Questions
Q1.
The photograph shows a lake which has been polluted by excess nutrients.
(i) Complete the sentence by putting a cross (
) in the box next to your answer.
The build-up of nutrients in an aquatic environment is known as
(1)
A decomposing
B eutrophication
C mutualism
D parasitism
(ii) Suggest how farming can lead to a build-up of nutrients in the lake.
(2)
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(iii) State the effects of nitrates on plant growth.
(1)
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Q2.
Energy
Scientists can show the relationships between organisms in a variety of ways.
This food chain shows the energy content at each trophic level.
(a) (i) Calculate the percentage of energy that is transferred from the rabbits to the fox.
(2)
answer =...........................................................................%
(ii) State two ways in which energy can be lost between the trophic levels of the rabbit and the fox.
(2)
1
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2
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(b) Suggest how a farmer rearing chickens could limit energy loss from the chickens.
(2)
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(c) (i) Complete the sentence by putting a cross ( ) in the box next to your answer.
Fleas are parasites that feed on foxes.
Another example of parasites are
(1)
A
B
C
D
cleaner fish
lichens
mistletoe
oxpeckers
(ii) Peas and beans are known as legumes.
They form a mutualistic relationship with the bacteria in their roots.
Explain the importance of this mutualistic relationship to the legumes.
(3)
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Q3.
Environment cycling
(b) The human population is increasing.
Explain how this could change the concentration of carbon dioxide in the atmosphere.
(2)
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(c) Air quality can be monitored using indicator species.
Name an indicator species used to monitor air quality.
(1)
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(d) The overuse of fertilisers can cause eutrophication.
Explain the effects of eutrophication that may lead to the death of aquatic animals.
(3)
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Q4.
Catherine is an environmentalist studying water pollution in the stream shown in the diagram.
She took samples of water from locations A, B and C and recorded the number of freshwater shrimps at
each location on the diagram.
Explain which location in the stream is most polluted.
(2)
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Q1.
Answer
Acceptable
answers
(i)
B - eutrophication
(ii)
Any two from the following:
 (over use of) nitrates / phosphates
fertilisers (1)
 leaching into the lake(1)
 sewage leakage into the lake (1)
(iii)
(plant growth) is
increased / protein is
made(1)
Question
Number
(a)(i)
Mark
(1)
flowing into lakes
/ washing into lakes
(accept streams,
rivers for lakes)
(2)
excessive/overgrowt
h of algae/plants on
the surface
(1)
Answer
Acceptable answers
Mark
90780=0.115(1) ×
100 = 11.5(%) (1)
Answer
Accept 12%
Acceptable answers
(2)
Mark
energy lost as heat
(2)
Acceptable answers
Mark
Question
Number
(a)(ii)
Any two from the following points
• respiration (1) • excretion / egestion (1)
• temperature regulation (1) • movement /
exercise • not all eaten (1)
Question
Answer
Number
(b)
Any two from the following points: • keep
them in a warm environment (1) • restrict
their movement (1) • provide high energy /
low wastage / easily digestible food (1)
• treat parasites (1)
Question
Answer
Number
(c)(i)
C
Question
Answer
Number
(c)(ii)
An explanation linking the following points:
• bacteria provides nitrates for the plants (1)
• (by) nitrogen-fixation / converting nitrogen
into nitrates (1) • (nitrates) provide protein /
for growth (1)
Ignore feed more
Acceptable answers
(2)
Mark
Acceptable answers
(1)
Mark
Accept nitrogenfixing bacteria
(3)
Q3.
Answer
Acceptable
Mark
answers
(b)
An explanation linking the first bullet point with an explanation including
 increase in carbon dioxide levels (1) Plus one of the following
 respiration/ burning of fossil fuels/ waste decaying (1)
 deforestation leading to reduced photosynthesis (1)
maximum 1 mark for reason accept named fossil fuel
(2)
(c)
lichen / blackspot
other air quality
fungus
indicator species eg.
canaries / algae /
moss / peppered
moths
(d)
An explanation
linking three of the
following including
Ignore encourages
points
algae to
grow
Accept
 algal bloom/
bacteria/microorgani
increased algae /
sms for
more algae (1)
decomposers No
 blocks sunlight
(from plants growing mark for 'plants die'
Do not give mark for
on the bottom of the
just low oxygen this
lake/river) (1)
must be linked to
 so stops
microorganisms
photosynthesis (1)
(respiring)
 (plants die) so
decomposers break
them down
 which use
oxygen for
respiration /oxygen
depletion (1)
(1)
(3)
Q4.
Question
Number
Answer
Acceptable answers
C (1) least amount of
freshwater shrimps
found at C (1)
Reference to
freshwater shrimps
as indicator species
freshwater shrimps
can only survive in
clean water / cannot
survive in polluted
water more shrimps
die in polluted water
Mark
(2)