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ECO701S - ECOLOGY - 2ND OPP - JULY 2022 |
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NAMIBIA UNIVERSITY
OF SCIENCE AND TECHNOLOGY
FACULTY OF HEALTH, APPLIED SCIENCES AND RESOURCES SCIENCES
DEPARTMENT OF NATURAL AND APPLIED SCIENCES
QUALIFICATION : BACHELOR OF SCIENCE
QUALIFICATION CODE: 07BOSC
COURSE: ECOLOGY
LEVEL: 7
COURSE CODE: ECO701S
DATE: JULY 2022
DURATION: 3 HOURS
SESSION: 2"¢ OPPORTUNITY
MARKS: 100
EXAMINER (S)
MODERATOR
SECOND
OPPORTUNITY EXAMINATION
Dr Norman Muzhinji
Prof Isaac Mapaure
QUESTION
PAPER
INSTRUCTIONS
All examination RULES apply
Answer ALL questions in the spaces provided
Read all the questions carefully before answering
Marks are indicated at the end of each question
Write clearly and neatly.
All written work MUST be done in BLUE or BLACK ink.
PERMISSIBLE MATERIALS
Non-programmable calculators
ATTACHMENTS
None
THIS QUESTION PAPER CONSISTS OF EIGHT (8) PAGES
(INCLUDING THIS FRONT PAGE)
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Section A: Multiple choice questions (20 marks)
The primary stages of the nitrogen cycle are (starting with atmospheric N2):
A. Ammonification, denitrification, nitrogen fixation, nitrification, assimilation
B. Nitrogen fixation, anmonification, assimilation, nitrification, phosphorylation
C. Nitrogen fixation, nitrification, assimilation, respiration, ammonification
D. Nitrogen fixation, nitrification, assimilation, ammonification, denitrification
Which of the following best describes a relationship in which two species both
mutually benefit from each other’s behaviors?
A. Competition
B. Parasitism
C. Commensalism
D. Mutualism
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
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.
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.
In a logistic growth curve, exponential growth is the phase in which the population
A. Reaches carrying capacity.
B. Grows quickly.
C. Growth begins to slow down.
D. Growth stops.
No two species are able to occupy the same niche in the same habitat at the same
time?
A. Because of the interactions that shape the ecosystem.
B. Unless the species require different abiotic factors.
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C. Because of the competitive exclusion principle.
D. Unless the species require different biotic factors.
8. The law of Physics stating “some energy will be lost as heat in any conversion
process” is readily applied in ecosystem ecology to understand
Energy transfer efficiency across trophic levels.
The absorption of sun light by primary producers.
The cycles of chemical elements.
The effect of consumers on producers
Ideally, sustainable development should
A. Put the protection of the environment ahead of human needs.
B. Provide for human needs at the expense of the environment.
C. Use more natural resources to make goods to meet human needs.
D. Preserve ecosystems while providing for human needs.
10. A species that exerts a strong control on community structure by having the highest
abundance or biomass in a community is a,
A. Keystone
B. Dominant
C. Predator
D. Mutualistic
11. One of the impacts associated with the current increase in COzin the atmosphere is
A. An increase in the greenhouse effect leading to higher average global
temperatures.
B. A higher proportion of skin cancers and cataracts in humans.
C. An increase in nutrient concentration across terrestrial water systems.
D. A decrease in global temperatures
12. The total amount of living tissue within a given trophic level is called the
A. Organic mass.
B. Trophic mass.
C. Energy mass.
D. Biomass
13. Only 10 percent of the energy stored in an organism can be passed on to the next
trophic level. Of the remaining energy, some is used for the organism’s life processes,
and the rest is,
A. Used in reproduction.
B. Stored as body tissue.
C. Stored as fat.
D. Eliminated as heat
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14. A population of bats exhibits logistic growth. If the carrying capacity is 500 butterflies
and r = 0.1 individuals/(individuals/month), what is the maximum population growth
rate for the population?
(Hint: maximum population growth rate occurs when N = K/2).
A. 12.5 individuals/ month
B. 10 individ/uamolnsth
C. 5 individuals/ month
D. 7.5 individuals/moth
15. Excessive nitrate levels are often found in the groundwater of areas with intensive
agriculture.
Which is an agricultural practice that can cause such levels?
A. Improper construction or maintenance of animal waste lagoons
B. Use of ammonia in disinfection of meat products
C. Application of pesticides on fields before harvesting
D. Planting monocultures of GMO legume plants for crops
16. Character displacement:
A. Reduces inter-specific competition through "niche differentiation"
B. Is a co-evolutionary response to inter-specific competition
C. Implies that competing species will differ more in allopatry than in sympatry
D. A and B, but not C, are correct
E. A, B and C are correct
17. An ecologist studying several forest-dwelling, insect eating bird species does not find
any evidence of interspecific competition. The most likely explanation is
A. Lack of keystone species
B. Low species richness
C. Pronounced intraspecific competition
D. Resource partitioning
18. In a forest community, a shelf fungus and a slug live on the side of a decaying tree
trunk. The fungus digests and absorbs materials from the tree, while the slug eats
algae growing on the outside of the trunk. These organsims are
The same habitat, but different niches
The same niche, but different habitats
the same niche and the same habitat
different habitats and different niches
19. In the National Botanic Garden of Namibia, there are 50 species more than 25 species
found at the Ombili Conservative Centre. In between them, they have 5 species in
common. Calculate the Sorenson’s coefficient
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A. 0.067
B. 0.13
G5
D. 3
20. Abandoned farms usually reverts to forest after some time. This process of forest
regeneration is called:
A. Primary succession
B. Biorestoration
C. Secondary succession
D. Climax succession
Section B: Answer all questions and use the spaces provided (80 Marks)
1. A fisheries ecologist wishes to optimize her yield by maintaining a population of trout
at exactly 1000 individuals. Predict the initial instantaneous growth rate if the
population is stocked with an additional 700 fish. Assume r_ is 0.008
individuals/(individual* day).
[4]
2. Study the survivorship curves below: Answer each question with Type |, Type II, or
Type Ill as the answer and explain your choice.
01
Age
i.
Which of the survivorship curves in the graph is typically observed in
some lizard species?
[2]
ii.
Characteristic of species that exhibit r-selection strategy in production
of offspring
[2]
iii.
Which of the survivorship curves in the graph is typically observed in
some large mammalian species like elephants?
[2]
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3. In 2021, a researcher studying the population dynamics of monarch butterflies
estimated that the size its population was 7,000. Over two years, he records 980 births
and 120 deaths in that population. Estimate r and calculate what the population size is
predicted to be in 2024 years.
[5]
4. Explain, with examples, how interspecific competition influences species coexistence
and community diversity
[3]
5. 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]
6. How are species diversity and genetic diversity different?
[2]
7. Why are alien invasive species successfully colonise and spread in native new habitats
[2]
8. The figure below shows five islands (A to E) and their distances from the mainland.
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B
Mainland
a. Rank the islands from highest number to lowest number of expected species. Justify
your ranking.
[3]
b. Explain why diversity of species decline as we move away from the equator.
[3]
9. The figure below shows the growth of protozoan species Paramecium caudatum when
grown individually in the laboratory chamber environment.
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80+ P. caudatum alone
2 4 6 8 10 12 14 16 18
Days
a. What is the mean growth rate of P. caudatum from day 2 to 6?
[2]
b. Figure below shows P. caudatum grown together with P. aurelia (mixed culture) in
the same laboratory chamber (habitat). What effect does growing P. aurelia have on
the population growth rate of P. caudatum? What could be an explanation for this?
[2]
P. aurelia | inaS
caudatum ii n
2 4 6 8 10 12 14 16 18
Days
10. Outline the human activities that have changed the global nitrogen cycle. How do
changes in nitrogen cycle affect the carbon cycle?
[4]
11. Suggest three measures that can be implemented to manage loss of biodiversity in a
community with resources managed under "Tragedy of the Commons".
[3]
12. Your friend tells you that a good way to increase biodiversity is by intentionally
introducing a species to a new environment because it will increase species richness of
that area by one species. Do you agree or disagree with your friend’s statement?
Support your answer.
[2]
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13. Describe the changes in biotic factors that are visible in the figure below showing
ecological succession following a fire
[4]
{''
;j
'!i
|'
1''{
''
Time progression
.
é Annual
Ouk
2 Other
Grasses @ plants BB Shrubs Re Irees
~~ trees
2
14. List any five (5) human activities that that leads to loss of biodiversity
[5]
15. One of the goals of Namibia ‘s Ministry of Environment, Forest and Tourism is to draft
a five year strategy (2020-2025) that outlines a path towards a sustainable future for
the environment focusing on four priority areas of climate change and energy,
resources and waste management, water management and urban environment.
Imagine, you have been appointed by the Minister as a consultant to carry out this task,
outline and discuss the strategies that you would propose and present to the Minister
for creating a sustainable environment in Namibia for each priority area.
[2]
16. 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.
[3]
Insect order | Description
Number of | n/N
pi
pi
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