This document appears to be an exam for a grade 11 humanities class on ecosystems and environmental science. It contains 4 sections with multiple choice and short answer questions. Section 1 asks students to name and describe an ecosystem, identify abiotic factors, and evaluate methods to measure biotic factors. It also asks students to calculate Simpson's diversity index for two forest areas and explain the difference. Section 2 distinguishes between predators and parasites and asks students to identify a food chain diagram and explain why there are often more organisms at the third trophic level. Section 3 provides a food web diagram of the North Sea ecosystem and asks students to identify trophic levels and explain limits to the number of trophic levels. Section 4 examines a food chain exposed

1. GURU CHARAN KUMAR/IB ESS 2012
HUMANITIES DEPARTMENT
ESS GRADE 11 SUMMATIVE-OCTOBER 2012
TIME: 1 HOUR
MARKS: 45
1)
(a) (i)
Name and briefly describe an ecosystem you have studied.
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(1)
(ii)
State two abiotic factors significant in the ecosystem.
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(2)
(iii)
Outline and evaluate a method to measure one of the selected biotic factors.
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(3)
(b)
Name an organism found in the ecosystem specified above. Describe and evaluate a
method for estimating its abundance.
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Page 1 of 8

2. GURU CHARAN KUMAR/IB ESS 2012
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(4)
Two areas of forest each contain 50 trees. The species composition of the two areas is as follows.
Area A
Eucalyptus
42
25
Casurina
(c)
Area B
8
25
Simpson’s diversity index can be calculated by applying the formula below,
D=
where:
N ( N 1)
n( n 1)
N = total number of organisms of all species,
n = number of organisms of a particular species.
(i)
Calculate Simpson’s diversity index for area B (showing your working).
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(3)
(ii)
Simpson’s diversity index for area A is 1.38. Suggest a reason for the difference
between the values for these two areas.
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(1)
Page 2 of 8

3. GURU CHARAN KUMAR/IB ESS 2012
iii) With the help of a diagram, state what is meant by the term food-chain.
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( 2 marks)
(Total 16 marks)
2)
(a)
Distinguish between the terms predator and parasite.
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(2)
80 parasites
10 herbivores
100 producers
(b)
(i)
State the name of the type of diagram shown above.
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(1)
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4. GURU CHARAN KUMAR/IB ESS 2012
(ii)
Suggest why there are often more organisms at the third trophic level than at the
second trophic level in a food chain containing parasites.
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(2)
(c)
Explain why the energy available to the predators in a food chain is much less than that
fixed by the producers.
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(4)
(Total 9 marks)
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5. GURU CHARAN KUMAR/IB ESS 2012
3) Figure 1 shows a simplified food web for the North Sea in Europe.
Figure 1
Insolation
from sun
(solar energy)
Surface of sea
Euphotic zone
(light available for
photosynthesis)
Mineral
nutrients
in solution
Seabirds ( e.g. puffin, gannet)
Seals
Phytoplankton
Zooplankton
Mackerel
Jellyfish - - - - - - - - - - - - -Sand-eels- - - - - - - - ----------------------------------------- -Carbon dioxide
dissolved in
seawater
Herring
Dolphins
Squid
Demersal fish ( e.g. cod, haddock)
Crustaceans
( e.g. crabs, lobsters)
Continental shelf
Benthic zone
(sea bed)
Detritus (decaying
organic material)
SEDIMENT
[Adrian Kidd, Managing Ecosystems, (Hodder & Stoughton, 1999) p. 41; p. 72. © Hodder and Stoughton.
Reproduced by permission of Hodder & Stoughton Ltd.]
(a)
(i)
Complete the table below by assigning each of the following types of organisms
from Figure 1 to its correct trophic level.
jellyfish, crustaceans, dolphins, zooplankton, puffins, phytoplankton
Producer
Primary
Consumer
Secondary
Consumer
Tertiary
Consumer
Decomposer
(3)
(ii)
Explain why there is a limit to the number of trophic levels which can be supported
in an ecosystem.
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Page 5 of 8

6. GURU CHARAN KUMAR/IB ESS 2012
(3)
(iii)
In the 1970s sand eels were harvested and used as animal feed, for fishmeal and for
oil and food on salmon farms. State and explain what impacts a dramatic reduction in
the number of sand eels might have on the rest of the ecosystem.
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(4)
(Total 10 marks)
Page 6 of 8

7. GURU CHARAN KUMAR/IB ESS 2012
4) The figure below shows a simple aquatic food chain which has been exposed to a pesticide called
DDT.
Land progressive sequence
Milk
Meat
Aquatic progressive sequence
Humans, the
ultimate accumulators
Third carnivore
(larger fsh)
Second carnivore
(larger fsh)
Grazing
animals
First carnivore
(larger fsh)
Herbivore
(smaller fsh)
First accumulator
(algae, water plants)
Grass
Pollutant in
molecular form
DDT
spray
[Source: Adapted from Goudie, A (1993) The Human Impact on the Natural Environment, Blackwell, p.219]
(a)
(i)
State how many trophic levels are shown in the figure above.
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(1)
(ii)
Identify which trophic level represents:
the producers .....................................................................................................
the top carnivores ..............................................................................................
(1)
(iii)
State and explain what may be happening to the concentration of pesticide in the
food chain.
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(2)
Page 7 of 8

8. GURU CHARAN KUMAR/IB ESS 2012
(b)
An estimated 1000 kg of plant plankton are needed to produce 100 kg of animal plankton.
The animal plankton is in turn consumed by 10 kg of fish, the amount needed by a person
to gain 1 kg of body mass.
(i)
Explain why the amount of biomass declines at each successive trophic level.
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(3)
(ii)
Distinguish between a pyramid of biomass and a pyramid of productivity.
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(3)
(Total 10 marks)
Page 8 of 8