ECOSYSTEM QUESTIONS
1.
The sand shrimp, Crangon septemspinosa, is a member of the community found in a sea-shore ecosystem.
(a)
Give the meaning of:
(i)
community; .......................................................................................................
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(ii)
ecosystem. ........................................................................................................
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(2)
(b)
The contours on the graph represent 0%, 50% and 100% survival for C. septemspinosa in aerated
water over a range of temperatures and salinities (salt content of sea water).
30
50% survival
0%
survival
25
Temperature
/ °C
20
100% survival
15
10
5
0
(i)
5
10
15
20
25
30
Percentage salinity
35
40
45
What are the upper and lower limits of temperature for 100% survival of
C. septemspinosa?
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(1)
(ii)
Other than the factors shown in the graph, name one biotic and one abiotic factor, which might
also limit the survival of C. septemspinosa.
Biotic factor ......................................................................................................
Abiotic factor ....................................................................................................
(2)
(Total 5 marks)
2.
The diagram shows some of the feeding relationships in a food web for a forest.
Sparrowhawk
Fox
Grass
snake
Hedgehog
Frog
Blue tit
Ground
beetle
Spider
Slug
Winter moth,
caterpillars
Wood
mouse
Leaves
(a)
Grey
squirrel
Earthworm
Fruits
and
seeds
Wood boring
beetle
Wood
Name an organism that is both a primary and a secondary consumer in this food web.
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(1)
(b)
Name a group of organisms, not shown in the web, which is needed to recycle nutrients.
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(1)
(c)
Explain how bare ground may, over a long period of time, become forest.
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(3)
(d)
With reference to the food web, explain the effect that deforestation has on the species diversity of an
area.
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(3)
(Total 8 marks)
3.
Hares are small mammals similar to rabbits. The diagram shows how some of the hares found in southern
Africa are classified.
Animalia
Chordata
Mammalia
Lagomorpha
Leporidae
Lepus
Pronolagus
Pronolagus
randensis
Jameson's hare
(a)
(i)
Pronolagus
rupestris
Smith's hare
Pronolagus
crassicaudatus
Natal rock hare
Lepus
capensis
Cape hare
Lepus
saxatilis
Scrub hare
Name the genus to which the scrub hare belongs.
...........................................................................................................................
(1)
(ii)
Name the order to which the Natal rock hare belongs.
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(1)
(b)
The map shows the distribution of three of these species of hare.
Key
Jameson's hare
Smith's hare
Natal rock hare
(i)
What is the evidence from the map that suggests that Smith’s hare and the Natal rock hare are
different species?
...........................................................................................................................
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(1)
(ii)
Suggest what has caused the gene pools of the two populations of Jameson’s hare to differ.
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(2)
(Total 5 marks)
4.
Moose are large herbivorous animals.
(a)
In a study of one population of moose, 72 animals were trapped and marked with ear tags. They were
then released. One month later, fieldworkers examined 120 moose and found that 14 of these had ear
tags.
Use these figures to calculate the size of the moose population. Show your working.
Answer:............................
(2)
(b)
Isle Royale is a large island in Lake Superior. Moose first colonised this island in 1900. At the time
they had no predators on the island. Wolves, which are predators of moose, were introduced to the
island in 1950. The graph shows the moose population from 1900.
Island colonised
by moose
Wolves
introduced
3000
2000
Moose
population
1000
0
1900
(i)
1910
1920
1930
1940
Date
1950
1960
1970
Suggest an explanation for the changes in the moose population before the introduction of the
wolves.
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(2)
(ii)
Describe the effect of introducing wolves on the moose population.
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(1)
(Total 5 marks)
5.
(a)
Explain the meanings of the terms habitat and environment.
(2)
(b)
Sulphur dioxide is an important atmospheric pollutant. Lichens are organisms which may be used as
indicator species to monitor concentrations of sulphur dioxide in the air. The graph shows the results
of a study of the number of species of lichen at different distances along a transect through a city
centre.
Mean annual sulphur dioxide concentration/g m–3
65
90
160
200
170
60
50
40
Number of
species of 30
lichen
20
10
0
20
16
12
8
4
0
4
Distance from city centre/km
Describe and explain the relationship between the number of species of lichen, the distance from the
city centre and the mean annual sulphur dioxide concentration.
(2)
(c)
Another part of the investigation involved studying the diversity of lichens on tree trunks. The results
for one tree trunk are shown in the table.
(i)
The index of diversity can be
calculated from the formula
Index of diversity =
N(N – 1)
n (n – 1)

Species of lichen
Number of individuals
A
12
B
3
C
where N
= total number of
organisms of all species
D
and n
= total number of
organisms of a particular species
Use this formula to calculate the index of diversity for the lichens on this tree trunk.
3
2
(2)
(ii)
Describe and explain how you would expect the index of diversity of lichens on tree trunks to
change as you moved along the transect towards the city centre.
(2)
(Total 12 marks)
6.
(a)
“Set-aside” is the common name given to a European Union policy under which farmers receive a
subsidy for land taken out of cultivation. A study was carried out to investigate how the amount of
time a set-aside field was left uncultivated would affect the species of birds feeding there.
Table 1 shows the number of birds of different species feeding in a field which had been left
uncultivated for one year.
Species
Number of birds of that species
feeding in the field
Greenfinch
12
Goldfinch
8
Wood pigeon
3
Chaffinch
1
Table 1
(i)
Use the formula d =
N(N – 1)
 n(n – 1)
where d = index of diversity
N = total number of organisms of all species
and n = total number of organisms of a particular species
to calculate the index of diversity for the birds feeding in the field. Show your working.
Index of diversity.................................
(2)
(ii)
Explain why it is more useful in a study of this sort to record diversity rather than the number of
species present.
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(2)
Figure 1 is a graph showing the relationship between bird species diversity and plant species diversity in this
study. Figure 2 is a graph showing the relationship between bird species diversity and plant structural
diversity for the same study. Structural diversity refers to the different form of plants such as herbs, shrubs
and trees.
Bird
species
diversity
Bird
species
diversity
Plant species diversity
Plant structural diversity
Figure 1
(b)
Figure 2
Describe briefly how you could obtain the date that would enable you to calculate the diversity index
for the species of plant growing on a set-aside field.
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(3)
(c)
(i)
Describe the relationships shown in Figure 1 and Figure 2.
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(2)
(ii)
Explain why the plant structural diversity would increase with the amount of time the field was
left uncultivated.
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(2)
(iii)
Suggest an explanation for the relationship between bird species diversity and plant structural
diversity shown in Figure 2.
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(2)
(d)
In another study of fields taken out of cultivation, the figures shown in Table 2 were obtained.
Time in years since
cultivation stopped
Value of index of
diversity for bird species
5
2.1
15
3.2
20
5.6
25
4.1
40
4.8
60
9.4
Table 2
Predict what might happen to the bird species diversity in the study summarised in Table 2 over the
next 100 years. Explain how you arrived at your answer.
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(2)
(Total 15 marks)