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)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
(iii) State the effects of nitrates on plant growth.
(1)
..............................................................................................................................................
..............................................................................................................................................
Q2.
The overuse of fertilisers can cause eutrophication.
Explain the effects of eutrophication that may lead to the death of aquatic animals.
(3)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
Q3.
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.
Describe what will happen to the organisms in the stream when nitrates leak from the factory.
(4)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
Q4.
* Explain how an increase in the production of pollutants can be due to an increase in human
population.
Include both air and water pollution in your answer.
(6)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
Q5.
The human population is increasing.
Explain how this could change the concentration of carbon dioxide in the atmosphere.
(2)
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
..............................................................................................................................................
Mark Scheme
Q1.
Answer
(i)
(ii)
(iii)
B - eutrophication
Any two from the
following:
 (over use of)
nitrates / phosphates
fertilisers (1)
 leaching into the
lake(1)
 sewage leakage
into the lake (1)
(plant growth) is
increased / protein is
made(1)
Acceptable
answers
Mark
(1)
flowing into lakes /
washing into lakes
(accept streams,
rivers for lakes)
(2)
excessive/overgrowt
h of algae/plants on
the surface
(1)
Q2.
Answer
Acceptable
answers
Mark
An explanation
linking three of the
following including
points
 algal bloom/
increased algae /
more algae (1)
 blocks sunlight
(from plants growing
on the bottom of the
lake/river) (1)
 so stops
photosynthesis (1)
 (plants die) so
decomposers break
them down
 which use
oxygen for
respiration /oxygen
depletion (1)
Ignore encourages
algae to grow
Accept
bacteria/microorgani
sms for
decomposers No
mark for 'plants die'
Do not give mark for
just low oxygen this
must be linked to
microorganisms
(respiring)
(3)
Q3.
Question
Number
Answer
Acceptable answers
A description of the
process linking four
of the following
points: • algae (on
the surface) of the
stream show rapid
growth (1) • (they)
block light to the
photosynthesising
plants below (1)
• (causing) plants on
the stream bed to die
(1) • decomposers
use up oxygen to
break down these
dead plants (1)
• other organisms
die due to lack of
oxygen (1)
algal bloom occurs /
large increase in
growth of algae /
other plants grow
quickly Accept
microorganisms /
microbes / bacteria
Accept reference to
anaerobic bacteria
can function in
anoxic conditions not against a current
marking point
Mark
(4)
Q4.
Indicative Content
QWC
*
Leve l
1
0
1-2
Mark
A explanation to
include some of the
following Air
pollution
 Humans burn
more fossil fuels
coal/oil/gas
 nitrogen oxides
in car exhausts
 Releasing sulfur
dioxide
 Which causes
acid rain
 carbon dioxide
gas
 causes climate
change
 deforestation
causing increase in
carbon dioxide
 increased
population –
increased respiration
more carbon dioxide
Water pollution
 Humans
produce sewage
 Sewage
contains phosphates
 Phosphates are
water pollutants
 Nitrate pollution
can be caused by
the overuse of
fertilisers
 Nitrate pollution
causes
(6)
eutrophication
No rewardable content
 a limited explanation of how humans
effect pollution – increasing pollution in
either air or water
 the answer communicates ideas using
simple language and uses limited scientific
terminology
 spelling, punctuation and grammar are
used with limited accuracy
2
3-4
 a simple explanation of both air and
water pollution including the effects of one
air and one water pollutant or a detailed
explanation of either air or water pollution
 the answer communicates ideas
showing some evidence of clarity and
organisation and uses scientific terminology
appropriately
 spelling, punctuation and grammar are
used with some accuracy
3
5-6
 a detailed explanation of the effect of
humans on both air and water pollution
including the role of sulphur dioxide or
carbon dioxide and nitrates or phosphates
 the answer communicates ideas clearly
and coherently uses a range of scientific
terminology accurately
 spelling, punctuation and grammar are
used with few errors
Q5.
Answer
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)
Acceptable
answers
Mark
maximum 1 mark for
reason accept
named fossil fuel
(2)