hover around the value of 500.
e. The population will go extinct.
2. Researchers concluded that a recovering population of buffalo in Montana had a high
survivorship throughout much of the cohort’s lifespan, followed by a drastic increase in
mortality. They estimated that the current habitat can support an exponential growth of the
buffalo due to a mild winter. This is an example of:
*a. Type I survivorship curve
b. Type II survivorship curve
c. Type III survivorship curve
d. Type IV survivorship curve
e. There is not enough information
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3. Researchers concluded that a recovering population of buffalo in Montana had a high
survivorship throughout much of the cohort’s lifespan, followed by a drastic increase in
mortality. They estimated that the current habitat can support an exponential growth of the
buffalo due to a mild winter. This is an example of a:
*a. Density independent population
b. Density dependent population
c. Density co-dependent
d. There is not enough information
e. Extra answer – DO NOT PICK THIS ONE.
4. The following is true about general patterns regarding life history tradeoffs:
a. A population with high fecundity, a fast growth rate, who reaches sexual maturity at a young
age, and produces many offspring, will often have higher survivorship.
b. A population with high fecundity, a fast growth rate, who reaches sexual maturity at a young
age, and produces many offspring, will often have lower survivorship.
c. A population with low survivorship and a slow growth rate will invest in traits that allow them
to compete with other individuals. This is results in lower fecundity.
d. A population with high survivorship and a slow growth rate will invest in traits that allow
them to compete with other individuals. This is results in lower fecundity.
*e. B and D are correct.
5. In terms of species interactions, costs and benefits are measured in terms of:
a. Survivorship
b. Resources
*c. Fitness
d. Rewards
e. Fecundity
6. Intraguild predation is the killing and consumption of a competitor. The relationship between
lions and hyenas is an example of intraguild predation. The largest percentage of hyena infantile
deaths is from lions killing young pups within their dens. Hyenas are known to move pups to
new dens, and preferentially choose dens with dense vegetation, but away from water holes.
Lions now search clusters of dense vegetation for hyena dens. This relationship is best described
as a(n):
a. Mutualism
b. Convergent evolution
*c. Evolutionary arms race
d. Commensalism
e. Mimicry
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Answer Questions 7-9 using the following life table:
Age
Number of Log (#
Survivorship
Class survivors
survivors)
Age-Specific
Fecundity
1
2
3
4
5
0
0
0
0
21.52
13742
5593
4335
2582
1056
4.1
3.7
3.6
3.4
3.0
1
0.41
0.32
0.19
0.08
Average
births/year/original
females
0
0
0
0
1.654
7. First, determine the Net Reproductive Rate for this species. Which of the following statements
is true?
*a. The population is increasing.
b. The population is decreasing.
c. The population is staying the same.
d. We need more information.
e. Extra answer – DO NOT PICK THIS ONE.
8. Which of the following graphs represents a survivorship curve for the table above?
A. 16000
5
B.
Log # of survivors
# of survivors
14000
12000
10000
8000
6000
4000
4
3
2
1
2000
0
0
0
1
2
3
4
0
5
1
2
Age Class
D.
survivorship
1
0.8
0.6
0.4
0.2
0
1
2
3
4
4
5
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
-0.2 0
1
2
3
-0.4
Age Class
5
1.8
Average births/year/original
females
C. 1.2
0
3
Age Class
Age Class
a. Figure A
*b. Figure B
c. Figure C
d. Figure D
e. None of the above.
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5
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9. Based on your survivorship curve for Question 8, this is an example of a:
a. Type I survivorship curve
*b. Type II survivorship curve
c. Type III survivorship curve
d. Type IV survivorship curve
e. There is not enough information
10. According to the logistic growth model, which of the following statements is true?
a. The number of individuals added per unit time is greatest when N approaches K.
b. The per capita growth rate (r) increases as N approaches K.
c. The population grows exponentially when K is small.
*d. population growth is zero when N equals K.
e. More than one answer is correct.
11. Density dependent growth is when population growth slows mainly due to:
a. Scramble competition
b. Interspecific competition
c. Interference competition
*d. Intraspecific competition
e. More than one answer is correct.
12. By transplanting an upper intertidal barnacle species (Chtamalus stellatus) into the lower
intertidal zone dominated by a different lower intertidal species (Balanus balanoides),
researchers concluded that...
*a. Competition resulted in the resource partitioning between the two species.
b. These species can coexist despite occupying the same niche.
c. Competition resulted in lower mortality rates for Chtamalus stellatus in the presence of
Balanus balanoides
d. These two species do not compete for the same resource.
e. The mutualistic relationship can break down when food is scarce.
13. Which of the following is NOT a characteristic of an endoparasitic lifestyle?
*a. Easily move between and among hosts.
b. Low risk of predation for natural predators.
c. High exposure to a host’s immune system.
d. Easily feed on a host.
e. More than one of the above is not a characteristic.
14. Based on Ritland’s 1991 experiment with Queen and Viceroy butterflies, we now understand
that these butterflies are an example of:
a. Mimicry- but there is not enough information to distinguish the exact type of mimicry.
*b. Müllerian mimicry
c. Batesian mimicry
d. Facultative mutualism
e. Obligate mutualism
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The figure below represents one of the potential scenarios of the competition model. Base your
answers to Questions 15 and 16 on the figure below:
N1
15. Imagine that you are a biologist, and you sample the population sizes of two known
competitors. The point at which their populations intersect is market with a star. Based on the
model, what do you predict will happen to the populations of both species?
i. Species 1 will increase
iv. Species 2 will increase
ii. Species 1 will decrease
v. Species 2 will decrease
iii. Species 1 will remain the same
vi. Species 2 will remain the same
a. i and iv
b. ii and v
c. iii and iv
*d. ii and iv
e. i and v
16. Which of the following statements is true?
a. Species 1 will outcompete Species 2
b. Species 2 will outcompete Species 1
*c. Species 1 and 2 will coexist
d. both species will go extinct
e. We need more information.
17. Which of the following is TRUE regarding the SIR model?
a. As the percentage of infected individuals increases, the percentage recovered individuals
decreases.
*b. As the percentage of infected individuals increases, the percentage susceptible individuals
decreases.
c. As the percentage of recovered individuals increases, the percentage susceptible individuals
increases.
d. The percentage of infected individuals is highest when the percentage of susceptible
individuals is zero.
e. More than one of the above is correct.
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18. Which of the following about a species’ zero population growth isocline (based on the
competition model) is TRUE?
a. The population growth rate is zero ONLY where the isocline crosses the x-axis.
b. The population growth rate is zero ONLY where the isocline crosses the y-axis.
c. The population growth rate is zero ONLY after the isocline levels off at the carrying capacity.
*d. The population growth rate is zero at every point alone the isocline.
e. The population growth rate never reaches zero
19. An invasive species biologist is interested in the potential distribution of a newly introduced
apple snail across the eastern United States. We know that in its native range, the snail is found
in areas that have high annual rainfall, temperatures that rarely go below freezing, mainly cloudy
conditions with high humidity. With these parameters, the biologist uses (the)
_________________ to predict the future geographic range of the introduced snail.
a. index of dispersion test
b. index of dispersal test
*c. ecological niche modeling
d. n-dimensional hypervolume
e. competition model
20. Which of the following variables represents the initial exponential growth stage as expressed
in the logistic growth equation?
a. N/K
b. 1 - (N/K)
*c. rN
d. dN/dt
e. None of the above.
21. Which of the following is not an adaptation for catching prey?
a. Utilization of a search image
b. Larger brain
c. Speed
*d. Unpalatability
e. All of the above are adaptations for catching prey.
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Answer Questions 22-23 based on the following information:
Monica is a conservation biologist interested in preserving species of Polylepis, a genus with
species that are endemic to the high-elevations of the tropical Andes. After collecting abundance
data within the forest, Monica analyzed her data to interpret dispersion patterns for three species.
She concluded that:
Polylepis rugulosa had a dispersion index of 0.45
Polylepis canoi had a dispersion index of 0.999999
Polylepis tomentella had a dispersion index of 1.83
22. Which of the following species has an aggregate (clumped) dispersion pattern?
a. Polylepis rugulosa
b. Polylepis canoi
*c. Polylepis tomentella
d. More than one of the above.
e. None of the above.
23. Which species has a uniform (regular) pattern across the forest landscape?
*a. Polylepis rugulosa
b. Polylepis canoi
c. Polylepis tomentella
d. More than one of the above.
e. None of the above.
24. Two extremely similar species of songbirds coexist in the pothole prairies of Wisconsin.
Both species are territorial, rely on wetlands for nesting sites, and consume certain insects and
seeds as their main food sources. However, Species A nests in shrubs along the edges of
wetlands, while Species B prefers to nest in tall hummocks within the wetland itself. This
evolutionary change in preferred nesting sites, called ____________, leads to ____________.
*a. resource partitioning, niche differentiation
b. resource partitioning, n-dimensional hypervolume
c. evolutionary arms race, niche differentiation
d. evolutionary arms race, n-dimensional hypervolume
e. None of the above.
25. Batesian mimicry is characterized by:
a. two harmful species that resemble each other
*b. two species that look alike but only one is harmful
c. commensal interactions
d. competitive interactions
e. None of the above.
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Answer Questions 26-27 based on the following graph:
C
B
A
26. At which point on the graphical logistic growth model do we see the fastest growth rate?
a. Point A
*b. Point B
c. Point C
d. Points A and C
e. Points A and B
27. At which point do we see the slowest growth rate?
a. Point A
b. Point B
*c. Point C
d. Points A and C
e. Points A and B
28. The major reason that the original mimicry study using Queen and Viceroy butterflies was
flawed is because the scientists only presented birds with Queen butterflies first, then viceroys.
Dr. Ritland and his team improved upon this study by designing a:
a. mathematical model
*b. reciprocal experiment
c. natural experiment
d. chemical analysis
e. None of the above.
QUESTION ELIMINATED – EVERYONE RECEIVES FULL CREDIT
29. In the evolutionary arms race between bats and moths, which of the following was NOT
a moth response to evolving bat predation?
a. diving as a bat approached
*b. distasteful chemicals
c. colorful warning patterns
d. large ears
e. All of the above are adaptations of moths to avoid bat predation.
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30. Parasitism and herbivory are often distinguished from predation because:
*a. Predation involves the killing of prey.
b. Predation has only evolved once, while parasitism and herbivory have evolved numerous
times.
c. The hosts/plants involved in parasitism and herbivory do not sustain a cost because they do not
die.
d. A and B
e. All of the above.
31. Which of the following is NOT an example of a behavioral prey defense?
a. A zebra kicking a cheetah away.
*b. A distasteful newt.
c. A social herd of elephants protecting their young.
d. A deer running from a mountain lion.
e. All of the above are examples of behavioral prey defenses.
32. The California newt produces high levels of the neurotoxin tetrodoxin in the presence of
predators, compared to lower levels in newts that are not under predation pressure. These newts
are also called the "orange bellied" newts, as the lower half of the newt is bright orange, perhaps
as a warning to potential predators. This is an example of:
*a. Aposematism
b. Crypsis
c. Batesian Mimicry
d. Müllerian Mimicry
e. More than one of the above is correct.
33. Based on an adaptation of the competition model, which of the following statements is true
regarding the invasive tick Rhipicephalus (Boophilus) microplus?
a. Bo. microplus does not compete with Bo. decoloratus.
*b. Both species exhibit a decrease in population density in zones where they overlap in range.
c. Bo. decoloratus will likely outcompete Bo. microplus.
*d. Bo. microplus will likely outcompete Bo. decoloratus.
e. Bo. decoloratus and Bo. microplus will likely coexist with similar population sizes.
34. The variable K1/α represents:
a. Intraspecific competition for Species 1
b. Intraspecific competition for Species 2
*c. Interspecific competition
d. Isocline of zero growth
e. None of the above.
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35. Which one of the following is NOT an important characteristic of population distributions?
a. Geographic range
b. Dispersal
c. Density
d. Dispersion
*e. None of the above- these are all important characteristics of population distributions.
36. Which of the following processes does NOT define the demography (the size and structure)
of a population?
a. births
b. deaths
c. immigration
d. emigration
*e. all of the above can determine the demography of a population.
37. Which of the following is NOT an assumption of the exponential growth model?
a. Unlimited resources
b. Unlimited space
c. Negligible immigration and emigration.
*d. Birth rates must equal death rates
e. More than one of the above is NOT an assumption of the model.
38. Which of the following is NOT an example of herbivory?
a. A deer eating several species of grasses.
b. A giraffe eating leaves off of an acacia tree.
c. A chipmunk eating acorns falling from oak trees.
d. An elk eating the flowers off of a scarlet gilia.
*e. All of the above are examples of herbivory.
39. Which of the following statements regarding plant production of caffeine is TRUE?
a. Caffeine a compound produced only by the coffee tree.
*b. Caffeine is a chemical alkaloid produced to reduce herbivory.
c. Caffeine is a distasteful chemical for large herbivores.
d. A and B only.
e. All of the above.
40. Studies have shown that some plants produce chemical defenses in response to herbivory.
This is an example of an:
*a. induced plant defense.
b. induced plant offense.
c. induced response to parasitoids.
d. induced response to pollinators.
e. None of the above.
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41. In terms of herbivory, which of the following is an example of overcompensation?
a. Morphine is a chemical alkaloid produced to reduce herbivory
b. Cottonwood trees producing higher concentrations of salicortin after herbivory
c. Corn leaves releasing volatile chemicals to attract parasitoid wasps after herbivory.
*d. Rose bushes producing more flowers after herbivory than they did before herbivory.
e. Boxwood shrubs producing more stems after herbivory.
42. In the example of overcompensation of the Scarlet Gilia, which of the following was NOT a
major result from their study?
a. Flowering later could reduce seed predation from fly larvae.
b. The plants in the unbrowsed (control) treatment produced the highest amount of flowers of all
the treatments.
*c. Plants in the clipped treatment produced more flowers than those in the browsed treatment.
d. Browsing delayed peak flower production.
e. All of the above were major results from the study.
43. Which of the following statements about Cordyceps (the “Killer Fungi”) is TRUE?
a. Ants infected with the fungal infection crawl up into the canopy.
b. The fungi only infect ants that are already high in the canopy.
c. Forcing their host to climb allows the fungal spores to disperse over a greater area then from
the forest floor.
*d. A and C
e. B and C
44. Which of the following statements is TRUE regarding the chigger parasite?
a. Chiggers are ectoparasites that feed on their host’s blood
b. Chiggers have a complicated lifecycle because they require two hosts to complete their
reproductive cycle.
c. Chiggers are endoparasites that feed on the digested skin tissue of their host.
d. Chiggers are parasites but do not spread any diseases to their hosts.
*e. None of the above are correct.
45. It is important to understand the lifecycle of parasites and the role their host(s) play within
that lifecycle. Which of the following statements is FALSE regarding the general ecology and
life cycle of the malaria parasite?
*a. Malaria is caused by the mosquito- an endoparasite that attacks the liver.
b. The protozoan that cases malaria requires two hosts: one to transport the parasite, and another
to complete its reproductive cycle.
c. The protozoan destroys red blood cells during sexual reproduction.
d. The liver is the location for the asexual cycle of the parasite.
e. A and D are both false.
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46. The competition model is modified from the logistic growth model by adding one major
variable- the competition coefficient. Which of the following statements accurately describes the
biological meaning of alpha and beta?
a. The competition coefficients convert between the number of individuals of one species and the
number of individuals of the other species.
b. The competition coefficients represent the effects of intraspecific competition.
c. The competition coefficients represent the effects of interspecific competition.
d. A and B only
*e. A and C only
47. In class, we discussed using the SIR model to understand the COVID-19 epidemic. Based on
this modified model, adding parameters that simulated a quarantine _________
a. extended the overall duration of infectivity.
b. caused a delay in the time it took to reach the peak number of infections.
c. resulted in the susceptible population’s crash to decline faster.
*d. A and B only
e. did not alter the predictions from the original model.
48. Recall our discussion of using the SIR model to understand the COVID-19 epidemic. What
factor(s) is/are missing from the basic SIR model?
a. Deaths in the population
b. Variation in immunity and infectivity within the population
c. New variants caused by mutations of the infectious disease
d. A and C only
*e. All of the above are missing from the basic SIR model.
49. In the beginning of the semester, we learned about induced responses to predators. Which of
the following is an example of an induced response from this unit’s lectures?
a. Viceroy and Queen butterflies producing distasteful chemicals
b. Herbivores, like giraffes and elephants, growing into large adults
*c. Cottonwood trees producing higher concentrations of salicortin after herbivory
d. Cacti producing spines in the hottest climates
e. All of the above are induced responses.
50. We spent a significant amount of time discussing the evolutionary pressures of intra- and
interspecific competition. Which of the following statements in true?
*a. The competition models predict that stable coexistence only occurs when interspecific
competition is weaker than intraspecific competition.
b. The competition models predict that stable coexistence only occurs when intraspecific
competition is weaker than interspecific competition.
c. The competition models predict that stable coexistence only occurs when intraspecific
competition is equal to interspecific competition.
d. The competition model concludes that stable coexistence can never occur.
e. More than one of these statements is true.
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