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Transcript
FOR OFFICIAL USE
Total for
Sections
B&C
X008/12/02
NATIONAL
QUALIFICATIONS
2015
T H U R S D A Y , 2 1 m ay
1.00 PM – 3.30 PM
BIOTECHNOLOGY
HIGHER
Fill in these boxes and read what is printed below.
Full name of centre
Town
Forename(s)
Surname
Date of birth
Day
Month
Year
Scottish candidate number
Number of seat
SECTION A (30 Marks)
Instructions for completion of Section A are given on page two.
For this section of the examination you must use an HB pencil.
SECTION B AND SECTION C (100 Marks)
1 (a) All questions should be attempted.
(b) It should be noted that in Section C questions 1 and 2 each contain a choice.
2The questions may be answered in any order but all answers are to be written in the
spaces provided in this answer book, and must be written clearly and legibly in ink.
3Additional space for answers will be found at the end of the book. If further space is
required, supplementary sheets may be obtained from the Invigilator and should be
inserted inside the front cover of this book.
4
The numbers of questions must be clearly inserted with any answers written in the
additional space.
5Rough work, if any should be necessary, should be written in this book and then scored
through when the fair copy has been written. If further space is required, a supplementary
sheet for rough work may be obtained from the Invigilator.
6Before leaving the examination room you must give this book to the Invigilator. If you do
not, you may lose all the marks for this paper.
HTP
*X008/12/02*
©
SECTION A
Read carefully
1Check that the answer sheet provided is for Biotechnology Higher (Section A).
2For this section of the examination you must use an HB pencil and, where necessary, an eraser.
3Check that the answer sheet you have been given has your name, date of birth, SCN (Scottish
Candidate Number) and Centre Name printed on it.
Do not change any of these details.
4If any of this information is wrong, tell the Invigilator immediately.
5If this information is correct, print your name and seat number in the boxes provided.
6The answer to each question is either A, B, C or D. Decide what your answer is, then, using
your pencil, put a horizontal line in the space provided (see sample question below).
7There is only one correct answer to each question.
8Any rough working should be done on the question paper or the rough working sheet, not on
your answer sheet.
9At the end of the examination, put the answer sheet for Section A inside the front cover of
this answer book.
Sample Question
What name is given to a culture of micro-organisms which contains more than one species of
organisms?
AMixed
BPure
CSimple
DComplex
The correct answer is A—Mixed.
horizontal line (see below).
A
B
C
The answer A has been clearly marked in pencil with a
D
Changing an answer
If you decide to change your answer, carefully erase your first answer and, using your pencil, fill in
the answer you want. The answer below has been changed to D.
A
[X008/12/02]
B
C
D
Page two
SECTION A
All questions in this Section should be attempted.
Answers should be given on the separate answer sheet provided.
1. Which of the following statements is true for
yeast?
A
Multicellular and reproduces by spores.
B
Unicellular and reproduces by spores.
C
Multicellular and reproduces by budding.
D
Unicellular and reproduces by budding.
4.Which of the following diagrams represents the
structure of a virus?
A
DNA
membrane
capsid
2. Which of the following structures is produced
only during sexual reproduction in Mucor?
AMycelium
B
BSporangium
RNA
CZygospore
D
DNA
Multinucleate hyphae
capsid
envelope
3. The diagram below shows a fungal growth curve.
C
DNA
C
capsid
D
Cell
number
B
D
A
DNA
RNA
capsid
Time
Section D of the curve is described as
A
latent phase
B
senescent phase
C
exponential phase
D
lag phase.
[X008/12/02]
[Turn over
Page three
5. Bacterial cells grow then divide to produce two
daughter cells. In nutrient rich medium, the
cells grow bigger than normal and cell division
is inhibited.
A
Aerobic growth of yeast
Which of the following statements explains
these observations?
B
Anaerobic growth of yeast
C
Anaerobic growth of micro-organisms
A
D Aerobic and anaerobic growth of microorganisms
B Earlier binary fission, leading to more
daughter cells.
C
D Earlier binary fission, leading to larger
daughter cells.
Delayed binary fission, leading to more
daughter cells.
7. Which of the following statements describes
fermentation?
Delayed binary fission, leading to larger
daughter cells.
Mean generation time (minutes)
6.The graph below shows the effect of
temperature on the mean generation time of
three different bacteria species (P, Q and R).
120
90
60
R
Q
30
P
0
20
25
30
35
Temperature (ºC)
40
The number of generations per hour for
species P at 30 ºC is
A0·75
B1
C1·33
D2.
[X008/12/02]
Page four
8. The table below shows the number of fragments produced when a piece of DNA was digested with
different combinations of three restriction enzymes: Sal I, EcoR I, and Hpa I.
Combination of restriction enzymes
Number of fragments produced
Sal I and EcoR I
4
Sal I and Hpa I
3
Sal I, EcoR I and Hpa I
5
Which of the following correctly shows the position of the recognition sites for all three restriction
enzymes on this piece of DNA?
A
Sal I
Hpa I
Sal I
B
EcoR I Sal I
EcoR I
Hpa I
C
Sal I
EcoR I
Hpa I EcoR I
D
Sal I Hpa I
EcoR I
Sal I
EcoR I
9. Heat can be used to separate the DNA strands
in a double helix.
11.A suitable control for an experiment to
transform E.coli would contain
Increasing temperature separates the strands of
DNA by
A
breaking down bases
B
E.coli, and media containing antibiotic
B
breaking hydrogen bonds
C
breaking down nucleotides
C
E.coli, plasmid
antibiotic
D
breaking sugar-phosphate bonds.
BProtoplasts
[X008/12/02]
media
without
12. T lymphocytes mediate an immune response
by
A activating macrophages to kill microorganisms
B producing antibodies to attack microoganisms
C activating lysosomes
organisms
D producing enzymes to attack microorganisms.
Page five
[Turn over
CYeast
DBacteria
and
D
E.coli, and media without antibiotic.
10. Which of the following can be used as cloning
vectors?
AViruses
A
E.coli, plasmid and media containing
antibiotic
to
kill
micro-
13. Which line in the table below correctly identifies the type of risk assessment and its description?
Simple
Generic
Novel
From first principles
Familiar hazard, well known
control measures
Uses authoritative code of
practice
B
Familiar hazard, well known
control measures
Uses authoritative code of
practice
From first principles
C
Familiar hazard, well known
control measures
From first principles
Uses authoritative code of
practice
From first principles
Uses authoritative code of
practice
Familiar hazard, well known
control measures
A
D
14. The effect of an antibiotic on three different
bacterial species (X, Y and Z) was tested by
spreading each species of bacteria on an agar
plate and adding a disk soaked in the antibiotic.
The plates were incubated for 24 hours at
30 ºC, then examined for inhibition of growth.
Bacteria X
Bacteria Y
Bacteria Z
15. The ingredients of two different types of media
are shown below.
Medium P:
sodium citrate, potassium
hydrogen phosphate, ammonium nitrate,
magnesium sulphate, vitamin B
Medium Q: peptone, yeast extract, sodium
chloride, beef extract
Which line in the table below correctly
describes these two types of media?
Medium P
disk soaked in antibiotic
Which of the following would be a suitable
control for this experiment?
A
Repeat the experiment in the same way
but do not incubate the plates.
B
Repeat the experiment in the same way
but incubate at 37 ºC.
C
Set up another plate in the same way but
without the antibiotic disk.
D
Set up another plate in the same way but
without antibiotic in the disk.
[X008/12/02]
Page six
Medium Q
A
General purpose
Synthetic
B
Complex
Differential
C
Differential
General purpose
D
Synthetic
Complex
16. The table below shows some characteristics of
four bacteria species.
Bacteria
Species
Aerobic/
anaerobic
Catalase
reaction
Oxidase
reaction
pH range
for growth
Positive
5 to 9
A
Obligate
aerobe
Positive
B
Obligate
aerobe
Negative
Positive
4 to 8
C
Facultative
anaerobe
Positive
Negative
2 to 5
D
Facultative
anaerobe
Negative
Negative
3 to 7
Which of these bacteria would grow in the
presence of oxygen at pH 4·5 and produce
bubbles of oxygen when tested with hydrogen
peroxide?
17. Which of the following correctly describes
some of the steps involved in enumeration of
bacteriophage?
A
Bacteriophage mixed with bacterial broth
culture, serial dilution of mixture,
dilutions spread on agar plates and
incubated, plaques counted.
B
Serial dilution of bacterial broth culture,
bacteriophage mixed with dilutions,
mixture spread on agar plate and
incubated, colonies counted.
C
Serial dilution of bacteriophage, dilution
mixed with bacterial broth culture,
mixture spread on agar plate and
incubated, plaques counted.
D Bacterial broth culture mixed with
bacteriophage, serial dilution of mixture,
dilutions spread on agar plate and
incubated, colonies counted.
18. The graph below shows the results of an experiment to investigate the effect of different concentrations
of auxins on the development of roots and shoots of plants.
200
shoots
150
Percentage (%)
difference in
length compared
to control plant
100
roots
50
0
50
100
10–6 10–5 10–4 10–3 10–2 10–1
1
10
102
103
Concentration of auxins (ppm)
Which line in the table below shows the effect of auxins at 10–3 ppm?
Roots
Shoots
A
Increased growth
Decreased growth
B
Increased growth
Increased growth
C
Decreased growth
Increased growth
D
Decreased growth
Decreased growth
[X008/12/02]
Page seven
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19.Anaerobic digesters contain biodegradable material such as industrial or domestic waste, and
micro-organisms which break the material down. During this process biogas is produced and the
temperature inside the fermenter increases. Which of the following fermenter designs would be the most
suitable for an anaerobic digester?
A
B
Pressure
gauge
Water
inlet
Water
jacket
Pressure
gauge
Water
jacket
Sparger
C
Water
inlet
D
Water
inlet
Water
jacket
Sparger
Water
inlet
Water
jacket
100
100
80
80
60
60
40
40
20
20
0
Streptomycin
(% maximum concentration)
Bacterial biomass
(% maximum concentration)
20. The graph below shows changes in bacterial biomass and concentration of the antibiotic streptomycin
with time during the growth of Streptomyces bacteria in an industrial fermenter.
Key
Bacterial biomass
Streptomycin
0
0
20
40
60
80
100
120
140
Time (hours)
Which of the following statements is supported by the graph?
A
Streptomycin concentration is at its greatest at 40 hours.
B
Streptomycin is produced during the log phase.
C
Streptomycin is produced during all phases of growth.
D
Streptomycin production is at its maximum after the bacteria has stopped growing actively.
[X008/12/02]
Page eight
21. Which of the following statements about the
immobilisation of enzymes is not true?
A
Immobilisation can improve the stability of enzymes.
B
Immobilisation makes it easier to separate the enzymes from the product.
C Immobilisation of enzymes
effluent disposal problems.
D
decreases
Immobilised enzymes are used mainly for
batch industrial processes.
22. In producing industrial grade alcohol, yeast
cells are immobilised as shown in the diagram
below.
Yeast + Matrix
Immobilised yeast
The type of immobilisation shown in the
diagram is
A
covalent bonding
Bentrapment
Cadsorption
D
non-covalent bonding.
23. Resveratrol is a plant cell metabolite that may have health benefits. A strain of E.coli has been genetically
modified to produce resveratrol using coumaric acid as a substrate.
The graph below shows the concentrations of coumaric acid and resveratrol in the medium containing
the genetically modified E coli.
220
200
180
Coumaric acid
concentration
(mg per litre)
110
100
90
160
140
120
100
80
60
40
20
0
80
70
60 Resveratrol
50 concentration
(mg per litre)
40
30
20
10
0
0
5
10
15
Time (hours)
20
Resveratrol
25
30
Coumaric acid
The rate of resveratrol production between 10 and 20 hours is
A
7·5 mg per hour
B
9·5 mg per hour
C15 mg per hour
D17 mg per hour.
24. Which line in the table below correctly describes the most cost effective separation of cells and alcohol
from the process of alcohol fermentation?
[X008/12/02]
Yeast cells
Alcohol
A
Centrifugation
Precipitation
B
Centrifugation
Distillation
C
Filtration
Precipitation
D
Filtration
Distillation
Page nine
[Turn over
25. The diagram below shows the stages involved in the production of monoclonal antibodies.
Stage 1: Cell fusion
B-lymphocyte
cancer cell
hybrid cell
protein produced
by hybrid cell
Stage 2:
plastic wells
hybrid cell
Stage 3: Cloning of hybrid cells
What is the purpose of Stage 2?
A
To bind antibody to hybrid cells.
B
To select hybrid cells that produce the desired antibody.
C
To remove B-lymphocytes and cancer cells that have not fused.
D
To select hybrid cells that produce the greatest yield of antibody.
26.Hepatitis vaccine can be produced by
genetically engineered yeast cells grown in a
bioreactor.
The following products were
isolated from the growth media of the
bioreactor to produce hepatitis vaccine.
A
are easier to transform
1
Viral surface antigens
B
produce more protein
2
Yeast antigens
C
add sugar residues to proteins
3
Viral DNA
D
grow faster.
Which of these products can be used as a
vaccine against hepatitis?
A
1 only
B
2 only
C
1 and 3 only
D
1, 2 and 3
[X008/12/02]
27. Animal or yeast cells are commonly used
instead of bacteria for the production of human
vaccines because they
Page ten
28. Which of the plasmids shown below could be
used for production of alpha 1 antitrypsin in
the milk of sheep?
A
29. Stem cells are produced by
A embryo cloning for the treatment of
disease
B embryo cloning for
therapeutic proteins
C somatic cell cloning for production of
therapeutic proteins
D somatic cell cloning for the treatment of
disease.
production
of
B
[Turn over
C
D
gene for milk protein
gene for ampicillin resistance
gene for alpha-1 antitrypsin
production
[X008/12/02]
Page eleven
30. Mules are sterile animals so it is not possible to breed them to produce successive generations. Using the
technique of cell cloning, Idaho Gem was the first cloned mule produced.
Some of the steps in cell cloning are shown below.
Nuclear
transfer
Nucleus removed
from adult donor
Transplanted into
uterus of female
Nucleus removed
from egg cell
Which of the following is true of this type of cell cloning?
A
The donor cell is differentiated.
B
The donor cell is undifferentiated.
C
The technique is used to clone embryos.
D
The technique is used to double the reproductive rate.
Candidates are reminded that the answer sheet for Section A MUST be returned
INSIDE the front cover of this answer book.
[X008/12/02]
Page twelve
[Turn over for Section B on Page fourteen
DO NOT WRITE ON THIS PAGE
[X008/12/02]
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SECTION B
All questions in this section should be attempted.
Marks
All answers must be written clearly and legibly in ink.
1. A hospital microbiology department carried out Gram staining of bacteria isolated
from patients. The table below shows the results obtained.
Name of bacterium
Gram stain result
Escherichia coli
Pink
Staphylococcus aureus
Purple
Pseudomonas aeruginosa
Pink
Appearance of bacterium
(a) State the term that describes rod shaped bacteria.
1
(b) Explain why penicillin would be used to treat infections caused by
Staphylococcus rather than Escherichia or Pseudomonas infections.
2
Scientists are continually looking for new methods to treat infectious diseases
caused by bacteria which are resistant to antibiotics.
A protein obtained from the brains of cockroaches has been shown to have an effect
on some bacteria which are antibiotic resistant. Cultures of three different strains
of antibiotic resistant bacteria were incubated with the protein and the percentage
of bacteria killed after 24 hours was measured.
The results are shown in the table below.
Bacteria type
Percentage (%) of bacteria killed after
incubating with the cockroach protein
(24 hours at 37 ºC)
Antibiotic resistant
Escherichia coli
99·6
Antibiotic resistant
Pseudomonas aeruginosa
99·7
Antibiotic resistant
Staphylococcus aureus
97·6
[X008/12/02]
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Marks
1. (continued)
(c)
(i) The original 5 cm3 sample of Staphylococcus aureus contained 2,580,000
bacteria per cm3.
Calculate how many bacteria would be alive at the end of the experiment.
Space for calculation
1
(ii) Apart from incubation time and temperature, state two other factors
that should be kept constant during this experiment.
1
The experiment was repeated using antibiotic resistant Bacillus subtilis, which is a
Gram positive bacteria.
(d) Predict the percentage of antibiotic resistant Bacillus subtilis that would be
killed by the cockroach protein.
%
1
(e) Describe how scientists could determine how many of the original bacteria
were alive at the end of the experiment.
2
[Turn over
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Marks
2. The genes that code for proteins involved in lactose metabolism in E.coli are
grouped together on the bacterial chromosome.
(a) State the term for this arrangement of genes with related functions.
1
(b) One of the genes in this group codes for production of a repressor molecule.
Describe the function of the repressor molecule.
2
Another one of the genes in this group codes for the enzyme ß-galactosidase which
breaks down lactose. Medium containing lactose was inoculated with a culture of
E.coli and the ß-galactosidase activity measured over time. The results are shown
in the graph below.
100
90
ß-galactosidase activity
(% maximum activity)
80
70
60
50
40
30
20
10
0
0
20
40
60
80
100
120
Time after inoculation
(minues)
[X008/12/02]
Page sixteen
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Marks
2. (continued)
(c) Explain the pattern of ß-galactosidase activity shown in the graph.
2
(d) ß-galactosidase also breaks down a substance called X-gal giving a bright blue
product. Explain how X-gal could be used to test if the ß-galactosidase gene
was switched on in E.coli grown on agar plates.
2
[Turn over
[X008/12/02]
Page seventeen
Marks
3. Scientists have identified specific mutations (genetic markers) linked to some types
of cancer. Studying a person’s DNA for these mutations can give information
about the chances of them developing these cancers. This information can
therefore help determine lifestyle changes and possible treatments to increase the
chance of survival.
(a) Genetic markers such as mutations can be identified by using a DNA probe.
State two essential features of a DNA probe.
2
(b) Explain how a substitution mutation can alter the amino acid sequence of a
protein.
2
(c) 1% of Scottish males have the genetic marker for prostate cancer. Use this
information to complete the table below.
All males
Total number in Scotland
2,567,400
Number likely to get prostate
cancer
320,900
Lifetime risk of developing
prostate cancer
1 in 8
Males with genetic marker
12,800
1 in 2
Space for calculation
1
[X008/12/02]
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Marks
3. (continued)
Monoclonal antibodies can be used therapeutically to treat prostate cancer. A drug
has been developed called MMAE which consists of a monoclonal antibody linked
to a drug which selectively kills prostate cancer cells.
(d) Explain how MMAE selectively kills prostate cancer cells.
2
In females, some breast cancer cases have also been linked to genetic markers. A
large number of these mutations have been found in non-coding regions of DNA.
(e) State the term for non-coding regions of DNA in a gene.
1
[Turn over
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Marks
600
Notifications
7000
500
Laboratory
confirmed cases
6000
400
MMR became
available,
1988
5000
MMR 2nd dose
introduced,
1996
300
4000
3000
200
2000
100
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1000
1988
0
Laboratory confirmed cases
Notifications
4. Measles is an illness for which the vaccine MMR is available and is now routinely
given to children. The graph below shows information from an NHS report on
notifications (suspected cases) and confirmed cases of measles in Scotland between
1988–2000.
0
Year
(a) Use information from the graph to explain why the measles MMR vaccination
was introduced into Scottish schools in 1994.
1
A second dose of vaccine was introduced in 1996, as shown in the graph.
(b) State the reason for giving a second dose of vaccine.
1
The fatality (death) rate for measles is highest in children under one year of age.
(c) Explain why children of this age are more vulnerable to measles.
1
(d) “Notifications” are suspected cases which are not confirmed as measles.
How could a laboratory confirm if someone had been exposed to the measles
virus?
1
[X008/12/02]
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4. (continued)
Vaccination provides artificially acquired, active immunity.
(e) Give the meaning of these terms.
Artificially acquired
Active immunity
2
[Turn over
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Marks
5. Apical meristem culture involves removing a small piece of shoot tip (explant) and
growing this to produce new plants. One of the major uses of this technique is to
produce plants which are free of viruses. Some of the steps in the process are
shown in the diagram below.
Adult plant
Stage 1
Stage 2
Stage 3
Stage 4
An experiment was carried out to investigate the effect of explant size on the
number of virus free plants produced, using three different varieties of potato
plants.
The results are shown in the table below.
Variety
Alaska
Spunta
Safrane
Explant size (mm)
at stage 1
Number of explants
at stage 2
Number of plantlets
produced at stage 3
Percentage (%) of
plantlets that are
virus free at stage 3
0·5
90
18
95
1·5
95
45
23
0·5
85
20
90
1·5
99
49
22
0·5
95
20
95
1·5
98
53
28
(a) Explain why the apical meristem of the plant is used for this procedure.
1
(b) For the Alaska variety, calculate the ratio of number of explants at stage 2
and plantlets produced at stage 3 when the explant size was 0·5 mm. Express
your answer as the simplest whole number ratio.
Space for calculation
[X008/12/02]
explants
Page twenty-three
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:
1
plantlets
[Turn over
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Marks
5. (continued)
(c)
(i)Describe the relationship between explant size and percentage of
plantlets that are virus free.
1
(ii) State which variety was most successful in producing virus free plantlets
and explain your answer.
Variety
Explanation
1
In a further experiment using the Safrane variety, the plantlets from stage 3 were
subcultured onto media containing plant growth substances (stage 4). The number
of plants surviving up to 4 weeks after subculture is shown in the graph below.
55
50
1·5 mm explants
45
0·5 mm explants
40
35
Number of
plants
surviving
30
25
20
15
10
5
0
0
[X008/12/02]
1
2
3
4
Time after subculture
(weeks)
5
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5. (continued)
(d)(i)
Using the information from the table and the graph, explain the
difference in survival rate after subculture between the plants from the
1·5 mm and 0·5 mm explants.
1
(ii) Predict what would happen to the number of plants from the 1·5 mm
explants surviving after 6 weeks and justify your answer.
1
Prediction
Justification
1
(e)
(i) State the purpose of including plant growth substances in the medium at
stage 3.
1
(ii) Explain why a carbon source would be required in the growth medium
at stage 2 but not at stage 4.
2
(f) Apart from producing plants which are pathogen free, give one other
advantage of this method of plant production.
1
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Marks
6. A haemocytometer can be used to estimate the number of yeast cells in a culture.
When stained with methylene blue, living yeast cells appear colourless, whereas
dead cells appear blue.
The diagram below shows a sample of a yeast culture in a haemocytometer which
has a depth of 0·2 mm.
0·5 mm
blue cell
colourless cell
0·5 mm
(a) Using the information in the diagram, calculate the total number of cells in
10 mm3 of the culture.
Space for calculation
1
(b)Give one possible source of error in this technique.
1
(c) It was concluded that the culture shown in the diagram was in stationary
phase of growth. Explain why this is a reasonable conclusion.
1
(d) Explain why brewers would be interested in using this technique for
estimating the number of yeast cells.
1
[X008/12/02]
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6. (continued)
When pipetting the yeast sample onto the haemocytometer, a small volume of
culture was spilt on the bench.
(e)
(i) Describe the steps that should be taken to safely deal with the spillage.
2
(ii) State how the used pipette should be disposed of safely.
1
(iii) State the main risk associated with spills of large volumes of liquid
culture.
1
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7. A technician was preparing agar for growing bacterial cultures. He prepared
nutrient agar containing the antibiotic penicillin. He first sterilised the agar, then
added the penicillin.
(a)
(i) Describe the method used to sterilise the nutrient agar before adding the
penicillin.
2
(ii) Describe how the effectiveness of the sterilisation could be checked.
1
(b) Explain why penicillin would be added after sterilisation of the agar.
1
(c) The concentration of the penicillin stock solution was 100 units per cm3.
Calculate the volume of agar and penicillin stock solution that the technician
should use to give a final concentration of 5 units per cm3 in a total volume of
200 cm3 nutrient agar.
Space for calculation
Volume of agar
cm3
Volume of penicillin stock solution
cm3
1
The technician used the agar to prepare slopes for inoculation.
(d) Describe how slopes would be prepared from the molten agar.
1
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8. New breeding techniques are used in agriculture to clone farm animals and to Marks
increase their reproductive rate. The flow diagram below shows some of the steps
taken in one of these techniques.
Fertilised egg collected from cow (mother)
Egg bisected and transplanted into uterus of same cow
(a)
Offspring 1
Offspring 2
(i) Complete the table below by inserting a tick (3) to identify the correct
option(s) in each row.
Identical
Non-identical
Share half genetic
material
Genetic relationship of
mother to offspring
Genetic relationship of
offspring to each other
2
(ii) At what stage is the egg when it is bisected in this technique?
1
(iii) Name the technique shown in the flow diagram.
1
(b)
(i) The fertilised eggs can be genetically modified by inserting foreign genes.
Give one method used to insert foreign genes.
1
(ii)State one advantage that may be gained from inserting foreign genes
into farm animals.
1
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Marks
9. A species of bacteria found in the Antarctic produces protease enzymes. The
protease enzymes can be added to soap powders to digest protein stains in clothes.
Experiments were carried out to investigate the optimum temperature for growth
of the bacteria and activity of the protease enzyme. The bacteria were grown in
fermenters and samples were taken at various time points to determine the cell
number and the enzyme activity in the medium. Absorbance of the samples
measured in a spectrophotometer was used as an indication of cell number. The
bacteria were grown at 4 ºC and 25 ºC.
The results when the bacteria were grown at 4 ºC are shown in the table below.
Time (hours)
Absorbance (units)
Enzyme activity in the medium (units)
0
0·2
0
25
0·3
0
50
1·4
0
75
2·5
0·025
100
3·4
0·150
125
3·5
0·300
150
3·6
0·375
175
3·5
0·375
(a) Draw a line graph to show the absorbance and the enzyme activity in the
medium over 175 hours at 4 ºC. The absorbance and enzyme activity measured
at 25 ºC has already been plotted for you.
(Additional graph paper, if required, can be found on Page thirty-nine.)
4·0
0·40
3·5
0·35
3·0
0·30
2·5
0·25
2·0
0·20
1·5
0·15
1·0
0·10
0·5
0·05
0
Absorbance
at 25 ºC
Enzyme activity
at 25 ºC
Enzyme activity (units)
Absorbance (units)
0
0
25
50
75
100
125
150
175
200
2
Time (hours)
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9. (continued)
(b) The data collected for control samples is not shown. The control samples
contained the same medium but had no bacteria added and were grown at 4 ºC
and 25 ºC. Explain why these are suitable controls.
1
(c) When the samples were taken to determine the bacterial cell number, a
chemical was added to stop the cell growth before they were placed in the
spectrophotometer. Explain why this step was necessary.
1
(d)
(i) What evidence is there from this experiment that the enzyme produced
is extracellular?
1
(ii) Describe how the enzyme could be extracted and purified from the
culture in the fermenter.
2
(e) What evidence is there from the data that this enzyme could be added to
ecologically friendly soap powders that are designed to work at low
temperatures?
1
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10. Many people take supplements of vitamin C, an essential vitamin for humans that
has been shown to have a number of health benefits. Vitamin C is produced
commercially from the sugar sorbitol using various strains of bacteria, such as
Pseudomonas, as shown in the flow diagram below.
Sorbitol
Fermentation by Pseudomonas
Intermediate compound
Chemical reaction
Vitamin C
(a)
(i) Name the process that should be used to provide a constant supply of
the intermediate compound from the bacterial cells.
1
(ii) Describe how this process works.
2
(iii) Other than producing a constant supply, state one advantage of this
process.
1
New strains of bacteria are being developed that can convert the intermediate
compound to vitamin C. Scientists hope to use these bacteria in mixed culture
with the Pseudomonas to carry out the production of vitamin C from sorbitol in a
single fermentation.
(b) Suggest a reason why this might not be possible.
1
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Marks
11. A variety of wheat has been genetically modified to be resistant to the herbicide
glyphosate. As of 2013, field trials have been carried out but this variety of wheat
has not been grown for commercial use. The flow diagram below shows some of
the steps used to genetically modify the wheat.
gene for herbicide resistance
plasmid
gene for antibiotic resistance
plasmid inserted into bacteria
bacteria incubated with plant cells
plant cells cultured in laboratory
Petri dish containing
selection medium
herbicide resistant plantlets
plantlets planted out for field trials
(a) Complete the following sentences by underlining one of the options in bold in
each pair.
{
The plant cells used in this process are called
a
The enzyme used to remove the structure is
{
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cell wall
cell membrane
}
chloroplasts
which lack
protoplasts
}
.
{
}
cellulase
.
pectinase
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11. (continued)
The following ingredients were used to make 1 litre of plant tissue culture medium.
30 g sucrose
10 g agar
4 g M and S salts
2 g antibiotic
(b)
(i) Explain how the presence of antibiotic in the medium selects for plants
expressing herbicide resistant genes.
2
(ii) 20 cm3 of medium is required for each petri dish.
Calculate how many petri dishes of medium could be made from 1 litre.
Space for calculation
1
(c) Explain how placing a gene for herbicide resistance in the genome of the plant
enables it to grow in the presence of the herbicide glyphosate.
1
(d) Suggest an environmental reason why these genetically modified wheat plants
have not gone past the field trial stage.
1
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SECTION C
Both questions in this section should be attempted.
Note that each question contains a choice.
Questions 1 and 2 should be attempted on the blank pages which follow.
All answers must be written clearly and legibly in ink.
Supplementary sheets, if required, may be obtained from the Invigilator.
Labelled diagrams may be used where appropriate.
1.Answer either A or B.
A. Give an account of commercial cell culture production under the following
headings:
(a)
Laboratory models;
 5
(b)
Scaling up.
 5
(10)
OR
B. Give an account of forensic and environmental biotechnology applications
under the following headings:
(a)
DNA profiling;
 5
(b)
Biosensors and bioremediation.
 5
(10)
In Question 2 ONE mark is available for coherence and ONE mark is available
for relevance.
2.Answer either A or B.
A. Prokaryotes and eukaryotes have different cellular structures. Discuss the
functions of the structures found in these cells.
(10)
OR
B. Yeast are facultative anaerobes. Discuss energy production in yeast in the
presence and absence of oxygen.
[END OF QUESTION PAPER]
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4·0
0·40
3·5
0·35
3·0
0·30
2·5
0·25
2·0
0·20
1·5
0·15
1·0
0·10
0·5
0·05
0
0
0
25
50
75
100
125
150
175
200
Time (hours)
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Absorbance
at 25 ºC
Enzyme activity
at 25 ºC
Enzyme activity (units)
Absorbance (units)
ADDITIONAL GRAPH PAPER FOR USE IN QUESTION 9(a)
ACKNOWLEDGEMENTS
Section A Question 30 – Photograph of Idaho Gem is taken from the article “The latter
day saint who cloned a mule” from www.meridianmagazine.com.
SQA has made every effort to trace the owners of copyright materials
reproduced in this question paper, and seek permissions. We will be happy to
incorporate any missing acknowledgements. Please contact Janine.Anderson@
sqa.org.uk.
Section B Question 8(i) – Catherine 311/shutterstock.com
Section B Question 8(ii) – Anatoliy Lukich/shutterstock.com