Download Name: Section A: Multiple-Choice Questions *SELECT THE MOST

STAGE 2 BIOLOGY
FORMATIVE SACE TEST
HERITAGE COLLEGE
A CHRISTADELPHIAN SCHOOL
ADELAIDE, AUSTRALIA
TOPIC: ECOSYSTEMS
Name: ____________________________
Section A: Multiple-Choice Questions *SELECT THE MOST CORRECT ANSWER*
1. Which of the following best defines an ecosystem?
J Interactions of organisms with each other and with the physical environment.
K Portion of the surface of the earth where living things exist.
L A community and its physical environment.
M Members of the same species that inhabit a particular area.
2. Examine the table below, which reveals the concentration of a pesticide toxin in the tissue of four
different organisms. All four organisms are related in a food chain. Which one of the following would
most likely be the Wedge-Tailed Eagle?
Organism
Concentration of Toxin
(parts per million)
0.005
0.067
2.34
17.0
J
K
L
M
3. Various types of organisms, including native grasses, bushes, insects, small birds, and small reptiles
live in the field across the road from Heritage College. These organisms together make up
J a community
K an ecosystem
L a population
M a habitat
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4. The following statement best describes energy in relation to a community:
J more energy is made use of in a community, than is wasted
K more energy flows through a community, than is captured in living mass
L more energy is captured in a community, than is lost
M more energy is stored and available as you move up trophic levels in a community
5. Which statement would be most correct in regard to productivity of an ecosystem?
J it will be lowest where there are high levels of phosphates and nitrates
K it will be lowest where there is more rain than sunlight
L it will be highest at lower levels in aquatic environments
M it will be highest at the equatorial regions of the earth
6. After the Black Saturday bushfires that ravaged Salt Creek in Victoria in 2009, there has been a slow
but steady re-establishment of grasses and bushes. This can best be described as
J Primary Succession
K Secondary Succession
L Tertiary Succession
M Natural Selection
7. The wounds of patients who have undergone surgery are susceptible to bacterial infections.
Methicillin and other antibiotics are often used to treat infections of surgical wounds, but do not
always cure them. Which one of the following statements about the development of resistance to
antibiotics in bacteria such as Enterococcus faecium is correct?
J Individual bacteria that are not affected by antibiotics evolve resistance.
K Bacteria that are exposed to methicillin will become resistant to all antibiotics to which they are
exposed.
L A number of individuals in a population of bacteria may be resistant to methicillin.
M A person who is resistant to methicillin will pass on the methicillin-resistant gene to the bacteria.
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8. Refer to the following diagram, which shows a pyramid of numbers in typical savanna woodland.
2nd order consumers
1st order consumers
producers
The number of producers is smaller than the number of 1st order consumers, but the community
of organisms is still sustainable. Which of the following statements is most likely to be true:
J the producers will still have a greater biomass than the 1st order consumers
K the producers are able to pass on a very high degree of energy to the 1 st order consumers
L the 1st order consumers don’t need much energy to survive
M the 2nd order consumers are keeping the producer numbers down
9. Which of the following statements best describes a possible fate of a carbon atom taken up by a
plant in photosynthesis?
J Released back into the atmosphere as part of an oxygen molecule
K Releases back into the atmosphere as part of a carbon dioxide molecule
L Broken down to be used for energy
M Combined into a glucose molecule
10. Which one of the following statements about natural selection is incorrect?
Natural selection may
J result in an increase in the percentage of well-adapted individuals in a population
K cause new genes to appear in a gene pool
L result in an increase in the frequency of favorable genes in a gene pool
M occur in stable environmental conditions
11. A population of rare plants has been segregated into two separate populations by the introduction of
a new hydroelectric project. Which statement best describes the situation?
J Speciation has occurred.
K Natural selection will exert the same pressures on both populations.
L Geographic isolation may lead to reproductive isolation.
M The gene pool will remain identical between the two populations.
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12. The main contributing factor leading many species towards endangerment or extinction is:
J Our interruption of the carbon cycle.
K Our destruction of habitat.
L Our increasing human population.
M Our contamination of water resources.
13. Refer to the following graphs, which show the distribution of fang length in two populations, A and B,
of adult female wolf spiders that live in different environments. The dotted line indicates the
optimum fang length for capturing the most common prey in each environment.
Which of the following statements is consistent with the information shown in the graphs?
J The average fang length in population A is greater than the average fang length in population B.
K The environment of population A has a wider range of prey than the environment of population B.
L The number of individuals in population A is the same as that in population B.
M Population A would be more likely than population B to become extinct if the average size of prey
in both environments decreased.
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14. Refer to the following graph, which shows the distribution of huntsman spiders at a forest boundary:
One species of huntsman (Isopeda isopedella) varies in body colour from dark brown to light grey. In
one community at the forest boundary, two populations of this species were found. Some were
found living in the leaf litter inside the forest and others were found living in the grass just outside
the forest. The relative numbers of dark brown adult spiders and light grey adult spiders found at
certain distances from the forest boundary are shown in the graph above.
The best explanation for this distribution is that
J the two populations of spiders were once different species.
K the two populations of spiders were unable to interbreed and individuals were adapting to suit
their habitats.
L the differences in the two habitats had changed the physical appearance of the individual spiders.
M a particular body colour provided a selective advantage to spiders in a particular habitat.
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Section B: Short Answer
1. Refer to the following diagrams, which show the appearance of three species of flowering plants
called giant Senecios at different altitudes on a mountain.
There are eleven species of giant Senecios. All grow on the slopes of high, isolated mountains in east
Africa. No more than three species are found on any one mountain, and different species occur at
different altitudes on a mountain.
(a) State one biotic factor and one abiotic factor that could determine the distribution of giant Senecios.
______________________________________________________________________________________
______________________________________________________________________________________
(2)
(b) A study of the DNA of giant Senecios showed that each species had its closest relative on the same
mountain
State why the examination of DNA is used to study evolutionary relationships (according to the
theory).
______________________________________________________________________________________
______________________________________________________________________________________
(2)
(c) State one mechanism that may prevent interbreeding among different species of giant Senecios on
the same mountain.
______________________________________________________________________________________
______________________________________________________________________________________
(2)
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2. Refer to the following table, which shows soil characteristics from undisturbed sections of the Pasoh
Forest and from logged sections of the Pasoh Forest. The Pasoh Forest is a rainforest in the central
lowland area of Malaysia.
Soil characteristics
Moisture content (%)
Organic carbon (%)
Total nitrogen (%)
Soils from undisturbed sections
28.80
2.70
0.23
Soils from logged sections
19.70
1.27
0.07
(a) Use one piece of evidence from the table to support the idea that there are more decomposers in
the soils from the undisturbed sections than in the soils from logged sections of the Pasoh Forest.
Explain.
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
(4)
(b) The Malaysian National Forestry Policy, which aims to achieve sustainable forestry, suggests that
only rainforest trees with diameters over 500mm should be harvested. This policy is in contrast to
the practice of clearing large areas of rainforest and then replanting these cleared areas with a single
introduced species such as the rubber tree.
Explain why there is less impact on the rainforest community from selectively harvesting large trees
than from clearing large areas of rainforest and then replanting these with a single introduced
species.
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
(4)
3. In the space below clearly outline three main differences between r-selected and k-selected
reproductive strategies. Use a simple graph to aid in your answer.
(6)
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4. In 1965 a survey of the herbivorous Espanola tortoise population in the Galapagos Islands showed
that the numbers of the Espanola tortoises had declined to fourteen individuals. Conservationists
transferred the fourteen Espanola tortoises to a research station where the tortoises successfully
reproduced. In 1975 the Espanola tortoises were released from the research station. The population
in the Galapagos Islands now numbers between 800 and 1000.
(a) State one human activity that could have led to the decline of the original Espanola tortoise
population.
______________________________________________________________________________________
______________________________________________________________________________________
(2)
(b) The genetic variability in the gene pool of the current Espanola tortoise population is very low.
i) Define the term ‘gene pool’.
_______________________________________________________________________________
_______________________________________________________________________________
(2)
ii) Explain why low genetic variability in the gene pool of the tortoise population could affect the
survival of the species in the future.
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________
(4)
(c) State one consequence that the decline of the Espanola tortoise population could have for the
ecosystem of the Galapagos Islands.
______________________________________________________________________________________
______________________________________________________________________________________
(2)
5. Give two possible examples for each of the following types of reproductive isolation:
(a) Pre-zygotic:
(2)
(b) Post-zygotic:
(2)
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6. State the definition of net primary productivity, and include a set of units used to measure it:
______________________________________________________________________________________
(2)
Section C: Extended Response
Write your answer on the answer sheet provided. You should spend about 12-15 minutes on this section,
about 3-5 minutes planning and 9-10 minutes writing. An ‘A’ level performance will show a clear, wellexpressed answer that is well organised, relevant to the question, and demonstrates a deep and broad
level of understanding.
1. After a large bushfire there are significant changes in the number and type of plant species in the
area. In one study, sixty-three plant species were recorded in one area a year after a bushfire,
compared with only ten plant species recorded in the area before the bushfire.
 Explain why many different plant species were able to establish in the area in the first year after
the fire.
 Describe how succession occurred in this plant community after the first year.
 Explain why biodiversity is considered to be a desirable feature of a biological community, and of
our earth overall.
(15)
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Extended Response Answer Sheet
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