Forensic Science QP New Syllabus (2010-2012)

Edexcel GCE in Biology © Edexcel Limited 2007 Sample Assessment Materials 61

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6. (a) Forensic entomology can be used to estimate the time of death of a mammal. Adult female blowflies soon arrive to lay their eggs on the body and the blowfly life cycle follows a precise sequence. The diagram below shows the sequence and times (in hours) for each stage when the surrounding temperature is 21 °C.

(i) Using information in the diagram, calculate the total percentage of the life cycle that a blowfly spends as a larva when the surrounding temperature is 21°C.

Answer .............................. %(2)

(ii) Temperature has an effect on the length of the blowfly lifecycle. Suggest an explanation for the effect of temperature on the length of the blowfly lifecycle.

................................................................................................................................

................................................................................................................................(2)

Larval stages

130 hours

22 hours

27 hoursEggs23 hours

Adult blowfly12 hours

Pupa131 hours

Sample Assessment Materials © Edexcel Limited 2007 Edexcel GCE in Biology62

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(iii) Suggest two factors, other than temperature, that may affect the timing of the blowfly lifecycle and lead to an incorrect estimate of the time of death.

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................................................................................................................................(3)

(b) Time of death can also be estimated by studying the degree of rigor mortis in muscles. Describe how rigor mortis in muscles occurs.

.......................................................................................................................................

.......................................................................................................................................(3)

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

.......................................................................................................................................

.......................................................................................................................................(3)

(Total 13 marks)

*N36364A01224*

4 The bases in a gene code for the synthesis of a protein. Gene mutations can influence the metabolism of an organism.

(a) (i) The diagram below shows the bases on the template strand of DNA in the part of a gene that codes for a short sequence of amino acids in an enzyme.

A A C TA G T T G G C A A G T G G T C A C

Each of the following statements is about this sequence of bases. For each statement, place a cross in the appropriate box to show whether it is true or false.

Statement True False

This sequence of bases could be used as a template during translation

A strand of mRNA could be synthesised using this sequence

This sequence codes for 7 amino acids during protein synthesis

(ii) Name and describe the structures where the polypeptide chain of this enzyme would be synthesised.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*N36364A01324* Turn over

(b) Chlamydomonas is a single-celled photosynthetic organism that lives in well-illuminated ponds. In populations of Chlamydomonas, a gene mutation occasionally occurs. This mutation enables Chlamydomonas to take in organic compounds produced by other organisms and use them as a source of energy.

(i) Explain what is meant by the term gene mutation.(2)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(ii) A population of Chlamydomonas was found in a pond in the centre of a developing forest of fast-growing trees. Suggest how the allele frequency for this mutation could change as the forest develops. Give reasons for your answer.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(Total for Question 4 = 11 marks)

*N36364A01424*

5 Following a burglary, a DNA profile was created using a small sample of blood left behind on a broken window pane. This DNA profile was then compared with DNA profiles from four suspects, S1, S2, S3 and S4. These DNA profiles are shown in the diagram below.

(a) (i) Place a cross in the box next to the name of the enzyme used in the process used to amplify the DNA in the small sample of blood taken from the crime scene.

A endonuclease

B invertase

C polymerase

D transcriptase

(ii) Place a cross in the box next to the name of the process that could be used to separate DNA fragments to create the profiles shown in the diagram above.

A amniocentesis

B electrophoresis

C endocytosis

D chromatography

Samplefrom

window S1 S2 S3 S4

(iii) Suggest which of the suspects is most likely to have left the blood sample on the broken window pane. With reference to the theory used in DNA profiling, explain how you came to this conclusion.

Suspect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Explanation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*N36364A01624*

(b) Explain why evidence from DNA profiles may not be absolutely conclusive.(2)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(c) Suggest how DNA profiling could be useful to scientists who examine fossils of animals and plants.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*N37095A0224*

Answer ALL questions.

Some questions must be answered with a cross in a box . If you change your mind about an answer, put a line through the box and then mark your new answer with a cross .

1 Forensic scientists use several different types of evidence to estimate the time of death of a body.

(a) Place a cross in the boxes next to the two types of evidence that could be used by a forensic scientist to estimate the time of death of a body.

(2) Degree of muscle contraction

Length of fingernails

Signs of decomposition

Skin pigmentation

(b) The core temperature of a body can also be used to estimate the time of death. This can be recorded by measuring the temperature of the rectum.

The table below shows the mean core temperature, measured at 2-hour intervals after death, using data from a large number of bodies. The standard deviation from each of the means is also shown.

Time after death / hours

Mean core temperature / °C

Standard deviation from the mean / °C

2 36.7 0.9

4 36.0 1.1

6 35.3 1.3

8 31.3 1.5

10 29.6 1.7

12 28.1 2.0

14 26.7 2.3

16 25.5 2.6

18 25.0 2.9

20 23.6 3.1

22 22.8 3.3

24 22.3 3.4

26 21.8 3.4

Explain what the data indicates about the reliability of using core temperature to estimate the time of death.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(c) Suggest three factors that could influence the rate at which a body cools after death.

1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*N37490A02028*

6 The diagram below shows the sequence of events leading to polypeptide synthesis.

(a) Place a cross in the box next to the correct term that completes each of the following statements.

(i) Transcription takes place in the(1)

A Golgi apparatus

B lysosome

C nucleus

D ribosome

(ii) A triplet of bases that could not be found in mRNA is(1)

A Adenine Adenine Guanine

B Adenine Thymine Guanine

C Adenine Cytosine Guanine

D Adenine Uracil Guanine

Transcription forms pre-mRNA

Pre-mRNA modified to give mRNA molecules

Translation of mRNA molecules to synthesise

polypeptides

stage A

stage B

stage C

(iii) The sequence of triplets on a section of DNA used to form a strand of pre-mRNA is a

A cistron

B codon

C neutron

D photon

(b) Describe how free nucleotides are bonded together in the correct sequence in pre-mRNA, at stage A.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(c) A strand of pre-mRNA consists of exons and introns. Exons are sections that can be used during translation for polypeptide synthesis. Introns are lost during the modification of pre-mRNA at stage B and are not used during translation.

During this modification, a variety of mRNA molecules is formed. Each molecule contains all or only some of the original exons in the pre-mRNA. However, the sequence of the exons in a strand of mRNA will always be the same as in the original pre-mRNA.

(i) Explain the function of the codons at each end of a strand of mRNA, during the process of translation.

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*N37490A02228*

(ii) Suggest why a variety of different protein structures could be formed from the polypeptides synthesised using the mRNA molecules from a single gene.

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*P38174A01428*

4 Muscle contraction in mammals involves two fibrous proteins, actin and myosin. These slide over each other to reduce the length of the muscle.

(a) State two differences between fibrous proteins, such as actin and myosin, and globular proteins, such as enzymes.

1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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(b) During the first few hours after the death of a mammal, the muscles undergo a characteristic contraction known as rigor mortis.

(i) Place a cross in the box next to the factor that might influence the rate of progress of rigor mortis in a muscle immediately after death.

A Degree of decomposition of the muscle

B Oxygen concentration of the atmosphere

C Presence of drugs in the body

D Presence of egg laying insects

(ii) Suggest two environmental factors that influence the rate of progress of rigor mortis in a muscle immediately after death.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*P38174A01528* Turn over

(c) In an investigation of rigor mortis in rats, the tension due to contraction was measured in leg muscles and jaw muscles at intervals of 30 minutes after death. The tension was recorded as a percentage of the normal full contraction of each muscle in the live animal.

The graph below shows the results of this investigation.

Using the data in the graph, suggest why a forensic scientist would need to consider rigor mortis in several muscles of a body when estimating the time of death.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Leg muscle Jaw muscle

100 –

80 –

60 –

40 –

20 –

–20 –

–40 –

2.0–

2.5–

Time after death / hours

*P38174A02028*

6 Osteocalcin is a structural protein found in the bones of mammals. The sequence of the amino acids in osteocalcin can be determined using mass

spectrometry.

The sequences of the first 20 amino acids in the primary structure of osteocalcin from the bones of humans and some apes are shown in the table below.

Each amino acid is represented by a capital letter.

Mammal

Amino acid number

1 5 10 15 20

Human Y L Y Q W L G A P V P Y P D P L E P R R

Chimpanzee Y L Y Q W L G A P V P Y P D P L E P R R

Orang utan Y L Y Q W L G A P V P Y P D P L E P K R

Gorilla Y L Y Q W L G A O V P Y P D P L E P K R

(a) Place a cross next to the most appropriate answer that completes each of the following statements about these sequences of amino acids.

(i) The number of nucleotides in the gene for osteocalcin production used for each of these sequences is

(ii) The type of bond that links the amino acids in the primary structure of osteocalcin is

A disulphide

B hydrogen

C ionic

D peptide

(iii) The structure in which the amino acids in the primary structure of osteocalcin would be linked together is a

A centriole

B lysosome

C nucleolus

D ribosome

(b) (i) Using the data in the table, suggest with reasons what conclusions scientists might make about the ancestral relationships of humans and apes.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(ii) Suggest how DNA analysis could give further evidence for their conclusions.(2)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*P38174A02228*

(iii) Describe how gel electrophoresis can be used to analyse DNA.(3)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*P39505RA0224*

Answer ALL questions.

Some questions must be answered with a cross in a box . If you change your mind about an

answer, put a line through the box and then mark your new answer with a cross .

1 During DNA profiling, the polymerase chain reaction (PCR) can be used to amplify a sample of DNA.

The diagram below shows how substances X, Y and Z are involved in the PCR.It also gives the temperature treatments T1, T2 and T3 at various stages.

The DNA sample is mixed with X, Y and DNA polymerase.

This mixture is placed into a PCR machine.

The mixture is treated (T1) to separate Z.

The mixture is treated (T2) to allow X to attachto Z.

The mixture is treated (T3) to allow DNA polymerase to use Y to assemble a

complementary Z.

The cycle of heating and cooling is repeated approximately 30 times.

*P39505RA0324* Turn over

(a) Name substances X, Y and Z.(3)

Substance X . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Substance Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Substance Z . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(b) Place a cross in the box next to the correct statements for treatments T1, T2

and T3.(3)

(i) Treatment T1

A heated to 90–95 °C

B heated to 75 °C

C cooled to 55–60 °C

D cooled to 4 °C

(ii) Treatment T2

B heated to 75 °C

D cooled to 4 °C

(iii) Treatment T3

B heated to 75 °C

D cooled to 4 °C

*P39505RA0424*

(c) Suggest reasons for each of the following.

(i) DNA polymerase from human sources is not suitable for use in a PCR machine.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(ii) Species of plants cannot be identified from woody (xylem) material using PCR and DNA profiling.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*P39511A01428*

5 A pathologist was called to examine the body of a young man found partly-buried in a shallow grave. The initial examination of the body provided evidence that could be used to estimate the time of death of the young man.

One source of evidence used for an estimation of the time of death was the remains of insects found on the body.

The table below describes some of the types of insect remains found and the pathologist’s notes.

Type of insect Life cycle stage Pathologist’s notes

Chrysomya rufifacies (blowflies) Pupa cases Pupa cases empty

Dermestes maculates (beetles) Third stage larval skins Good condition

Necrobia rufipes (beetles) Adult Active

(a) Place a cross in the box next to the term that describes the use of evidence provided by insect remains on a dead body.

A forensic bryology

B forensic entomology

C forensic mycology

D forensic neurology

(b) The flow diagram below shows the main stages in the life cycle of blowflies and beetles.

EGG ��LARVA ��PUPA ��ADULT

(i) Place a cross in the box next to the factor that would have the most effect on the rate of development of each stage of the life cycle of insects on this dead body.

A interspecific competition

B light

C predation by birds

D temperature

(ii) Suggest how the pathologist might use the information in the table and the flow diagram to estimate the time of death of the young man.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*P39511A01628*

(c) Suggest how useful each of the following additional sources of evidence would be for the pathologist in determining the time of death of this young man. Give an explanation for each of your answers.

(i) Body temperature(2)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

(ii) State of decomposition(2)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*P39511A02428*

8 DNA is found in chromosomes and consists of double-stranded polynucleotide molecules. The sequence of bases in DNA forms the basis of what is known as the genetic code.

(a) Explain why a molecule of DNA can be described as a double-stranded

polynucleotide.(3)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

*P39511A02528*

*(b) Describe how the sequence of bases in a DNA molecule would be used to form the primary structure of a protein.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TOTAL FOR PAPER = 90 MARKS

Forensic Science QP New Syllabus (2010-2012)

blowfly lifecycle

surrounding temperature

effect of temperature

edexcel gce

blowfly life cycle

biology edexcel limited

b time of death

degree of rigor mortis

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