Download SECTION8PRACTICALANDDATASKILLS ms

Feversham College
A-level Biology (7401/7402)
Name:
Class:
Section 8 Practical Skills
Author:
Date:
Time:
Marks:
Comments:
Page 1
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M1.(a)
(i)
1.
Sex;
2.
Lifestyle;
Stress, smoking, diet etc are examples of lifestyle.
3.
Body mass;
3. Allow weight for mark point 3.
4.
Health;
Reject: height.
5.
Ethnicity;
6.
Genetic factors / family history;
2 max
(ii)
1.
Large sample / number / 410 000;
Reject: random
2.
Long time period / 8.5 / many years;
3.
Different countries / more than one country;
2
(b)
Correct answer of 209 / 209.1 = 2 marks;
Answer of 210 = one mark
Incorrect answer but multiplies by 8.5 = 1 mark;
2
(c)
Age affects risk of cancer;
Must relate to cancer not just to illness
1
(d)
1.
Correlation does not mean causal relationship;
1. Reject casual for point 1.
Reference to 'due to other factors' on its own is not enough for
a mark
2.
Tea / coffee contains other substances / different amounts of caffeine /
estimated intake (of tea / coffee);
3.
No control group;
4.
Only one type of cancer studied / further studies required / only one
investigation / study / group;
4
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(e)
(i)
1.
Treated the same;
2. Accept decaffeinated
2.
No caffeine;
2. Reject placebo.
2
(ii)
1.
Absorb different amounts;
Reject: Different body masses
2.
Broken down by enzymes / digested;
3.
Different blood volumes;
4.
Differences in metabolism;
5.
Caffeine from a different source;
1 max
(iii)
1.
Less oxygen / glucose to (cancer) cells;
'Reduces cell division' on its own should not be credited.
2.
Less carcinogens;
3.
Reduces spread of cancer (cells);
1 max
[15]
M2.
(a)
Endonuclease / restriction enzyme;
1
(b)
DNA made of base pairs;
Each base pair is same length / occupies same distance
along backbone;
2
(c)
(i)
Second blank box from left labelled 6;
1
(ii)
Distance moved depends on length / number of base pairs /
second longest fragment / second shortest distance identified;
1
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(d)
5;
1
[6]
M3.
(a)
mass of undifferentiated / unspecialised / totipotent cells;
uncontrolled cell division;
(not ‘repeated’)
metastasis / (cells break off and) form new tumours /
spread to other parts of body;
3
(b)
cancer takes time to develop / exposure when young but cancer
triggered later; other organs destroyed before death occurs /
metastasis affects other organs;
immune system less effective in old people;
longer time of exposure to UV / accumulation of mutagenic effect;
1 max
(c)
dark skin / melanin / pigment stops UV light / prevents burning;
so less cancer risk in dark skinned people / less likely to develop tumours;
(allow converse)
2
[6]
M4.
(a)
No cadmium;Other conditions same as cadmium-treated group;
2
(b)
(i)
As a measure of the effect due to cadmium /
to make a comparison;
1
(ii)
Becoming more methylated;
Ignore later slight decrease/no change
1
(iii)
Production of more methyltransferase enzyme /
increased activity of transferase;
Extra incorrect relevant information - cancel
1
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(c)
RNA-polymerase could not bind (to DNA / to promoter);mRNA of p16 could not be
made / no transcription of p16 gene;
2
(d)
Any four from:1. Cadmium causes expression of methyltransferase gene /
increased activity transferase (from 2 to 3 weeks in);2. Methyl groups on to
promoter / p16 gene / suppressor (gene);3. (p16) normally suppresses tumour
growth;4. p16 protein / p16 expression falls after 4 weeks / after
methylation;5. Tumour formation occurs (after 10 weeks) after p16 falls /
after suppressor gene activity falls;
4 max
[11]
M5.(a)
1.
Carriers are heterozygous / have one normal copy and one mutant copy of gene /
have one recessive allele / don't have the condition;
2.
Both have DNA that binds (about) half / 50% amount of probe (that
non-carrier does);
3.
Probe binds to dominant / healthy allele so only one copy of exon in their
DNA / have one copy of gene without exon / base sequence for probe to
bind to;
3. Accept normal and gene
3. Accept have a deletion mutation
3
(b)
1.
Introns not translated / not in mRNA / (exons) code for amino acids /
introns do not code for amino acids;
1. Accept not expressed
1. Accept polypeptide / protein for amino acids
2.
Mutations of these (exons) affect amino acid sequences (that produce)
faulty protein / change tertiary structure of protein;
2. Accept deletion leads to frameshift
2. In this context, accept affects protein made
3.
So important to know if parents’ exons affected, rather than any other part
of DNA / introns;
Accept converse arguments involving - eg introns do not code
for amino acids / proteins
Reject references to making amino acids, once
3
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(c)
1.
Restriction mapping / described;
2.
DNA / base sequencing (of fragments) / description / name of method;
2
[8]
M6.
(a)
OR
Correct answer: 1.25;
Ignore working
(if wrong answer)
/
= 1 mark
125 but wrong order of magnitude = 1 mark
2
(ii)
C has myosin / thick (and actin / thin) filaments;
OR
A has only actin / thin (/ no myosin / no thick) filaments;
1 max
(b)
When contracted:
Thick & thin filaments/myosin & actin overlap more;
Interaction between myosin heads & actin / cross-links form;
Movement of myosin head;
Thin filaments / actin moved along thick filaments / myosin;
Movement of thin filaments / actin pulls Z-lines closer together;
Displacement of tropomyosin to allow interaction;
Role of Ca2+;
Role of ATP;
Allow ref. to ‘sliding filament mechanism’ /
described if no other marks awarded
4 max
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(c)
(i)
8 has DMD but 3 and 4 do not / 12 has DMD but 6 and 7
do not / neither parent has the condition but their child has;
Allow parents 3 and 4 give 8, parents 6 and 7 give 12
1
(ii)
4 AND 7;
1
(iii)
Parental genotypes: 6 = XDY AND 7 = XDXd
AND
Gametes correct for candidate’s P genotypes ‒ e.g.
XD and Y + XD
and Xd;
Offspring genotypes correctly derived from gametes e.g.
XDXD + XDXd + XDY + XdY;
Male offspring with MD correctly identified: XdY;
Probability = 0.25 / correct for candidates offsprings genotypes;
Accept ¼ / 1 in 4 / 1:3 / 25%
NOT ‘3:1’ / ‘1:4’
4
(d)
(i)
No gene fragment G;
1
(ii)
Only one copy of gene fragment F;
Male has only one X-chromosome / is XY
(c.f. female has two / is XX);
2
(iii)
10 has only one copy of gene fragment G;
10 has only one normal X-chromosome / has one abnormal /
has only one normal allele / has one Xd / is XDXd / is heterozygous;
11 has two normal X-chromosomes / has 2 normal alleles /
is XDXD / has not got Xd / has 2 copies of (F and) G;
3
(e)
(i)
To prevent rejection / prevent antibody production vs. injected cells /
injected cells have (foreign) antigen (on surface);
1
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(ii)
Shows effect of cells / not just effect of injection / not just effect of
salt solution;
1
(iii)
Only one person tested so far ‒ need more to see if similar results /
need more to see if reliable;
Need to assess if new (dystrophin positive) muscle fibres are
functional / if muscle becomes functional;
Can’t tell how widespread effect is in the muscle / sample taken
near injection site;
Need to test for harmful side effects;
Need to test if successful for other mutations of dystrophin gene;
Need to assess permanence / longevity of result/insufficient time
allowed in investigation;
(In this patient) only small response / %;
Further sensible suggestion;
4 max
[25]
M7.
(a)
Cocaine (binding) changes shape of transporter/prevents dopamine binding;
Reject references to active site
Transporter cannot move (bound) dopamine (through membrane / protein /
into cell);
Dopamine remains / builds up in synapses (leading to feelings of pleasure);
3
(b)
(i)
Polymerase chain reaction / PCR;
1
(ii)
Single-stranded DNA;
Reject reference to a single strand of DNA
Bases / sequence complementary to DNA / gene to be identified;
(Radioactively / fluorescent) labelled so that it can be detected;
2 max
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(c)
Mutation changes base sequence of gene / DNA;
Accept references to active site
(Thus) changing amino acid sequence;
Changes tertiary structure / shape of protein/transporter;
Cocaine binding site changes/cocaine cannot bind;
Dopamine can still bind (and be transported);
3 max
[9]
M8.(a)
1.
No effect at 25°C
The question only refers to plants with GB
1. Reject same mass
2.
Keeps growing at 30°C and 35°C / up to 35°C (more than without GB);
3.
Above 35°C, falls but grows more than plant without GB;
3. Accept at all temperatures above 25°C more growth than
without GB
2 max
(b)
(i)
Significantly different / SEs do not overlap ;
Accept converse without GB
1
(ii)
(As temperature increases,)
1.
Enzyme activity reduced / (some) enzymes denatured;
2.
Less photosynthesis, so fewer sugars formed;
3.
Less respiration / less energy / ATP for growth;
4.
Less energy for named function associated with growth
4. Eg mitosis, uptake of mineral ions
4
(c)
1.
(Rubisco activase attaches to thylakoid and) this changes shape / tertiary
structure (of enzyme) / blocks active site / changes active site;
Note - question states enzyme stops working when it attaches
to thylakoid, not before
1. Accept rubisco in this context
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2.
(This) prevents substrate / RuBP entering active site / binding;
2. Accept prevents ES complex forming
2. Accept no longer complementary to substrate / RuBP
2
(d)
1.
GB prevents / reduces binding of rubiscoactivase to (thylakoid
membrane);
1. Accept enzyme instead of rubiscoactivase. Accept rubisco
2.
(Prevents it) up to 35°C;
3.
(So) rubiscoactivase / enzyme remains active;
4.
(So) photosynthesis / light-independent stage still happens;
4. Accept descriptions of light-independent stage
5.
Above 35°C, some binding still occurs but less than without GB, so less
reduction in growth;
4 max
(e)
1.
Looked for information / journals, on crop plants that grow at high
temperatures;
1. “other research” is minimum accepted
1. Accept previous experiments research with temperature
resistant crops
Ignore simple references to looking at previous studies / other
plants - need to relate to this context
2.
(Crop plants cited in this research) contain / make GB;
3.
So assumed making plants produce GB makes them resistant to high
temperatures;
2 max
[15]
M9.(a)
1.
To allow comparison;
2.
Because different number of cells in samples / different times for
incubation / numbers become easier to manipulate;
2
(b)
203.7(%);;
Allow 1 mark for 21.8 / 10.7
Allow 1 mark for correct answer (203.74) but not correctly to 1
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dp
204 = 1 mark
2
(c)
(i)
1.
2.
(At every concentration) uptake is faster at 37°C / at higher
temperature;
Due to faster respiration / ATP production;
2
(ii)
1.
Uptake at 37°C only small increase / levelling off / almost constant
as carrier proteins full;
Accept ‘no (significant) change’
Ignore use of numbers
2.
Concentration of imatinib is not the limiting factor;
2
[8]
M10.(a)
1.
2.
Rank all STs in ascending order;
Find value with same number (of people) above and below.
Accept find middle value
2
(b)
Not ethical to fail to treat cancer.
1
(c)
Yes since with ipilimumab:
1.
2.
Median ST increased by 2.1 months;
Percentage of patients showing reduction in tumours increased from
10.3% to 15.2%;
No because:
3.
No standard errors shown / no (Student) t- test / no statistical test carried
out;
4.
(So) not able to tell if differences are (statistically) significant / due to
chance (alone);
5.
Improvement might only be evident in some patients / no improvement in
some patients;
6.
Quality of (extra) time alive not reported;
If answers relate only to ‘Yes’ or ߢ No’, award 2 marks max
4 max
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(d)
1.
2.
3.
4.
Faulty protein recognised as an antigen / as a ‘foreign’ protein;
T cells will bind to faulty protein / to (this) ‘foreign’ protein;
(Sensitised) T cells will stimulate clonal selection of B cells;
(Resulting in) release of antibodies against faulty protein.
3 max
[10]
M11.(a)
1.
2.
3.
Methylation prevents transcription of gene;
Protein not produced that prevents cell division / causes cell death /
apoptosis;
No control of mitosis.
3
(b)
1.
2.
3.
Scatter graph;
Fat on x axis and death rate on y axis;
(Because) looking at relationship between two discrete / independent
variables.
3
(c)
1.
2.
(Trend) shows positive correlation / shows the more fat in diet, the higher
death rate from breast cancer;
But number of points off line / anomalies.
2
[8]
M12.(a)
1.
Removes (main / largest) source of oestrogen / (different) mice produce
different amounts of oestrogen;
Accept: so oestrogen from ovaries not a confounding variable
− idea of.
2.
(Allows) oestrogen to be controlled / oestrogen to be made by aromatase
only / only oestrogen made in lungs to be involved.
Reject: references to injection of aromatase.
2
(b)
1.
(Anastrozole) prevents / reduces oestrogen production;
2.
(Fulvestrant) stops remaining oestrogen binding / less oestrogen binds to
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receptors.
Note: brackets around drug names.
2
(c)
(Yes for Group T)
1.
Least tumours per animal (from fig. 1);
Accept: ‘mean values’ for tumour area.
2.
Lowest (mean) tumour area / size (from fig. 2);
3.
Lowest top of range;
(But)
4.
Means (tumour area) are similar;
Where candidates confuse range and standard deviation, do
not give credit.
5.
6.
7.
8.
9.
10.
Ranges overlap / share values so differences may not be real / treatments
may be just effective in reducing tumour;
Ignore significance
Range affected by outliers / SD’s would be better;
Done on mice / not done on women / humans;
Only 10 mice used per group / small sample size so may not be
representative / reliable;
Might be side effects;
Only did for 15 weeks so maximum effect of drugs may not have been
seen.
5 max
(d)
1.
Tumours may be different depths / area does not take depth into account
/ tumours are 3-D / are not 2-D;
Neutral: different sizes
Accept: height / thickness for depth
2.
(Measure) tumour volume / mass / weight.
2
(e)
1.
Allows tumours to grow / develop / form;
Neutral: gives drug more time to work.
2.
(So) can investigate treatment rather than prevention (of tumours) / when
tumour / cancer is more advanced.
Accept: to see whether it can destroy / treat / stop growth of a
tumour (that already exists) / to allow / assess treatment of a
tumour
2
(f)
1.
Unethical (not to treat patients) / may increase probability of patients
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dying / getting more ill;
Reject: references to giving people tumours
2.
Use normal cancer drugs / treatment.
Accept: named type of cancer treatment, e.g. chemotherapy
2
[15]
M13.(a)
1.
Cut (DNA) at same (base) sequence / (recognition) sequence;
Accept: cut DNA at same place
2.
(So) get (fragments with gene) R / required gene.
Accept: ‘allele’ for ‘gene’ / same gene
2
(b)
1.
2.
Each has / they have a specific base sequence;
That is complementary (to allele r or R).
Accept description of ‘complementary’
2
(c)
1.
Fragments L from parent rr, because all longer fragments / 195
base pair fragments;
Ignore: references to fragments that move further / less,
require identification of longer / shorter or 195 / 135
Accept: (homozygous) recessive
2.
Fragments N from parent RR, because all shorter fragments / 135 base
pair fragments;
1 and 2 Accept: A3 for 195 and A4 for 135
2. Accept: (homozygous) dominant
3.
(M from) offspring heterozygous / Rr / have both 195 and 135 base pair
fragments.
Accept: have both bands / strips
Reject: primer longer / shorter
3
(d)
1.
2.
(Cells in mitosis) chromosomes visible;
(So) can see which chromosome DNA probe attached to.
2
(e)
(i)
1.
For comparison with resistant flies / other (two) experiments
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/ groups;
Ignore: compare results / data / no other factors
2.
To see death rate (in non-resistant) / to see effect of insecticide in
non-resistant / normal flies.
Accept: ‘pesticide’ as ‘insecticide’
Accept to see that insecticide worked / to see effect of enzyme
2
(ii)
(PM must be involved because)
1.
Few resistant flies die (without inhibitor);
2.
More inhibited flies die than resistant flies;
3.
(PM) inhibited flies die faster (than resistant flies);
(Other factors must be involved because)
4.
Some resistant flies die;
5.
But (with inhibitor) still have greater resistance / die slower than
non-resistant flies.
Accept: (with inhibitor) die slower than non-resistant flies
4 max
[15]
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