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ECO701S - ECOLOGY - 1st OPP - JUNE 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: JUNE 2022
DURATION: 3 HOURS
SESSION: 15t OPPORTUNITY
MARKS: 100
EXAMINER (S)
MODERATOR
FIRST 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 FOUR (4) PAGES
(INCLUDING THIS FRONT PAGE)
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1. The Kuiseb River had a large population of various kinds of fish. After farmers in the
area started using nitrogenous fertilizers on their fields, rainwater washed excess
fertilizer into the river. After a few months, the amount of algae in the river increased
greatly, while the local fish community decreased dramatically.
a. What is the term that describes the process where an increase in the availability of
nutrients results in an increase in algae?
[1]
b. Why did the fish population/community decrease?
[2]
c. The presence of algae is a biotic factor influencing the fish population. Name ONE
more biotic and TWO abiotic factors that can influence the fish population. [3]
2. A population of springbok is suddenly separated when a highway is built that splits the
population’s habitat in two. After many years, the highway is abandoned, 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 that, and explain it in detail?
[4]
3. a. Describe any four (4) biotic characteristics and four (4) abiotic characteristics of
woodland and desert biomes found in Namibia.
[8]
b. State at least four (4) threats to the biomes you described in (3a).
[4]
c. Asarenowned ecologist/biologist working in the Department of Environment,
what are the solutions that you can suggest to manage the threats you identified
in (3b).
[4]
4. Define population genetics? Explain why understanding population genetics is
important to an ecologist like you.
[4]
5. With the aid of a well labelled diagrams, differentiate between exponential growth
and logistic growth of populations.
[6]
6. Suppose you were tasked with counting the number of Mopane trees in a small
portion of Bwabwata National Park, which is half an acre in size (one acre = 4000 m?).
Using a square quadrat of 2 m in length and you obtain the numbers shown in the
table below
Quadrat number
1 2 3 4 5 6 7 8 9 10
Mopane Tree count
4
5
2
4
1
5
3
2
5
3
a. Estimate the total number of Mopane trees in a small portion of Bwabwata National
Park mentioned above. Show your working.
[5]
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b. Determine the dispersion pattern of the Mopane trees in the Bwabwata National
Park
[4]
c. List any three assumptions of the method you have used.
[3]
Compare and contrast density-dependent growth regulation
independent growth regulation. Give an example of each as they
caterpillar population.
with
might
density-
affect a
[4]
An ecological system is any set of components, living or non-living, that are tied
together by regular interactions. An ecological system is made up of one or more
organisms (biotic), together with the non-living environment (non-biotic) with which
they interact. Ecological systems exist at several different levels of organization. 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 ecologist uses to study ecosystems,
highlighting the advantages and disadvantages of each method.
[20]
As part of anew development, a concert venue consisting of a stage and open grassy
areas for sitting, and parking areas is constructed in a formerly wooded area.
Predict the consequence on the local plant community that is likely to result during
the preparation and construction of the venue. Justify your prediction.
[4]
To maintain the grassy area, large quantities of water and chemicals are applied
regularly. Predict the effect on the local animal community that might result from
regular use and maintenance of the grassy area. Justify your prediction.
[4]
10. Species 1 and 2 compete; community dynamics follows the Lotka-Volterra
competition equations:
Species 1:
Species 2:
dNz _
N
dt '2 2
Kz ~~ N2 ~~ BN,
Competition coefficients:
Q: the effect an individual of species 2 has on the
population growth of species 1
the effect an individual of species 1 has on the
population growth of species 2
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Q = 12
B= a21
N1 is a density, population for species 1,
R1 is an intrinsic rate of increase (r1> 0),
K1 is a carrying capacity, and aN2 is the competitive effect of an individual of
species 2 on the growth of species 1 (0 < aN2< 1).
Suppose K1 = 1000, K2 = 800, a=0.5, and B = 0.1.
a. If N2=100, what value of N1 falls on the 0-isocline of species 1 (where dN1/dt
=0)?
[5]
b. Suppose two species, S1 and $2 (species 2) compete for a common limiting
resource. The two-species dynamics follows the Lotka-Volterra competition
model (logistic competition). Analyze the O-isoclines and predict the outcome
of the competition when K1 = 150, K2 = 220, K1\\a12 = 70, and K2\\a21 = 400. [5]
11. Deforestation has devastated the balance of carbon on the planet, being the second
leading cause of rising atmospheric CO2 levels behind fossil fuel combustion.
a. Given this information, what MAJOR role do forests play in the carbon cycle? [2]
b. The Nitrogen cycle alone is responsible for an increase in atmospheric
concentrations of greenhouse gases.
i. With the aid of a diagram, describe the Nitrogen cycle
[4]
ii. State at least (4) human activities that interfere with the Nitrogen cycle. [4]