PLACE
LABEL
HERE
Tasmanian Secondary Assessment Board
Tasmanian Certificate of Education
External Assessment
1999
BY826 BIOLOGY
SECTION A
Time: 35 minutes
On the basis of your performance in this examination, the examiners will provide a rating of A, B, C or
D on the following criterion taken from the syllabus statement:
Criterion 3
Pages:
Questions:
©
Demonstrate understanding and knowledge of biological
principles and how they apply to the molecular and cellular levels
of biological organisation.
7
3
Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian
Secondary Assessment Board.
BY826 Biology
CANDIDATE INSTRUCTIONS
Answer ALL questions. Answers must be written in the spaces provided on the examination paper.
Information written outside the spaces will not necessarily be taken into consideration.
Candidates are reminded that spelling and expression which make it difficult for the examiner to
understand what candidates mean, will result in loss of marks.
________________________________________________________________________________
Question 1
(a) (i)
In what part of a plant or animal would you expect to find the cell above? Give two
reasons.
(3 marks)
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(ii)
What evidence suggests that this drawing of a cell was made from observations using an
electron microscope?
(1 mark)
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Question 1 continues opposite.
Page 2
BY826 Biology
Question 1 (continued)
(b)
Complete the table by matching the everyday (non-biological) terms in the list below with the
biological features found in a cell, as identified in the table.
(3 marks)
•
•
•
•
•
•
manufacturing assembly line unit
solar panel
security fence
pack and wrap department
transport canal system
power generator
Biological Feature Found in a Cell
Matching Everyday Terms
Cell membrane/wall
Ribosome
Chloroplast
Golgi apparatus
Mitochondrion
Endoplasmic reticulum
(c)
‘The size and shape of a cell limit the maximum metabolic rate it can attain.’ Briefly explain the
scientific basis of this statement.
(3 marks)
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Total Question 1:
Page 3
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BY826 Biology
Question 2
Some of the activities of a cell from a green plant can be represented as shown below.
C O2
light
energy
H2O
chlorophyll
O2
Part A
(a)
O2
H2O
chemical energy
C O2
Part B
CARBOHYDRATE
Give the usual names of the processes summarised within the cell section labelled:
(1 mark)
Part A: ………………………………………………………………………………….………
Part B: ………………………………………………………………………………….………
(b) (i)
A researcher measured the concentration of oxygen in the air around some cells placed in
strong sunlight. He found that as time passed, the oxygen concentration continued to
increase. Explain this observation.
(2 marks)
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(ii)
The researcher then changed the light intensity until it was observed that the concentrations
of oxygen and carbon dioxide in the surrounding air remained constant. Explain this
observation.
(2 marks)
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(iii) Was the light intensity increased or reduced in comparison with the conditions in part (b)
(i) above?
(1 mark)
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Question 2 continues opposite.
Page 4
BY826 Biology
Question 2 (continued)
(c)
The browning of peeled apples on exposure to air is catalysed by the enzyme phenol oxidase.
Explain the following statements to show your understanding of enzyme action.
(i)
Placing peeled apples in the refrigerator can slow the browning process.
(2 marks)
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(ii)
Boiling apples as soon as they are peeled can prevent the browning process.
(2 marks)
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(iii) Using your knowledge of enzyme action, suggest another method of preventing browning
and explain why it is effective.
(2 marks)
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Total Question 2:
Page 5
/12
BY826 Biology
Question 3
(a)
Researchers investigating the responses of sandworms to environmental change performed the
following experiment. They collected fifty worms of approximately equal size and organised
them into five groups of ten worms each. The five groups of worms were then weighed.
Each group of worms was then placed in a separate jar. They poured into each of the first four
jars a different concentration of saline (salt) solution: 0.5, 1.0, 1.5 and 2.0 molar (M) solutions
respectively. The fifth jar was filled with normal seawater. The worms were left in the solutions
for one hour and then reweighed (worms can survive extremes of salt concentration for a
number of hours). The weight change for each group of worms was then determined. The
results are shown below.
1
0.5 M solution
+10.0 g
2
3
4
5
1.0 M solution
1.5 M solution
2.0 M solution
normal seawater
+5.0 g
0.0 g
–10.0 g
0.0 g
weight change (g)
(i)
What process is responsible for the changes in the mass of the sandworms?
(1 mark)
…………………………………………………………………………………………….
(ii)
Explain why the worms in the 0.5 M solution and the 1.0 M solution increased in mass
(on average), while those in the 1.5 M solution did not.
(3 marks)
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(iii) Estimate the salt concentration of normal seawater from the results.
(1 mark)
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Question 3 continues opposite.
Page 6
BY826 Biology
Question 3 (continued)
(iv)
There are two different approaches to surviving in aquatic environments with a wide range
of salt concentrations. What are they and which one does the sandworm mostly rely on?
(2 marks)
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(b)
The diagrams below show a single pair of homologous chromosomes at different times during
cell (nuclear) division. Each diagram represents a single stage of the division.
I
(i)
II
III
IV
State the sequence in which cell division would occur using the numbers indicated above
each diagram.
(2 marks)
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(ii)
What is happening in IV? Explain the genetic consequences of this process.
(4 marks)
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Total Question 3:
Page 7
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PLACE
LABEL
HERE
Tasmanian Secondary Assessment Board
Tasmanian Certificate of Education
External Assessment
1999
BY826 BIOLOGY
SECTION B
Time: 35 minutes
On the basis of your performance in this examination, the examiners will provide a rating of A, B, C or
D on the following criterion taken from the syllabus statement:
Criterion 4
Pages:
Questions:
©
Display understanding and knowledge of biological principles and
how they apply to the organism.
9
3
Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian
Secondary Assessment Board.
BY826 Biology
CANDIDATE INSTRUCTIONS
Answer ALL questions. Answers must be written in the spaces provided on the examination paper.
Note: Candidates have a choice in Question 5. Answer parts (a) and (b) OR parts (c) and
(d).
Information written outside the spaces will not necessarily be taken into consideration.
Candidates are reminded that spelling and expression which make it difficult for the examiner to
understand what candidates mean, will result in loss of marks.
________________________________________________________________________________
Page 2
BY826 Biology
Question 4
In higher animals the three main functions of digestive systems are mechanical breakdown, chemical
digestion and absorption.
(a)
Name a complex multicellular animal you have studied this year and briefly explain how it is
adapted to carry out each of these functions.
(6 marks)
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(b)
Explain how having a digestive system with two openings makes these processes efficient.
(2 marks)
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(c)
Outline the three ways in which adaptations to allow efficient absorption in a mammal are
similar to those used to make gas exchange efficient.
(3 marks)
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Total Question 4:
Page 3
/11
BY826 Biology
Question 5
Answer parts (a) and (b) of this question
A
OR
parts (c) and (d).
C
B
D
Left atrium
Right atrium
Left ventricle
Right ventricle
A
(a)
(i)
State which vessel(s) carry oxygenated blood using the letter(s) indicated in the diagram
above.
(1 mark)
…………………………………………………………………………………………….
(ii)
Consider the effects of a heart attack on the function of the organ above. If the heart
attack was the result of damage to the muscular wall of the left ventricle so that the left
ventricle was no longer able to pump the same amount of blood as it did in normal
circumstances:
What would be the effect on the blood pressure measured in the main artery of the arm?
(1 mark)
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What would be the effect on the blood pressure in vessel D? Explain your answer.
(2 marks)
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Question 5 continues opposite.
Page 4
BY826 Biology
Question 5 (continued)
(iii) As a result of such a heart attack there is often a build up of fluid in the alveoli of the lung.
Explain why this accumulation of fluid would occur.
(2 marks)
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(b)
Consider the relationship between the circulatory system and the nephron to answer the
following questions.
(i)
Which two things combine to cause fluid to move from the capillaries in the glomerulus
into the Bowmans capsule?
(1 mark)
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(ii)
What causes water to return to the capillaries of the nephron?
(1 mark)
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(iii) The concentrations of salts and urea in the blood leaving the kidney differ from those
entering the kidney. Explain why this is important.
(3 marks)
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(iv)
What is the main advantage of having around a million tiny nephrons in each kidney in
terms of efficiency?
(1 mark)
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Question 5 continues over the page.
Page 5
BY826 Biology
Question 5 (continued)
OR
(c)
Refer to the diagram below and answer the questions which follow.
A
I
II
III
Enlarged view of
Section A
IV
V
VI
(i)
Name the process by which water vapour escapes from structure IV and name the
structure itself.
(1 mark)
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(ii)
…………………………………………………………………………………………….
Why does this process occur when these structures are open?
(2 marks)
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(iii) Give two features that help minimise water loss from this leaf and outline how they help
to do this.
(2 marks)
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(iv)
…………………………………………………………………………………………….
Give one other method of water conservation that leaves use that is not shown in the
diagram above.
(1 mark)
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Question 5 continues opposite.
Page 6
BY826 Biology
Question 5 (continued)
(d) The graphs below show the daily patterns in the rate of transpiration and the rate of carbon
dioxide uptake of a particular plant on a hot summer’s day (February) and on a cool winter’s
day (June). The rate of transpiration and the rate of carbon dioxide uptake are each measured in
arbitrary units.
Rate of
Transpiration
June
February
February
Time of Day (hour)
June
Rate of Carbon
Dioxide Uptake
February
Time of Day (hour)
(i)
Explain why the daily pattern of transpiration is not the same in summer as in winter.
(3 marks)
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(ii)
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Explain why the daily pattern of transpiration is related to the daily pattern of carbon
dioxide uptake.
(2 marks)
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(iii) What information from the graph could be best used to decide on which of the two days
the plant would make the most growth?
(1 mark)
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Total Question 5:
Page 7
/12
BY826 Biology
Question 6
(a)
Explain why it can be said that ‘to control the concentration of dissolved substances in the blood
is to control the whole body’s concentrations’.
(4 marks)
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Has Trait
No Trait
I
1
2
II
3
4
5
6
7
8
15
16
17
18
9
10
11
III
12
13
14
19
IV
20
(b) (i)
21
22
23
24
25
26
27
Is the pedigree in the diagram above a dominant or recessive character? Explain.(2 marks)
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(ii)
Is the pedigree a sex linked or non-sex linked (autosomal) character? Explain. (2 marks)
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Question 6 continues opposite.
Page 8
BY826 Biology
Question 6 (continued)
(c)
Guinea pigs are small pets. Their coat colour and length of hair are under genetic control. Two
of the genes involved and their allelic forms are given below. Black is dominant over white and
Short hair is dominant over long hair.
Gene 1
Black
white
B
b
Gene 2
Short
long
S
s
In one particular cross, a black short haired female was crossed with a white long haired male.
Of the nine offspring that were produced, five were black short haired and four were white short
haired. What were the genotypes of the parents? Show your working.
(4 marks)
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Total Question 6:
Page 9
/12
PLACE
LABEL
HERE
Tasmanian Secondary Assessment Board
Tasmanian Certificate of Education
External Assessment
1999
BY826 BIOLOGY
SECTION C
Time: 35 minutes
On the basis of your performance in this examination, the examiners will provide a rating of A, B, C or
D on the following criterion taken from the syllabus statement:
Criterion 5
Pages:
Questions:
©
Demonstrate understanding and knowledge of biological
principles and how they apply to the interrelationships between
organism and environments.
7
3
Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian
Secondary Assessment Board.
BY826 Biology
CANDIDATE INSTRUCTIONS
Answer ALL questions. Answers must be written in the spaces provided on the examination paper.
Information written outside the spaces will not necessarily be taken into consideration.
Candidates are reminded that spelling and expression which make it difficult for the examiner to
understand what candidates mean, will result in loss of marks.
________________________________________________________________________________
Question 7
Research into a forest ecosystem produced data on the diets of some of the common animals, as
shown below.
Animal
Diet
Small mammals
Seeds, insects
Owls
Small mammals, lizards
Insects
Leaves
Hawks
Small mammals, small birds
Lizards
Insects
Small birds
Seeds, insects
(a)
Construct a food web to show the feeding relationships of the organisms listed in the table
above.
(4 marks)
(b)
Name
the niche of the owls;
(1 mark)
…………………………………………………………………………………………………...
and the niche of the insects.
(1 mark)
…………………………………………………………………………………………………...
Question 7 continues opposite.
Page 2
BY826 Biology
Question 7 (continued)
(c)
The data indicates that some animals are in competition for resources. Name two competing
animals and the reason they compete.
(1 mark)
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(d)
An orchard close to the forest was sprayed with a fungicide which, at the recommended levels of
application, was not directly harmful to animals. Some time later, dead owls and hawks were
found in the forest. No other animals were affected. Briefly explain how these deaths might
have been caused.
(4 marks)
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Total Question 7:
Page 3
/11
BY826 Biology
Question 8
(a)
Listed below are the components and processes that together make up a simplified version of the
global carbon cycle.
Components: A
B
C
D
E
plant and animal residues, including fossil fuels
animals
bacteria and fungi of decay
carbon dioxide in the atmosphere
green plants
Processes:
photosynthesis
respiration
combustion
consumption
1
2
3
4
In the diagram below write the correct letter for each component in the respective box and the
correct number of each process on the relevant dotted line. Note: a process may appear more
than once.
(4 marks)
(b)
The carbon cycle is in some ways linked to the movement of energy in ecosystems.
(i)
What is the important link between the carbon cycle and the movement of energy in an
ecosystem?
(1 mark)
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(ii)
Explain the important difference(s) between the carbon cycle and the movement of energy
in an ecosystem.
(2 marks)
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Question 8 continues opposite.
Page 4
BY826 Biology
Question 8 (continued)
(c)
In England prior to the industrial revolution, people’s lives were centered around the village they
were born in. For most, walking was the only option. Few people travelled more than a few
miles beyond their own village and there was little contact with surrounding villages. It had been
said that the invention and widespread adoption of the bicycle was the single greatest factor in
improving the genetic health of the nation in centuries.
Use your understanding of biology and in particular, reproduction and genetics, to explain why
this is arguably so.
(4 marks)
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Total Question 8:
Page 5
/11
BY826 Biology
Question 9
(a)
The regulation of population sizes in a complex ecosystem is an example of homeostasis.
Population numbers are influenced by:
•
•
•
interaction between members of the same population
interaction with members of other species
non-living factors
Using examples where appropriate, discuss to what extent each of the above factors contributes
to this homeostatic control of populations.
(6 marks)
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Question 9 continues opposite.
Page 6
BY826 Biology
Question 9 (continued)
(b)
Cabbage is one of the most popular vegetables in Southeast Asia and is grown throughout the
year. A serious pest of the cabbage is the diamondback moth, Plutella xylostella. The
diamondback moth has been controlled by spraying the cabbages with insecticides. One of
these insecticides is obtained from the soil bacterium, Bacillus thuringiensis. The bacteria
produce a toxin (abbreviated name is Bt) which has been an effective insecticide against the
diamondback moth and is also an environmentally friendly chemical. Since 1990, strains of the
diamondback moth that are resistant to the Bt toxin have been increasing in the population.
(i)
What change has occurred in the frequency of the Bt-resistant allele in the diamondback
moth population since 1990?
(1 mark)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
(ii)
Explain the steps that have occurred to bring about this change in the frequency of the Btresistant allele in the population of diamondback moths.
(4 marks)
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Total Question 9:
Page 7
/11
PLACE
LABEL
HERE
Tasmanian Secondary Assessment Board
Tasmanian Certificate of Education
External Assessment
1999
BY826 BIOLOGY
SECTION D
Time: 35 minutes
On the basis of your performance in this examination, the examiners will provide a rating of A, B, C or
D on the following criteria taken from the syllabus statement:
Criterion 8
Pages:
Questions:
©
Develop feasible hypotheses and design controlled experiments to
test hypotheses.
7
3
Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian
Secondary Assessment Board.
BY826 Biology
CANDIDATE INSTRUCTIONS
Answer ALL questions. Answers must be written in the spaces provided on the examination paper.
Information written outside the spaces will not necessarily be taken into consideration.
Candidates are reminded that spelling and expression which make it difficult for the examiner to
understand what candidates mean, will result in loss of marks.
________________________________________________________________________________
Question 10
(a)
The graph above shows data from an experiment on camel physiology.
hypothesis that was being tested by this experiment.
Formulate an
(4 marks)
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(b)
The European starling, a small bird, was introduced into eastern Australia during the nineteenth
century. Since then it has spread throughout eastern Australia and become a pest but it has not
established a population in Western Australia. Give a credible hypothesis that accounts for the
absence of starlings in Western Australia.
(3 marks)
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Question 10 continues opposite.
Page 2
BY826 Biology
Question 10 (continued)
(c)
Many gardening books advise against growing broad beans and onions alongside each other
because the yield of both crops is reduced. If you were provided with a supply of onion root
extract, how would you test the hypothesis that the extract is responsible for inhibiting the yield
of broad bean plants?
(6 marks)
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Total Question 10:
Page 3
/13
BY826 Biology
Question 11
An egg producer experimented with different feed rations with the aim of increasing production whilst
reducing the cost of feed per egg. The data from two experiments are shown below.
Experiment 1
Protein concentration in feed (%)
10
11
12
13
14
15
16
Total vitamin level (mg/kg)
100
100
100
100
100
100
100
Cost of feed per 100 hens per day ($)
6.00
7.00
7.50
8.00
8.50
8.75
9.00
Number of eggs per 100 hens per day
60
70
75
80
85
80
80
Experiment 2
Protein concentration in feed (%)
14
14
14
14
14
14
14
Total vitamin level (mg/kg)
50
75
100
125
150
175
200
Cost of feed per 100 hens per day ($)
8.00
8.25
8.50
8.75
9.00
9.25
9.50
Number of eggs per 100 hens per day
70
80
85
90
95
95
95
(a)
(b)
(c)
(d)
What is the independent variable in
(2 marks)
Experiment 1
………………………………………………………………………………..
Experiment 2
………………………………………………………………………………..
State two variables that were controlled in Experiment 1.
(1 mark)
(i)
…………………………………………………………………………………………….
(ii)
…………………………………………………………………………………………….
State two other variables that would also need to be controlled in both experiments.
(1 mark)
(i)
…………………………………………………………………………………………….
(ii)
…………………………………………………………………………………………….
What was being investigated in Experiment 2?
(2 marks)
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
Question 11 continues opposite.
Page 4
BY826 Biology
Question 11 (continued)
(e)
Give details of how you could present the experimental results to most clearly represent them,
keeping in mind the egg producer’s aims.
(3 marks)
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
(f)
What follow up action would you recommend for this investigation, if any?
(2 marks)
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
Total Question 11:
Page 5
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BY826 Biology
Question 12
(a)
The sperm count of men has declined since 1940. The average sperm count in 1940 was 113
million per mL of seminal fluid. By 1990, it had fallen an astounding 50%. Scientists believe
these trends could be linked to the chemicals used in our society. These chemicals include
industrial chemicals and female hormones used in food production.
(i)
Give two significant problems in running a controlled experiment to test the link between
increased exposure to chemicals in everyday life and the reduction in sperm count.
(2 marks)
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
(ii)
How could you investigate evidence for this link without directly experimenting on
humans? In your answer consider the factors that would affect the reliability of this
evidence and how you could still ensure it was as meaningful as possible.
(5 marks)
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
…..………………………………………………………………………………………...
Question 12 continues opposite.
Page 6
BY826 Biology
Question 12 (continued)
(b)
The following graph shows the estimated density of the rat, Rattus exulans, which feeds on grass
seeds, and the estimated density of grass stalks with seed heads per square metre. The data
presented in these graphs was taken over a three year period from the beginning of 1986 to the
end of 1988.
200
50
180
160
40
140
120
30
100
80
20
60
40
10
20
0
(i)
Number of Grass Stalks with
Seed Heads per Square Metre
Number of Rats per Hectare
Rats
Grass Stalks
0
Jan Mar May Jul
Sep Nov Jan Mar May Jul
Sep Nov Jan Mar May Jul
1986
1987
1988
Sep Nov
Briefly outline a procedure which could be used to collect the data for the density of the
rat population.
(2 marks)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
(ii)
Briefly outline a procedure which could be used to collect the data for the density of the
grass stalks with seed heads.
(2 marks)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
Total Question 12:
Page 7
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PLACE
LABEL
HERE
Tasmanian Secondary Assessment Board
Tasmanian Certificate of Education
External Assessment
1999
BY826 BIOLOGY
SECTION E
Time: 35 minutes
On the basis of your performance in this examination, the examiners will provide a rating of A, B, C or
D on the following criterion taken from the syllabus statement:
Criterion 9
Pages:
Questions:
©
Analyse, interpret and evaluate information and data gained (from
individual investigations and the investigations of others) and to
evaluate the methods used and conclusions drawn from these
investigations.
9
3
Copyright for part(s) of this examination may be held by individuals and/or organisations other than the Tasmanian
Secondary Assessment Board.
BY826 Biology
CANDIDATE INSTRUCTIONS
Answer ALL questions. Answers must be written in the spaces provided on the examination paper.
Information written outside the spaces will not necessarily be taken into consideration.
Candidates are reminded that spelling and expression which make it difficult for the examiner to
understand what candidates mean, will result in loss of marks.
_______________________________________________________________________________
Question 13
(a)
The release of pollutants into rivers, lakes and the ocean can result in the death of aquatic life. It
can also affect the health of people who drink or swim in the water or who eat contaminated
organisms in the food chain of these environments.
One way to check the amount of pollution in a river is to measure the volume of oxygen
dissolved in the water. Another way is to see what sort of animals are living in it.
The table below shows the results of both methods. Use the information in the table to help you
answer the questions which follow.
Level of
Pollution
Types of Animals Present
Volume of Oxygen Measured
in ppm of Water
Fish
Others
at 5˚C
at 20˚C
none
grayling
salmon
trout
mayfly nymph
stonefly nymph
8
5
very low
dace
roach
freshwater shrimp
snail
6
4
moderate
gudgeon
bloodworm
water louse
4
3
high
none
rat-tailed maggot
sludge worm
2
1
(i)
Which two animals would you expect to find in water with high levels of pollution?
(1 mark)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
(ii)
As the level of pollution increases what happens to the amount of dissolved oxygen in the
water?
(1 mark)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
Question 13 continues opposite.
Page 2
BY826 Biology
Question 13 (continued)
(iii) As the water temperature increases what happens to the amount of oxygen that is dissolved
in the water?
(1 mark)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
(iv)
What volume of oxygen, measured in parts per million (ppm) would you expect to find in
a trout river at 10˚C?
(1 mark)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
(v)
Some fish farmers raise trout. Explain what advice you would give to fish farmers in
regard to maintaining a water supply suitable for trout.
(2 marks)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
(b) Outline two problems associated with the sampling of animals for such a study.
(2 marks)
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
Question 13 continues over the page.
Page 3
BY826 Biology
BLANK PAGE
Page 4
BY826 Biology
Question 13 (continued)
(c)
The graph below shows the results of data collected over 40 years on the global concentration of
chlorine in the atmosphere in parts per billion by volume (ppbv) and the concentration of ozone
over Antarctica in October.
(i)
State a conclusion that could be drawn from this data.
(2 marks)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
(ii)
Data collection ceased in 1990 but use the graph to estimate the concentration of chlorine
in the atmosphere in 1994.
(1 mark)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
(iii) Using the example above, explain how running a long term study can help in reaching
more reliable conclusions.
(2 marks)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
Total Question 13:
Page 5
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BY826 Biology
Question 14
(a)
Stony corals are small animals that live in cups of calcium carbonate that they have deposited.
Colonies of these animals are responsible for building the large calcium carbonate formations
known as coral reefs. The cells lining the pharynx of most reef-building corals are known to
contain algae. A researcher performed the following experiment in which the importance of
algae and light to the rate of calcium carbonate deposition were determined. Note: algae can be
removed without damage to the corals.
Pharynx
Algae
Algae intact
Exposed
to light
Calcium carbonate cup
Kept in
darkness
Algae removed
Exposed
to light
Kept in
darkness
One day after the processes indicated in the diagram above were carried out, equal amounts of a
solution containing radioactive calcium ions were added to the seawater around each of the
corals. A week later the rate at which radioactive calcium had been deposited as calcium
carbonate was measured. The results are shown below.
Rate of Calcium Deposition by Corals (micrograms of calcium per hour)
With Algae
(i)
Without Algae
Light
Dark
Light
Dark
1.63
0.81
0.26
0.26
State whether or not the results support each of the following hypotheses. Give a reason
for your answer.
In the absence of algae, light increases the rate of calcium deposition by corals.
(1 mark)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
Question 14 continues opposite.
Page 6
BY826 Biology
Question 14 (continued)
The presence of algae increases the rate of calcium carbonate deposition by corals in the
light.
(1 mark)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
The presence of algae has no effect on calcium carbonate deposition in the dark. (1 mark)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
(ii)
From the results obtained in the experiment, would you expect any growth of coral reefs at
ocean depths where light fails to penetrate? Explain.
(2 marks)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
…………………………………………………………………………………………….
(iii) Suggest one environmental factor that might affect the growth of coral reefs by
influencing light intensity.
(1 mark)
…………………………………………………………………………………………….
…………………………………………………………………………………………….
Question 14 continues over the page.
Page 7
BY826 Biology
Question 14 (continued)
(b)
In a series of laboratory experiments carried out in the 1950s, two species of flour beetle,
Trilobium confusum and T. castaneum, were kept together in different environmental
conditions. It was discovered that when reared together only one species survived. Results of
some of the experiments are shown below.
Temperature ˚C
Relative Humidity %
% of Times
T. confusum Wins
% of Times
T. castaneum Wins
24
30
100
0
24
70
71
29
29
30
87
13
29
70
14
86
34
30
90
10
34
70
0
100
Consider the data and determine what physical conditions favour the survival of each species.
Give evidence from the data to support your answer.
(5 marks)
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
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Total Question 14:
Page 8
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BY826 Biology
Question 15
In 1926 a British scientist fed leaves covered with soot to twenty larvae from a female peppered moth
which he had caught in the woodland near his home. This moth had a light-coloured body and wings.
He permitted the twenty larvae to go through a normal life cycle and eventually they became lightcoloured adult moths that in turn were allowed to mate and produce another generation of offspring.
When the scientist examined these offspring, he reported that 8% had a dark coloured body and
wings. He claimed that the diet of soot had caused mutation to the dark colour.
(a)
Do you think that the claims made by the scientist were valid? Explain
(3 marks)
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
(b)
Discuss two major faults in the design of this experiment.
(4 marks)
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
(c)
Suggest three other improvements to the original experimental design.
(3 marks)
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
…………………………………………………………………………………………………...
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Total Question 15:
Page 9
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