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ECO701S - ECOLOGY - 1ST OPP - JUNE 2023 |
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nAmlBIA UnlVERSITY
OF SCIEnCE Ano TECHn OLOGY
FACULTYOF HEALTH,NATURALRESOURCESAND APPLIEDSCIENCES
DEPARTMENTOF BIOLOGY,CHEMISTRYAND PHYSICS
QUALIFICATION: BACHELOROF SCIENCE
QUALIFICATION CODE:07BOSC
LEVEL: 7
COURSE:ECOLOGY
COURSECODE: ECO701S
DATE: JUNE 2023
SESSION:1st OPPORTURNITY
DURATION: 3 HOURS
MARKS: 100
FIRSTOPPORTUNITYEXAMINATION QUESTION PAPER
EXAMINER: Dr N. Muzhinji
MODERATOR: Prof I. Mapaure
THIS EXAMINATION PAPERCONSISTSOF FIVE (5) PAGES
(INCLUDING THIS FRONT PAGE)
INSTRUCTIONS
1. All examination RULESapply
2. Answer ALLquestions
3. Read all the questions carefully before answering
4. Marks are indicated at the end of each question
5. Write clearly and neatly.
6. All written work MUST be done in BLUEor BLACKink.
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Section A: Multiple choice questions (6 marks)
l. The primary stages of the nitrogen cycle are (starting with atmospheric N2):
A. Ammonification, denitrification, nitrogen fixation, nitrification, assimilation
B. Nitrogen fixation, ammonification, assimilation, nitrification, phosphorylation
C. Nitrogen fixation, nitrification, assimilation, respiration, ammonification
D. Nitrogen fixation, nitrification, assimilation, ammonification, denitrification
2. Which of the following best describes a relationship in which two species both mutually
benefit from each other's behaviours?
A. Competition
B. Parasitism
C. Commensalism
D. Mutualism
3. Which ecological inquiry method is an ecologist using when he or she sets up a greenhouse
and measures the effects of different levels of carbon dioxide on an endangered plant
species?
A. Questioning
B. Experimentation
C. Modelling
D. Forecasting
4. Introduced species can threaten biodiversity because they can
A. Cause desertification.
B. Cause biological magnification.
C. Crowd out native species.
D. Reduce the amount of fertile land.
5. An organism's niche is
A. The range of physical and biological conditions in which an organism lives and the way it
obtains what it needs to survive and reproduce.
B. All the physical and biological factors in the organism's environment.
C. The range of temperatures that the organism needs to survive.
D. A full description of the place an organism lives.
6. Which of the following statements about human population in industrialized countries is
incorrect?
A. Life history is r selected.
B. Average family size is relatively small.
C. The population has undergone the demographic transition.
D. The survivorship curve is Type I
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Section B: Answer all questions (94 Marks)
1. A population of Springboks is split into two habitats by a river. After many years, the river is
filled with sand due to siltation, and the two populations are reunited. However, individuals
are now unable to breed across the different populations. They can only breed with individuals
from their own group. What type of a speciation is this? Explain it in detail.
(4]
2. Both the dominant and keystone species exert strong effects on the character of a community,
but in different ways. How do dominant species and keystone species differ in influencing the
character of the community?
[2]
3. a. Describe the abiotic and biotic characteristics of wetland biome and where it is found in
Namibia.
[6]
b. State any four (4) human threats to the biodiversity of the wetland biome.
[4]
c. As an renowned ecologist/biologist working in the Ministry of Environment, Forestry and
Tourism, what are the strategies that you can implement to preserve the biodiversity in
the wetland biome.
[4]
4. Explain using examples the principle of;
a. lnterspecific competition
[2]
b. Competitive exclusion
[2]
c.
Resource partitioning
[2]
5. Species 1 and Species 2 compete for a common limiting resource. The two-species dynamics
follow the Lotka-Volterra competition model (logistic competition).
Species 1 has carrying capacity Kl= 100;
Species 2 has K2 = 150 with a12= 0.5.
Suppose a21 = 1.5. Analyze the 0-isoclines and predict the outcome of competition. [8]
6. Describe at least four (4) forces of evolution that drive changes in genetic makeup of
population over time.
[4]
7. The graphs below show the trends in (A) wolf population after being introduced into a
national park and the populations of (B) Elk deer(C) cotton wood and (D) Willow trees.
Examine the graphs and use them to answer the following questions below
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a.
What is the best explanation for the change in elk population?
(1}
b.
How can the change in cottonwood abundance be explained?
[1]
c.
If the wolf were to be removed from the national park ecosystem, how would you expect
d.
the population of elk to change.
[1]
8. Giving examples, describe the impact of human activities like mining and agriculture on
terrestrial and aquatic ecosystems.
[6]
9. The table below shows the number of different species of insects on an experimental field.
Complete the table below and compute the Simpson Index (D} as well as Shannon index (H}of
the insects in the field.
[8]
Insect order Description
Number of n/N
pi
pi2
individuals
Wasp
black
6
Wasp
Purple
5
Bee
Stripped
1
Grasshopper Green with red 3
legs
Butterfly
Large blue
12
In pi
pi In pi
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10. Compare and contrast density-dependent growth regulation with density-independent growth
regulation. Give an example of each as they might affect a caterpillar population.
[5]
11. An ecological system is any set of components, living or non-living, that are connected
together by regular interactions. An ecological system can be a single organism and its
surroundings, a population or set of interacting populations in a certain habitat, or the entire
community together with the abiotic environment with which these species interact, a unit
termed an ecosystem. Describe different research methods that ecologists use to study
ecosystems. [12]
12. a. With the aid of diagrams, describe the Phosphorous cycle?
[8]
b. Describe four (4) human activities that interfere with the Phosphorous cycle.
[8]
13. Study the marine food web diagram shown below and answer the following questions.
a.
b.
c.
d.
e.
f.
why?
Name the primary producer
[1]
Name a primary consumer
[1]
Name a secondary consumer
[1]
What effect would a reduction in light have on this food web?
[1]
Explain your answer ind above.
[1]
Which speies would be most negatively impacted by a reduction of phytoplankton and
[1]
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