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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS
General Certificate of Education
Advanced Subsidiary Level and Advanced Level
9693/02
MARINE SCIENCE
Data-Handling and Free-Response
For Examination from 2008
SPECIMEN PAPER
1 hour 15 minutes
Candidates answer Section A on the question paper.
Additional Materials:
Answer Booklet/Paper
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name on all the work you hand in.
Write in dark blue or black pen on both sides of the paper.
You may use a soft pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, highlighters, glue or correction fluid.
Answer all questions.
Write your answers in the spaces provided on the question paper.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
For Examiner's Use
1
2
Total
This document consists of 7 printed pages and 1 blank page.
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Section A
For
Examiner's
Use
Answer both questions in this section.
1
An investigation was carried out into the uptake of nitrate (NO3–) ions on a coral reef flat.
The investigation was designed to test the hypothesis that:
Organisms on the reef flat remove nitrate ions from the water as it flows over them.
Fig. 1.1 shows the relationship of the reef flat to the open sea, the reef crest and the land.
Sea water flows in over the reef crest and then continues over the reef flat.
direction of water movement
reef
crest
ocean
reef flat
horizontal scale
500
0
1000
1500
2000
distance from reef crest / m
Fig. 1.1
The researchers took water samples at different distances from the reef crest.
The concentration of nitrate ions in each sample was measured. This was repeated on the
next day. The results are shown in Fig. 1.2.
August 8
August 9
NOX / µM
0.2
0.15
0.1
0
200
400
600
800
1000 1200 1400
distance from reef crest / m
Fig. 1.2
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(a) Suggest which organisms living on the coral reef flat take nitrate ions from the water,
and explain your suggestion.
For
Examiner's
Use
[2]
(b) With reference to Fig. 1.2, describe the relationship between the concentration of
nitrate ions in the water and the distance from the reef crest.
[2]
(c) (i) Do the results of this investigation support or refute the hypothesis being tested?
Explain your answer.
[2]
(ii) State one reason why these results should be regarded with uncertainty.
[1]
(iii) Suggest one way in which this uncertainty could be reduced.
[1]
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(d) As the water flows over the reef flat, its velocity decreases. Previous investigations had
shown a negative correlation between distance from the reef crest and water velocity –
that is, the water slows down as it flows over the reef flat. The researchers used their
results to formulate a new hypothesis:
The rate of uptake of nitrate ions from the water by the organisms on the reef is
determined by the rate of flow of water across them.
(i) Explain why the velocity of the water decreases as it flows over the reef flat.
[2]
(ii) Explain how the results from the first experiment could have led the researchers to
formulate their new hypothesis.
[2]
[Total: 12]
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2
(a) Fig. 2.1 shows the surface salinity of the world’s oceans. The figures are in parts per
thousand. The measurements were taken in August.
150 °W 120 °W
90 °W
Arctic Circle
60 °N
60 °W
33
32
0°
30 °E
60 °E
90 °E
120 °E 150 °E 180 °E
32
34
33
35
33
34
36
34
30 °N
33
35
35
37
Tropic of Cancer
34
30 °W
36
32
36
35
0° Equator
34
32
33
35
34
36
35
36
30 °S
35
35
35
37
Tropic of Capricorn
For
Examiner's
Use
35
34
35
35
34
34
60 °S
Antarctic Circle
Fig. 2.1
(i) With reference to Fig. 2.1, describe how surface salinity varies with distance from
land.
[1]
(ii) Suggest an explanation for the pattern that you have described.
[2]
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evaporation –
precipitation / cm
(b) Fig. 2.2 shows the difference between evaporation and precipitation, measured in cm,
at latitudes between 40°N and 50°S.
+50
dry
0
wet
–50
40°N
30°N
20°N
10°N
0°
10°S
20°S
30°S
40°S
latitude
50°S
Fig. 2.2
Surface salinity tends, in general, to be slightly lower at high latitudes and the Equator
than at intermediate latitudes.
Use the information in Fig. 2.2 to explain this relationship between surface salinity and
latitude.
[3]
(c) Mangrove trees are able to survive in saline water. Describe two environmental factors,
other than salinity, that may lead to the development of mangrove forest along a shore,
rather than another type of ecological community.
1
2
[2]
[Total: 8]
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Section B
Answer both questions in this section.
3
(a) With reference to examples within a marine ecosystem, describe the meaning of the
term trophic level.
[2]
(b) Explain how populations of marine predators and prey may be inter-related.
[5]
(c) Discuss the possible benefits of shoaling in tuna and sardines.
[8]
[Total: 15]
4
(a) Describe what is meant by the term atoll.
[2]
(b) Explain the Darwin-Dana-Daly theory of atoll formation.
[5]
(c) Discuss the evidence that supports this theory.
[8]
[Total: 15]
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