2005 Biotechnology
Higher
Finalised Marking Instructions
These Marking Instructions have been prepared by Examination Teams
for use by SQA Appointed Markers when marking External Course
Assessments.
GENERAL MARKING ADVICE: BIOTECHNOLOGY
The marking schemes are written to assist in determining the 'minimal acceptable answer' rather than
listing every possible correct and incorrect answer. The following notes are offered to support
Markers in making judgements on candidates' evidence, and apply to marking both end of unit
assessments and course assessments.
1.
There are no half marks. Where three answers are needed for two marks, normally one or two
correct answers gain one mark.
2.
In the mark scheme, if a word is underlined then it is essential; if a word is (bracketed) then it
is not essential.
3.
In the mark scheme, words separated by / are alternatives.
4.
There are occasions where the second answer negates the first and no marks are given. There is
no hard and fast rule here, and professional judgement must be applied. Good marking
schemes should cover these eventualities.
5.
Where questions on data are in two parts, if the second part of the question is correct in relation
to an incorrect answer given in the first part, then the mark can often be given. The general rule
is that candidates should not be penalised repeatedly.
6.
If a numerical answer is required and units are not given in the stem of the question or in the
answer space, candidates must supply the units to gain the mark. If units are required on more
than one occasion, candidates should not be penalised repeatedly.
7.
Clear indication of understanding is what is required, so:
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8.
if a description or explanation is asked for, a one word answer is not acceptable
if the questions ask for letters and the candidate gives words and they are correct, then
give the mark
if the question asks for a word to be underlined and the candidate circles the word, then
give the mark
if the result of a calculation is in the space provided and not entered into a table and is
clearly the answer, then give the mark
chemical formulae are acceptable eg CO2, H2O
contractions used in the Arrangements document eg DNA, ATP are acceptable
words not required in the syllabus can still be given credit if used appropriately eg
metaphase of meiosis
Incorrect spelling is given. Sound out the word(s),
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•
•
if the correct item is recognisable then give the mark
if the word can easily be confused with another biological term then do not give the mark
eg ureter and urethra
if the word is a mixture of other biological words then do not give the mark, eg mellum,
melebrum, amniosynthesis.
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9.
Presentation of Data:
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if a candidate provides two graphs or bar charts (eg one in the question and another at the
end of the booklet), mark both and give the higher score
if the question asks for a line graph and a histogram or bar chart is given, then do not give
the mark(s). Credit can be given for labelling the axes correctly, plotting the points,
joining the points either with straight lines or curves (best fit is rarely used)
if the x and y data are transposed, then do not give the mark
if the graph used less than 50% of the axes, then do not give the mark
if 0 is plotted when no data is given, then do not give the mark (ie candidates should only
plot the data given)
no distinction is made between bar charts and histograms for marking purposes. (For
information: bar charts should be used to show discontinuous features, have descriptions
on the x axis and have separate columns; histograms should be used to show continuous
features; have ranges of numbers on the x axis and have contiguous columns.)
where data is read off a graph it is often good practice to allow for acceptable minor error.
An answer may be given 7.3 + 0.1.
10.
Extended response questions: if a candidate gives two answers where there is a choice, mark
both and give the higher score.
11.
Annotating scripts:
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12.
put a 0 is the box if no marks awarded – a mark is required in each box
indicate on the scripts why marks were given for part of a question worth 3 or 2 marks. A
or near answers will do.
Totalling scripts: errors in totalling can be more significant than errors in marking:
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enter a correct and carefully checked total for each candidate
do not use running totals as these have repeatedly been shown to lead to more errors.
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2005 Biotechnology Higher
Marking scheme
Section A
1.
A
16.
C
2.
D
17.
A
3.
A
18.
A
4.
B
19.
D
5.
B
20.
C
6.
C
21.
B
7.
D
22.
A
8.
D
23.
B
9.
A
24.
A
10.
B
25.
C
11.
C
26.
B
12.
C
27.
A
13.
A
28.
D
14.
D
29.
B
15.
C
30.
B
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Marking Instructions
Biotechnology Higher
Section B & C
Question
1
(a)
Acceptable Answer
(i)
(ii)
(b)
(c)
(i)
(ii)
Feature of the fermenter
Mark
Unacceptable Answer
Function
Water jacket
Regulates temperature
Safety valve
Protects against over
pressurisation /
Releases excess
pressure
Sparger
Adds air
1 mark for 2 names
1 mark for function
2
(Addition of) pressurised steam
1
Cost/technical specification/containment of microorganisms/control systems or any suitable answer
1
Contaminating micro-organisms/bacteria
competes for growth
present
that
1
Nutrients in the medium denatured/destroyed
1
Page 5
Steam
Negates
Question
2
Acceptable Answer
Mark
(a)
Description of gene
mutation
A nuleotide is replaced
by another
A nuleotide is added to
the sequence of DNA
The order of two
nucleotides is reversed
Name of gene mutation
substitution
insertion
inversion
3 correct = 2 marks
2/1 correct = 1 mark
1.
(b)
2.
3.
Every codon after the mutation point is changed/
frameshift
All amino acids after the mutation point are changed
Tertiary structure/shape is changed/in correct folding
Any 2 point = 2 marks
(c)
2
2
(i)
Peptide bond
1
(ii)
Hydrogen bond
1
Page 6
Unacceptable Answer
Negates
Question
3
Acceptable Answer
Mark
(a)
(DNA) ligase
1
(b)
Inducer
1
(c)
Only bacteria transformed with plasmid will grow on the
selective medium/medium with antibiotic/ampicillin
1
1.
(d)
2.
3.
Regulator gene produces repressor protein/
substance W
Repressor protein binds to the operator
Gene Z/structural gene cannot be transcribed/is
switched off
3 points = 2 marks
2/1 points = 1 mark
4
November
1
(i)
1.
2.
1
1
(ii)
The number of cases for the under 20s falls below that of the
over 20s
(a)
(b)
(c)
2
1.
2.
3.
Number of cases higher for under 20s
Peaks and troughs coincide
Antigen stimulates (B) lymphocytes to produce
antibodies/humoral response
Some immune cells remain in the blood on the look
out for antigen/memory cells produced
Faster/greater production of antibodies on second
exposure
Any 2 = 2 marks
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1
2
Unacceptable Answer
Negates
Question
(d)
Acceptable Answer
Description
Naturally
acquired
Antibodies in
breast milk
protect the
baby
Antibodies
from a horse
are injected
into a human
infected with
tetanus
A bacterial
infection
stimulates the
production of
antibodies
5
Types of immunity
Artificially
Passive
acquired
Active
Mark
1 mark for each correct line
3
(a)
Substance X:
Process Y:
1
1
(b)
The higher the metabolic activity, the more cristae/folds
observed (or vice versa)
CO2
Krebs cycle/TCA cycle/citric acid cycle
1
(c)
4 /more ATP molecules are produced and 2 /fewer ATPs are
used up
1
(d)
1800%
1
Page 8
Unacceptable Answer
Negates
Question
(e)
Acceptable Answer
Mark
Prediction:
Glucose consumption will decrease
Justification:
Yeast cell needs to breakdown less glucose
to gain same energy
1 mark for prediction
1 mark for justification
6
(a)
2
(c)
(d)
Temperature, dilution of bacteria
Type of Agar/size of disc/antibiotic concentration/volume of
antibiotic/time of incubation/pH of medium/nutrient
concentration/strain of micro-organism/any other reasonable
answer
1 mark per variable
(b)
2
Micro-organism:
S aureus
Reason:
Shortest streak/growth starts
furthest from the disc/growth most
restricted
1
Result:
Gram positive/purple
1
Explanation:
Penicillin more active against gram
positives. Penicillin more active
against cells with high content of
peptidoglycen in cell wall/S aureus
most sensitive to penicilin
1.
2.
Unacceptable Answer
Pour (freshly made) disinfectant (around) and over
the spillage
Autoclave debris
Page 9
Less growth
1
2
Negates
Question
7
Acceptable Answer
Mark
(a)
1.75 x 106 cells per cm3
1
(b)
Count more than 1 square/repeat with another sample and
obtain an average
1
(c)
To provide a more accurate estimate/count
1
(d)
Haemocytometer:
total count/dead and live/viable
and non viable
Colonies counted
on plate:
viable/live cells
1 mark for haemocytometer
1 mark for plate count
8
2
(a)
M luteus
1
(b)
S pyogenes
1
(c)
Name:
C tetani
Explanation:
C tetani produces spores that resist high
temperatures
1 mark for name
1 mark for explanation
(d)
Hydrogen peroxide
2
1
Page 10
Unacceptable Answer
Negates
Question
9
Acceptable Answer
Mark
(a)
1.05 million cells per cm3
1
(b)
1.1 million cells per cm3
1
(c)
4 total cells: 1 viable cell
1
(d)
As number of viable cells increase, concentration of glucose
decreases
1
Glucose decreases from 4.4 to 2.5 at day 4. Viable cells
increases from 0.2 to 1.5 at day 4
1
(e)
3.75 µg per cm3
1
(f)
90 µg per million viable cells
1
Page 11
Unacceptable Answer
Negates
Question
10
Acceptable Answer
Mark
Different micro-organisms show different growth
characteristics
1
(b)
To solidify/set the media
1
(c)
Bile salts only allow growth of intestinal bacteria/Bile salts
prevents the growth of other bacteria
1
(d)
Look for red colonies
1
(e)
Dry/flat/smooth/not contaminated/correct depth/no
condensation/no air bubbles/level evenly covered
(a)
2 features = 1 mark
11
1
(a)
(Crystalline) protein
1
(b)
Agrobacterium (tumefaciens)
1
(c)
Plants are not eaten by (gypsy moth) caterpillars/(gypsy
moth) caterpillars are killed by Bt toxin/modified plants are
insect/pest resistant
1
Page 12
Unacceptable Answer
Negates
Question
12
(a)
Mark
(i)
To separate protein/liquid from (E.coli) cells
1
(ii)
Charge/shape
1
(iii)
Extracting cells from liquid culture
1
Peak for interferon is separate/does not overlap/from other
peaks, so there is no contamination from other proteins
1
(b)
13
Acceptable Answer
Enzyme can be recycled/easier separation of enzyme and
product/increased stability/decrease effluent/enzyme does
not need to be recovered from the product/cheaper
(a)
Any 2 for 2 marks
(b)
Unacceptable Answer
2
To ensure the enzyme was working before immobilisation/
at the start
1
(ii)
To prevent the enzyme being denatured
1
(iii)
To remove unimmobilised enzyme
1
(iv)
Use agarose slices with no enzyme/denatured enzyme/water
1
(i)
Page 13
Removal of contaminants
Negates
(c)
(i)
Acceptable Answer
ß galactosidase activity as a% of the initial activity
Question
Mark
100
80
AGAROSE
60
40
20
0
ALGINATE
1
2
3
4
5
6
7
Time (days)
1 mark for: labelling and scaling of y-axis and labelling
and scaling of x-axis
1 mark for plotting agarose
1 mark for plotting alginate
(ii)
(iii)
3
Enzyme is more stable when immobilised in
agarose/enzyme immobilised in agarose maintains activity
longer/loses less activity
1
The initial activities may be different/valid comparisons can
be made
1
Page 14
Unacceptable Answer
Negates
Section C
1.
A.
(a)
Function of organelles
1.
2.
3.
4.
5.
6.
nucleus for storage of chromosomes/DNA/genetic material
mitochondria for aerobic respiration
rough endoplasmic reticulum for protein transport
golgi apparatus for protein modification/packaging
lyosomes contain digestive enzymes
ribosomes for protein synthesis
max 4 of 6 points
(b)
4
Structure of yeast and Mucor
7.
8.
9.
yeast are unicellular
Mucor has multinucleate cytoplasm
Mucor has hyphae
max 2 of 3 points
(c)
2
Reproduction of fungi
10.
11.
12.
13.
14.
15.
asexual and sexual reproduction
budding
spore formation
spores in sporangia
zygospore formation
conjugation
max 4 of 6 points
B.
(a)
4
DNA structure
1.
2.
3.
4.
5.
6.
7.
8.
double helix
composed of nucleotides
composed of deoxyribose sugar, phosphate and base
complementary base pairing
A with T and C with G OR names (once only)
(weak) hydrogen bonds between bases/strands
antiparallel strands OR 3’ opposite 5’ end
presence of exons and introns
5 marks maximum from 1 to 8
Page 15
5
(b)
DNA replication
9.
10.
11.
12.
13.
14.
15.
16.
DNA/helix untwists/unwinds
DNA unzips/hydrogen bonds between bases are broken
enzymes and ATP needed
free DNA nucleotides pair with exposed/complementary bases, A
with T and C with G (once only)
adjacent nucleotides bonded phosphate to deoxyribose sugar/sugar
phosphate “backbone” formed
polymerase enzyme joins nucleotides
nucleotides added to 3’ end (only)
two identical DNA molecules produced/semi-conservative
5 marks maximum from 9 to 16
2.
5
Answer either A or B
A.
1.
2.
3.
4.
5.
6.
7.
8.
egg taken from donor
embryo grown to blastocyst stage
undifferentiated cells isolated
nuclei removed from undifferentiated cells
nuclei removed from donor egg cells
nuclei from undifferentiated cells injected into enucleated donor egg cells
cells cultured to blastocyst stage
transplanted into surrogate mother/used to produce stem cells
Ethical issues
9.
10.
11.
12.
no benefit to surrogate mother
original embryo is killed
low survival rates
appropriate other issue eg tampering with life
max 6 marks from points 1-8 and max 2 marks from points 9-12
10
+ 1 mark for relevance
+ 1 mark for coherence
Relevance
1. Must not give irrelevant details (eg somatic cell cloning)
2. Must have given 4 minimum relevant facts
Both must apply correctly to gain the relevance mark.
Coherence
1. Writing should be under sub-headings or divided into paragraphs
2. Related information should be grouped together and at least 3 marks from
1-8 and at least 2 marks from 9–12
3. The account should be presented in a logical and progressive way
Any two of these three points applied correctly gains the coherence mark
Page 16
B.
Process
1.
2.
3.
4.
the required gene is inserted by microinjection/or by viral infection
gene is inserted into a fertilised egg
gene is inserted close to the gene that codes for milk
protein is secreted in the animal’s milk
Advantages
5.
6.
7.
8.
9.
no need for (large scale) fermentation vessels
no need for continuous monitoring of growth conditions
no need for maintenance of sterile conditions
animals can add sugar residues to proteins/process and package eukaryotic
protein
ability to secrete protein can be passed from generation to generation
Disadvantages
10.
11.
12.
low success rate
animal could die before breeding
only female animals produce milk
max 3 marks for points 1-4
max 3 marks from points 5-9
max 2 marks from points 10-12
+ 1 mark for relevance
+ 1 mark for coherence
Relevance
1. Must not give irrelevant details
2. Must have given 4 minimum relevant facts
Both must apply correctly to gain the relevance mark.
Coherence
1. Writing should be under sub-headings or divided into paragraphs
2. Related information should be grouped together and at least 2 marks for
points 1-4, 2 marks for points 5-9 and 1 mark for 10–12
3. The account should be presented in a logical and progressive way
Any two of these three points applied correctly gains the coherence mark
[END OF MARKING INSTRUCTIONS]
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