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B & C
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Day Month Year Number of seat Scottish candidate number
HTP
X008/12/02
*X008/12/02* ©
BIOTECHNOLOGY HIGHER
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.
2 The 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.
3 Additional 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.
5 Rough 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.
6 Before 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.
Full name of centre Town
Forename(s) Surname
Date of birth
N A T I O N A LQ U A L I F I C A T I O N S2 0 1 5
T H U R S D A Y , 2 1 m A Y1 . 0 0 P m – 3 . 3 0 P m
SECTION A
Read carefully
1 Check that the answer sheet provided is for Biotechnology Higher (Section A).
2 For this section of the examination you must use an HB pencil and, where necessary, an eraser.
3 Check 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.
4 If any of this information is wrong, tell the Invigilator immediately.
5 If this information is correct, print your name and seat number in the boxes provided.
6 The 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).
7 There is only one correct answer to each question.
8 Any rough working should be done on the question paper or the rough working sheet, not on your answer sheet.
9 At 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?
A Mixed
B Pure
C Simple
D Complex
The correct answer is A—Mixed. The answer A has been clearly marked in pencil with a horizontal line (see below).
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 B C D
A B C D
Page two[X008/12/02]
SECTION A
All questions in this Section should be attempted.
Answers should be given on the separate answer sheet provided.
Page three[X008/12/02]
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.
2. Which of the following structures is produced only during sexual reproduction in Mucor?
A Mycelium
B Sporangium
C Zygospore
D Multinucleate hyphae
3. The diagram below shows a fungal growth curve.
Cell number
Time
A
B
C
D
Section D of the curve is described as
A latent phase
B senescent phase
C exponential phase
D lag phase.
4. Which of the following diagrams represents the structure of a virus?
DNA
DNA
RNA
DNA
DNA
membrane
envelope
RNA
capsid
capsid
capsid
capsid
A
B
C
D
[Turn over
Page four[X008/12/02]
7. Which of the following statements describes fermentation?
A Aerobic growth of yeast
B Anaerobic growth of yeast
C Anaerobic growth of micro-organisms
D Aerobic and anaerobic growth of micro-organisms
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.
Which of the following statements explains these observations?
A Delayed binary fission, leading to more daughter cells.
B Earlier binary fission, leading to more daughter cells.
C Delayed binary fission, leading to larger daughter cells.
D Earlier binary fission, leading to larger daughter cells.
6. The graph below shows the effect of temperature on the mean generation time of three different bacteria species (P, Q and R).
Temperature (ºC)
Mea
n g
ener
atio
n t
ime
(min
ute
s) 120
90
R
Q
P
60
30
020 25 30 35 40
The number of generations per hour for species P at 30 ºC is
A 0·75
B 1
C 1·33
D 2.
Page five[X008/12/02] [Turn over
11. A suitable control for an experiment to transform E.coli would contain
A E.coli, plasmid and media containing antibiotic
B E.coli, and media containing antibiotic
C E.coli, plasmid and media without antibiotic
D E.coli, and media without antibiotic.
12. T lymphocytes mediate an immune response by
A activating macrophages to kill micro-organisms
B producing antibodies to attack micro-oganisms
C activating lysosomes to kill micro-organisms
D producing enzymes to attack micro-organisms.
9. Heat can be used to separate the DNA strands in a double helix.
Increasing temperature separates the strands of DNA by
A breaking down bases
B breaking hydrogen bonds
C breaking down nucleotides
D breaking sugar-phosphate bonds.
10. Which of the following can be used as cloning vectors?
A Viruses
B Protoplasts
C Yeast
D Bacteria
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?
Sal I
Sal I
Sal I
Hpa I
Hpa I
EcoR I
EcoR I
EcoR I
Sal I
Hpa I
Hpa I
Sal I
EcoR I
EcoR I
EcoR I
Sal I
A
B
C
D
Page six[X008/12/02]
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
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.
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 Medium Q
A General purpose Synthetic
B Complex Differential
C Differential General purpose
D Synthetic Complex
13. Which line in the table below correctly identifies the type of risk assessment and its description?
Simple Generic Novel
AFrom first principles Familiar hazard, well known
control measuresUses authoritative code of practice
BFamiliar hazard, well known control measures
Uses authoritative code of practice
From first principles
CFamiliar hazard, well known control measures
From first principles Uses authoritative code of practice
DFrom first principles Uses authoritative code of
practiceFamiliar hazard, well known control measures
16. The table below shows some characteristics of four bacteria species.
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.
roots
shoots
Percentage (%) difference in
length compared to control plant
200
150
100
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
Page seven[X008/12/02] [Turn over
Bacteria Species
Aerobic/anaerobic
Catalase reaction
Oxidase reaction
pH range for growth
AObligateaerobe
Positive Positive 5 to 9
BObligateaerobe
Negative Positive 4 to 8
CFacultativeanaerobe
Positive Negative 2 to 5
DFacultativeanaerobe
Negative Negative 3 to 7
Page eight[X008/12/02]
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?
Pressure gauge
Water jacket
Water inlet
Pressure gauge
Water jacket
Water inlet
Sparger
Water jacket
Water inlet Water
jacket
Water inlet
A B
C D
Sparger
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.
Bac
teri
al b
iom
ass
(% m
axim
um
con
cen
trat
ion
)
Str
epto
myc
in(%
max
imu
m c
once
ntr
atio
n)
Key
Bacterial biomass
Streptomycin
Time (hours)
100 100
80 80
60 60
40 40
20 20
0 00 20 40 60 80 100 120 140
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.
Page nine[X008/12/02]
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 decreases effluent disposal problems.
D 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
B entrapment
C adsorption
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.
220 110
200 100
180 90
160 80
140 70
120 60
100 50
80 40
60 30
40 20
20 10
0 00 5 10 15 20 25 30
Time (hours)
Resveratrol Coumaric acid
Resveratrolconcentration(mg per litre)
Coumaric acidconcentration(mg per litre)
The rate of resveratrol production between 10 and 20 hours is
A 7·5 mg per hour
B 9·5 mg per hour
C 15 mg per hour
D 17 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?
Yeast cells Alcohol
A Centrifugation Precipitation
B Centrifugation Distillation
C Filtration Precipitation
D Filtration Distillation
[Turn over
25. The diagram below shows the stages involved in the production of monoclonal antibodies.
Stage 1: Cell fusion
Stage 2:
Stage 3: Cloning of hybrid cells
B-lymphocyte cancer cell
hybrid cell
hybrid cell
plastic wells
protein produced by hybrid cell
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.
Page ten[X008/12/02]
27. Animal or yeast cells are commonly used instead of bacteria for the production of human vaccines because they
A are easier to transform
B produce more protein
C add sugar residues to proteins
D grow faster.
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.
1 Viral surface antigens
2 Yeast antigens
3 Viral DNA
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
Page eleven[X008/12/02]
29. Stem cells are produced by
A embryo cloning for the treatment of disease
B embryo cloning for production of therapeutic proteins
C somatic cell cloning for production of therapeutic proteins
D somatic cell cloning for the treatment of disease.
[Turn over
28. Which of the plasmids shown below could be used for production of alpha 1 antitrypsin in the milk of sheep?
A
B
C
D
gene for milk protein
gene for ampicillin resistance
gene for alpha-1 antitrypsin production
Page twelve[X008/12/02]
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.
Nucleus removed from adult donor
Nucleus removed from egg cell
Transplanted into uterus of female
Nuclear transfer
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.
Page thirteen[X008/12/02]
[Turn over for Section B on Page fourteen
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SECTION B
All questions in this section should be attempted.
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 Appearance of bacterium
Escherichia coli Pink
Staphylococcus aureus Purple
Pseudomonas aeruginosa Pink
(a) State the term that describes rod shaped bacteria.
(b) Explain why penicillin would be used to treat infections caused by Staphylococcus rather than Escherichia or Pseudomonas infections.
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 resistantEscherichia coli
99·6
Antibiotic resistantPseudomonas aeruginosa
99·7
Antibiotic resistantStaphylococcus aureus
97·6
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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
(ii) Apart from incubation time and temperature, state two other factors that should be kept constant during this experiment.
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.
%
(e) Describe how scientists could determine how many of the original bacteria were alive at the end of the experiment.
[Turn over
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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.
(b) One of the genes in this group codes for production of a repressor molecule. Describe the function of the repressor molecule.
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.
Time after inoculation(minues)
ß-g
alac
tosi
das
e ac
tivi
ty(%
max
imu
m a
ctiv
ity)
100
90
80
70
60
50
40
30
20
10
00 20 40 60 80 100 120 140
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2. (continued)
(c) Explain the pattern of ß-galactosidase activity shown in the graph.
(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.
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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.
(b) Explain how a substitution mutation can alter the amino acid sequence of a protein.
(c) 1% of Scottish males have the genetic marker for prostate cancer. Use this information to complete the table below.
All males Males with genetic marker
Total number in Scotland 2,567,400
Number likely to get prostate cancer
320,900 12,800
Lifetime risk of developing prostate cancer
1 in 8 1 in 2
Space for calculation
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Page nineteen
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.
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.
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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.
600 7000
500 6000
4005000
3004000
200
3000
100
2000
0
1000
0
Not
ific
atio
ns
Lab
orat
ory
con
firm
ed c
ases
Notifications
Laboratoryconfirmed cases
MMR became available, 1988
MMR 2nd dose introduced,1996
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
Year
(a) Use information from the graph to explain why the measles MMR vaccination was introduced into Scottish schools in 1994.
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.
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.
(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?
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4. (continued)
Vaccination provides artificially acquired, active immunity.
(e) Give the meaning of these terms.
Artificially acquired
Active immunity
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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 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
Alaska0·5 90 18 95
1·5 95 45 23
Spunta0·5 85 20 90
1·5 99 49 22
Safrane0·5 95 20 95
1·5 98 53 28
(a) Explain why the apical meristem of the plant is used for this procedure.
(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
: explants : plantlets
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[X008/12/02] Page twenty-four
5. (continued)
(c) (i) Describe the relationship between explant size and percentage of plantlets that are virus free.
(ii) State which variety was most successful in producing virus free plantlets and explain your answer.
Variety
Explanation
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
45
40
35
30
25
20
15
10
5
00 1 2 3 4 5
Time after subculture (weeks)
Number of plants surviving
1·5 mm explants
0·5 mm explants
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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.
(ii) Predict what would happen to the number of plants from the 1·5 mm explants surviving after 6 weeks and justify your answer.
Prediction
Justification
(e) (i) State the purpose of including plant growth substances in the medium at stage 3.
(ii) Explain why a carbon source would be required in the growth medium at stage 2 but not at stage 4.
(f) Apart from producing plants which are pathogen free, give one other advantage of this method of plant production.
[Turn over
[X008/12/02] Page twenty-six
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.
blue cell
colourless cell
0·5 mm
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
(b) Give one possible source of error in this technique.
(c) It was concluded that the culture shown in the diagram was in stationary phase of growth. Explain why this is a reasonable conclusion.
(d) Explain why brewers would be interested in using this technique for estimating the number of yeast cells.
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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.
(ii) State how the used pipette should be disposed of safely.
(iii) State the main risk associated with spills of large volumes of liquid culture.
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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.
(ii) Describe how the effectiveness of the sterilisation could be checked.
(b) Explain why penicillin would be added after sterilisation of the agar.
(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
The technician used the agar to prepare slopes for inoculation.
(d) Describe how slopes would be prepared from the molten agar.
[X008/12/02]
8. New breeding techniques are used in agriculture to clone farm animals and to 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
Offspring 1 Offspring 2
(a) (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
(ii) At what stage is the egg when it is bisected in this technique?
(iii) Name the technique shown in the flow diagram.
(b) (i) The fertilised eggs can be genetically modified by inserting foreign genes.
Give one method used to insert foreign genes.
(ii) State one advantage that may be gained from inserting foreign genes into farm animals.
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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.)
0 00 25 50 75 100 125 150 175 200
Time (hours)
2·0 0·20
1·5 0·15
1·0 0·10
0·5 0·05
4·0 0·40
3·5 0·35
3·0 0·30
2·5 0·25
Ab
sorb
ance
(u
nit
s)
En
zym
e ac
tivi
ty (
un
its)
Absorbanceat 25 ºC
Enzyme activityat 25 ºC
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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.
(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.
(d) (i) What evidence is there from this experiment that the enzyme produced is extracellular?
(ii) Describe how the enzyme could be extracted and purified from the culture in the fermenter.
(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?
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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
Intermediate compound
Vitamin C
Fermentation by Pseudomonas
Chemical reaction
(a) (i) Name the process that should be used to provide a constant supply of the intermediate compound from the bacterial cells.
(ii) Describe how this process works.
(iii) Other than producing a constant supply, state one advantage of this process.
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.
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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
gene for antibiotic resistance
plasmid
plasmid inserted into bacteria
bacteria incubated with plant cells
plant cells cultured in laboratory
plantlets planted out for field trials
Petri dish containing selection medium
herbicide resistant plantlets
(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{chloroplasts protoplasts }which lack
a{cell wall cell membrane }.
The enzyme used to remove the structure is{cellulase pectinase}.
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11. (continued)
The following ingredients were used to make 1 litre of plant tissue culture medium.
30 g sucrose10 g agar
4 g M and S salts2 g antibiotic
(b) (i) Explain how the presence of antibiotic in the medium selects for plants expressing herbicide resistant genes.
(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
(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.
(d) Suggest an environmental reason why these genetically modified wheat plants have not gone past the field trial stage.
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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;
(b) Scaling up.
OR
B. Give an account of forensic and environmental biotechnology applications under the following headings:
(a) DNA profiling;
(b) Biosensors and bioremediation.
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.
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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ADDITIONAL GRAPH PAPER FOR USE IN QUESTION 9(a)
0 00 25 50 75 100 125 150 175 200
Time (hours)
2·0 0·20
1·5 0·15
1·0 0·10
0·5 0·05
4·0 0·40
3·5 0·35
3·0 0·30
2·5 0·25
Ab
sorb
ance
(u
nit
s)
En
zym
e ac
tivi
ty (
un
its)
Absorbanceat 25 ºC
Enzyme activityat 25 ºC
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 [email protected].
Section B Question 8(i) – Catherine 311/shutterstock.com
Section B Question 8(ii) – Anatoliy Lukich/shutterstock.com
