forensic science ms new syllabus (2010-2012)

7/27/2019 Forensic Science MS New Syllabus (2010-2012)

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Sample Assessment Materials Edexcel Limited 2007 Edexcel GCE in Biology134

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Question

6.(a)(i) Using information in the diagram, calculate the total percentage of thelife cycle that a blowfly spends as a larva when the surroundingtemperature is 21 C.

Correct Answer MarkCorrect answer (with or without working) = 2 marks

Answer: 51.9% (accept 52% or 51.88%)

Correct working with incorrect answer = 1 mark

Accept any working that would give correct answer

eg 179 / 345 x 100 = 52%

2

QuestionNumber Question

6.(a)(ii) Temperature has an effect on the length of the blowfly lifecycle. Suggestan explanation for the effect of temperature on the length of the blowflylifecycle.

Correct Answer Mark

Award one mark for each of the following points in context toa maximum oftwo marks.

1. idea that length of life cycle is dependant on metabolicrate of blow fly;

2. metabolic rate is determined by enzyme activity/eq;

3. as temperature increases (up to an optimum) enzymeactivity increases;

4. idea that as a result of temperature increase (to a max)length of lifecycle decreases;

2


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Edexcel GCE in Biology Edexcel Limited 2007 Sample Assessment Materials 135

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Question

6.(a)(iii) Suggest two factors, other than temperature, that may affect the timing ofthe blowfly life cycle and lead to an incorrect estimate of the time ofdeath.

Answer Mark

Award one mark for each of the following points in context toa maximum oftwo marks.

1. humidity;

2. drugs;

3. oxygen;

4. ref. to genetic differences;

2

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Question

Q6(b) Describe how rigor mortis in muscles occurs.

Answer Mark

Award three marks for the following in context.

1. Muscle cells deprived of oxygen

2. Respiration becomes anaerobic/reference to lactic acid

3. Fall in pH

4. Inhibits enzymes

5. ATP no longer produced

6. Bonds between muscle proteins become fixed

3


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Sample Assessment Materials Edexcel Limited 2007 Edexcel GCE in Biology136

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Question

6.(c) The process of succession occurs in plant communities as well as in a deadbody. Compare these two forms of succession.

Answer MarkAward one mark for each of the following points in context toa maximum ofthree marks.

1. as each organism feeds it changes the body /environment

2. this allows conditions suitable for colonisation/growthof other species

3. ref to other organisms eg microbes

4. in plant succession many early species are replacedover time

5. in this case most of the early insects remain as otherscolonise

6. suitable reference to climax community in plants

7. {longer timescale / larger area} in plants

3


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10016BI0

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4(a)(i) Statement TRUE FALSE

This sequence of basescould be used as a templateduring translation 6

A strand of mRNA couldbe synthesised using thissequence 6

This sequence codes for 7amino acids during proteinsynthesis

6

1 mark each correct box ;;;[crosses in both boxes for a statement = 0]

(3)

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4(a)(ii) 1. ribosomes / RER / rough endoplasmic reticulum /poly(ribo)some ;

2. descriptive feature e.g.(for ribosome or polysome) {ribosomal RNA /

rRNA} / protein component / {two sub-units /large and small sub-unit}(for RER) ribosome attached to membrane ; (2)

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4(b)(i) 1. {change / eq} in DNA ;2. ref to {change / deletion / addition / duplication

/ substitution / eq} of {bases / nucleotides} ; (2)


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10016BI0

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4(b)(ii) 1. correct reference to change in frequency ofeither allele e.g. mutant increases / normaldecreases ;

2. idea of reproductive success of the {mutant /non-photosynthetic} individuals ;

3. (as trees develop) pond will be (more) shaded /eq ;

4. (less light means) less photosynthesis possible /eq ;

5. ref to photosynthetic individuals die / {non-photosynthetic / mutant} individuals survive ;6. ref to pass on the {mutation / allele} (for using

organic compounds) / eq ;

7. ref to more organic nutrients in pond ; maximum(4)


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10016BI0

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5(a)(i) C ; (1)

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5(a)(ii) B ; (1)

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5(a)(iii) 1. (S/ suspect) 3 ;2. (S3) matches {all / 9 / eq} of the bands in the

sample ;

3. DNA profiling assumes every individuals DNA is{unique / different} / eq ;

4. apart from identical twins / eq ;5. ref to DNA profiling analyses the {introns / non-

coding blocks / STR / short tandem repeats / eq};

6. non-coding DNA {very variable / hypervariable /eq} ;

7. large number of {introns / non-coding blocks / eq};

8. idea of many {combinations / eq} (at each locus) ; maximum(5)


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5(b) 1. ref to DNA profiling has several stages ;2. ref to {artefacts / contamination / eq} can arise

at any stage ;

3. only {a few sequences / small portion } of DNAanalysed / eq ;

4. ref to possibility of two identical profiles fromunrelated individuals ;

5. {identical twins / closely-related individuals / eq}may show same profile / eq ;

maximum(2)

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5(c) 1. comparisons made between DNA from fossils andother organisms ;

2. to find genetic relationships / how closely related/ eq ;

3. ref to used in {taxonomy / classification / eq} ;4. to understand evolutionary lines / to determine

common ancestor / eq ;maximum(2)


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6BI04_011006

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1(a) cross next to degree of muscle concentration ;

cross next to signs of decomposition ;(2)

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1(b)1. idea of SD {measures / shows} {spread /

range / eq} of data ;

2. Idea of most readings are within {+ 1 x SD /+ 2 x SD} e.g. approx 60% readings within

(+ )1 x SD / approx 90% readings within (+) 2 xSD ;

3. idea that as length of time increases, SDincrease / eq ;

4. idea of more variability (in temperature) astime increases / eq ;

5. comment on change in reliability of time ofdeath with time / eq ;

6. estimate (of time of death) can only bewithin a {4 / 5 / 6 / 7} hour period ;

7. use of manipulated data ;max(4)

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1(c) three from the following:

{(body) mass/ BMI / weight / eq}{(subcutaneous) fat /eq}surface area,{ambient / eq } temperatureimmersion in waterage (of person at death)

skin colourthickness of hairgenderclothingblood losshumidityair movement{core / body} temperature at time of death ;;; (3)


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6BI04_011006

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Answer Mark

5(a)Description DNA

onlyRNAonly

Both DNAand RNA

Polymer formed

from a single strandof nucleotides

9Pentose present inthe nucleotides 9

Adenine, cytosine,guanine andthymine present

9

Nucleotides linkedby phosphodiesterbonds

9

all rows correct 2 markstwo or three rows correct 1 mark

(2)

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Answer Mark

5(b)(i)1. DNA strands {separate / unzip / eq} ;2. idea that one DNA {strand / eq} used as

template (to form mRNA) / eq ;

3. from free nucleotides / eq ;4. reference to complementary base pairing ;5. reference to hydrogen bonding ;6. correct reference to {RNA-polymerase / DNA

helicase} ;

7. credit correct sequence of bases on {mRNA /DNA} ;

max(3)


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6BI04_011006

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5(b)(ii)

1. reference to specific amino acid attachmentto tRNA ;

2. idea that anticodon (on tRNA) {attaches /binds / lines up / eq} to the {codon / triplet}on mRNA ;

3. example quoted using the information in thediagram e.g. tRNA with alanine has CGAanticodon which binds to GCU on mRNA ;

4. idea that two tRNA held in ribosome (at anyone time) ;

5. reference to formation of peptide {bonds /links} (between adjacent amino acids) ;

6. reference to peptidyl transferase ; max(3)

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5(c)

1. stop codon ;2. used to end the {sequencing / further

attachment of tRNA / eq} ;

3. release of the {polypeptide / ribosome} /eq ; max(2)


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6BI04_011101

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6(a)(i) C ;

(1)

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6(a)(ii)B ;

(1)

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6(a) (iii)A ; (1)

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6(b) 1. idea of sequence of {bases / nucleotides}on DNA determines sequence on (pre-)mRNA ;

2. reference to complementary base pairing/ stated example e.g. AU / CG / GC / TA(DNA: mRNA) ;

3. reference to formation of bonds bycondensation reaction ;

4. phosphodiester {bonds / links} ;5. reference to RNA-polymerase ; max(3)

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6(c)(i) 1. reference to {start / stop / nonsense}(codon) ;

2. start (codon) needed to begin{polypeptide synthesis / eq} / {stop /nonsense} (codon) needed to end{polypeptide synthesis /eq } / eq ; (2)


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6BI04_011101

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6(c)(ii) 1. reference to {difference / variations / eq }of {exons / mRNA} ;

2.

reference to different {primary structure/ sequence of amino acids} ;

3. reference to {secondary / tertiary }structure of proteins depends on primary{structure / sequence} / eq ;

4. due to {change in / different} bonds ;5. {hydrogen / ionic / disulphide} bonds ;6. reference to different 3D shape / eq ; max

(3)


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4(a)1. fibrous long / linear / straight (chains),

globular compact / spherical / eq ;

2. globular are folded and fibrous are not / eq ;3. globular are soluble and fibrous are not / eq ;4. fibrous involved in {structural / eq} and globular

are not ;

5. globular involved in {catalysis / metabolism / eq}and fibrous are not ; (2)

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4(b)(i)C ; (1)

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4(b)(ii)Any

twofrom:

1. physical damage / eq ;2. immersion in water / eq ;3. (external) temperature / eq ;4. burning / eq ;5. electrocution / eq ;6. reference to {clothing / eq} ;

7. wind / air movements / eq ; (2)


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Answer Mark

4(c)1. reference to not {all / both / eq} muscles

{contract / relax / reach (full) rigor / eq} at

same {time / rate / eq} ;

2. idea of jaw muscle contracting before legmuscle / eq ;

3. idea of jaw muscle reaches {full contraction /rigor} before leg muscle / eq ;

4. jaw starts contraction {0.5 / 0.8 / 0.9} hoursbefore leg OR jaw reaches (full) rigor 2.5

hours before leg ;

5. reference to {full contraction / rigor} inmuscle does not last very long ;

6. idea of leg is still contracting while jaw isrelaxing / eq ; (4)


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6(a)(i)C ;

(1)

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6(a)(ii)D;

(1)

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6(a)(iii)D ; (1)

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6(b)(i)1. humans more closely related to chimp (than

to orang utan and gorilla) / eq ;

2. reference to humans and chimps more closelyrelated to orang utan than gorilla ;

3. reference to similarity of sequence indicatescloseness of ancestral relationship / eq ;

4. human and chimp sequence identical / eq ;5. orang utan has one difference, gorilla has two

differences / eq ;

6. reference to {number 19 for orang utan / number9 and 19 for gorilla} different ; (4)


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6(b)(ii)1. reference to similarity (of DNA) indicates

closeness of relationship ;

2. because genes are sections of DNA / eq ;3. genes are the codes for protein / eq ; (2)

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6(b)(iii)1. reference to source of DNA sample, e.g.

blood, saliva, semen ;

2. reference to small samples of DNA can beamplified by PCR ;

3. reference to use of (restriction / eq) enzymes to{break / eq} DNA ;

4. reference to use of {electro potential /potential difference / eq} ;

5. reference to {treatment / staining / eq} ;6. show up as {bands / bars / eq} ;7. reference to the {number of bands / eq} that

match indicates similarity of the DNA ; (3)


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1(a)Substance X = (DNA)primer(s) ;

Substance Y = (mono)nucleotide(s) ;

Substance Z = DNA strand(s) ;

(3)

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1(b)(i) A ;(1)

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1(b)(ii) C ;(1)

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1(b)(iii) B ; (1)

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1(c)(i) 1. Idea that human enzymes will not work at {high /these/ above 37oC eq} ;

2. reference to {denaturation /change in shape ofactive site}(at temperatures in PCR) ;

(2)


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Answer Mark

1(c)(ii)1. (xylem / wood) made of dead material / has no

{living material / cytoplasm / cell contents/ nuclei

/ mitochondria} / eq ;

2. no {DNA / nucleic acid} present / eq ;(2)

6BI04_011201


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5(a) B forensic entomology ; (1)

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5(b)(i) D temperature;(1)

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5(b)(ii) 1. idea that the body has been dead for awhile ;

2. (because) more than one species of insectpresent / eq ;

3. reference to succession (of insect species) ;4. idea that life cycle {times / stages} of the

insects are {known / used / eq} ;

5. idea that life cycle times depend on(environmental) temperature ;

6. credit specific ref to information in table e.g.blowfly cycle complete ;

(3)

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Answer Mark

5(c)(i) 1. idea that a drop in body temperature islinked to time after death e.g. algor mortis ;

2. idea that factors affect temperature drope.g. environmental temperature, body size,clothing ;

3. (useful because ) time of death can becalculated if (ambient) temperature known /eq ;

4. only useful for short period of time followingdeath e.g. 24 hours, a day ;

(2)


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5(c)(ii) 1. idea that body decomposes in a specificsequence (with time) ;

2. idea that factors affect decomposition e.g.environmental temperature, wounds ;

3. (not useful) if all the body has decomposed/ eq ;

(2)


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8(a) 1.(Double-stranded because made of) twostrands ;

2.(strands joined) by hydrogen bonds(between bases ) ;

3. (polynucleotide) of {many / eq}nucleotides ;

4.(nucleotides) linked by phospho(di)esterbonds / eq ; (3)

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Answer Mark

*8(b)

QWC

Take into account quality of written

communication when awarding thefollowing points.

1. idea of sequence of bases {forming thegenetic code / determines the amino acid

sequence} ;

2. idea that one triplet codes for an aminoacid;

3. ref to (DNA) acting as a template ;4. reference to transcription OR detail of

transcription e.g. DNA unzips, mRNAsynthesis ;

5. idea that mRNA moves from nucleus tocytoplasm / eq ;

6. reference to translation OR detail oftranslation e.g. role of ribosome, codon-

anticodon interaction ;

7. idea that tRNA carries an amino acid ;8. ref to formation of peptide bonds between

amino acids ;

9. idea that primary structure is the{sequence /order / eq} of amino acids ;

10.comment on post-transcriptional

modification of mRNA (betweentranscription and translation)e.g. removalof introns, splicing ;

(5)

forensic science ms new syllabus (2010-2012)

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