Topic 4 Practice Questions Marking Scheme
(a)
(i)
(b)
Northern Andes
1
(ii)
Amazon Basin
1
(iii)
Overall figures are high [1]/high productivity [1].../... and
structural complexity of tropical ecosystems [1];
Northern Andes high biodiversity due to genetic isolation on
mountain summits and in remote valleys [1]/range of
environments due to altitudinal variation [1]/Amazon Basin
a relatively homogeneous environment [1];
Any reasonable alternative. [Must have something more than
‘tropical forest ecosystems are complex’ for both marks.]
2
A species of organism, of which numbers are so low that there
is a likelihood of its becoming extinct in the near future/owtte [1];
named species [1];
[IUCN definition = taxa in danger of extinction and whose
survival is unlikely if causal factors continue operating.
Includes taxa with numbers at a critical level; those with
drastically reduced habitats; and those not seen in the wild in
the past 50 years.]
2
Any three of: small numbers [1]/restricted distribution [1]/
complex migration patterns [1]/complex breeding cycle [1]/
reduced habitat [1]/low rate of reproduction [1]/hunting
pressure [1]/economic value [1]/or reasonable alternatives.
3
(i)
(ii)
(c)
(d)
Any 3 ways with examples [1] each, e.g.
Protective legislation (koala in Australia in early 20th century) [1];
International treaty (CITES) (Green Amazon parrots) [1];
Breeding programmes (numbats in Australia/pandas) [1]/protection
of habitats (whooping crane in USA) [1];
Any reasonable alternative
(2 ways, but no examples = [1])
3
Natural selection = a mechanism of evolution [1]/caused by removal
of ill-adapted individuals and survival of those adapted to the
environment [1]; evolution in long term → biodiversity by filling
available niches [1]; isolation (cutting off islands/formation of
mountains etc.) separates populations [1]/changing environment
may create isolated populations [1]/climatic change may trigger
adaptation to new conditions [1].
3
[15]
(a)
describe:
very low numbers of extinctions before 1650;
slightly higher number 1651 to 1850/approximately 0.5 species
per year;
(b)
(c)
(d)
rapid increase 1851 to 1950/approximately 2.5 per year;
decrease in extinction rate since 1951 to approximately one
species per annum;
2 max
explain:
extinction rate before 1850 low as human effect on biodiversity low
as population pressure on environment relatively low;
extinctions before 1850 not fully recorded;
extinction rate 1851 to 1950 much higher due to rapid human
population increase;
and rapid rate of habitat loss;
decrease in extinction rate since 1951 due to greater efforts to
protect endangered species and ecosystems;
or many vulnerable species already extinct;
any other reasonable points;
3 max
low total numbers/long or complex migration route/specialised
habitat/specialised food sources/widely hunted or otherwise
used by humans/low reproduction rate/large number of
predators/susceptibility to disease/limited distribution/
catastrophe such as flooding or meteor impact;
any other reasonable points;
Responses need two factors per mark.
Factors must be specific to extinction of organisms. No credit for
vague answers such as “global warming” or “degradation of
environment”.
2 max
endangered:
species in danger of becoming extinct in the immediate future
because their numbers have declined to a critical level;
extinct:
species believed to no longer exist alive;
2 max
Any reasonable example: reasons must be appropriate to example.
[1] for name and [2] for reasons e.g.
name: Dodo;
reasons: confined to small island (Mauritius);
extreme tameness;
hunting as a source of food by visiting sailors;
destruction of forest habitats;
competition with introduced organisms, e.g. pigs;
3 max
Note: recent research has suggested that dodos were not very tame
and that the flesh was unpleasant to taste; thus habitat
destruction and introduction of pigs (and rats) were
probably most significant factors. However, the points
given above are widely mentioned in the literature and
may be considered acceptable responses.
(e)
(i)
[1] for name, [1] for brief description e.g.
Kakadu National Park, Northern Territory, Australia;
tropical savanna with extensive wetlands;
2 max
(ii)
(f)
Any reasonable examples, but must have some evaluation
for full [5] marks.
For above example:
measures:
designation as World Heritage Area by UNESCO;
involvement of Aboriginal people in management;
concentration of visitor pressure, campsites, into limited areas;
strict protection of flora and fauna by law;
international agreements with Japan, China to protect migratory
birds;
attempts to eliminate introduced species;
3 max
evaluation:
considerable success, as measured by visitor numbers;
and protection of habitats and biodiversity;
success due to use of modern scientific techniques and
traditional land management;
and due to use of local, national and international measures;
2 max
genetic diversity represents the variety of genetic material in a gene
pool or population, habitat diversity is the range of different habitats
or ecological niches in an ecosystem, community or biome/OWTTE
1 max
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