The diagram shows a DNA ykgo m01 8t2hw m;ru9mprofile taken from a crime scene.


Following are the DNA profiles of the suspects in this crime. Which one is the guilty individual?

  What is the function of th0 vhl/j(j56x .:agva6wtu gfce Polymerase Chain Reaction?

  Unlike the majority of other DNA polymerases, unw8d99d43 iw7qhhy xy*8dyxsr yfvcf01j8 8Taq polymerase, which is used in PCR reactions can withstand high temperatures without denaturing. Which of the following is a likely source fo9hdwc fx8d97yq8syywf xvdh8uy0 n 3ir8 *j14r Taq polymerase?

  What bond is formed between two glucose molehm* *5di4h5cwh.8 sx1vb3lo vxra mb.cules to form maltose?

Gel electrophoresis is a technique often used to analyse DNA molecul(uc1(gdor,uga q 23lt(- zay nes. It includes a gel and an electu lro-gc 3qy(anu 1gdazt(2,( ric field. The diagram below shows the outcome of gel electrophoresis.


1.DNA is a type of nucleic acid. State one location where DNA is found in cells.

2.Deduce, with a reason, which direction the DNA fragment moves through the gel.

3.Distinguish between the functions of DNA and RNA in unicellular organisms.

  Which event happens in the leading strand but not in the lagt+ kfs,id-; rpfc4cs8 5ydan;ging strand?

  Which of these answers is true in relation to the polymerase chain reac qtk*((ubcr ,ution?

I. High temperatures are used
II. It produces exact copies of a segment of DNA
III. It requires DNA ligase and restriction endonucleases

Below is an image showing the re *)6taeg71 fx*seldxoyk. .qsh :imh*sults from a paternity test.

1.State the two properties of DNA fragments that allow them to be separated on a gel.

2.Outline the method used in DNA profiling in paternity testing to reach the stage shown in the diagram.

3.Deduce, with a reason, who is most likely to be the father of:

3.1.Child A

3.2.Child B

4.State one use other than paternity testing for DNA profiling.

5.Draw a circle around the heaviest DNA band in father 4’s sample.

6.Suggest why it is important to analyse the DNA of the mother, as well as the father in paternity testing.

7.State one potential source of error in DNA profiling.

  The diagram below shows the rehn/m7ga rb,.kjw*1 p jplication of DNA.


Which of the following are correct functions of structures P, Q and S?

  What distinguishes DNA polymerase dh)fon *f 9hg mkv7e).p ksx77from RNA polymerase?

  Which of the following are examples of lq;/ft0qz 5 iediscoveries made using radioactive isotopes/z 5;0l qftiqe?

I. Discovery of the light-dependent photosynthesis pathways using the $^14$C and $^12$C isotopes.
II. Discovery of DNA as the main genetic material using the $^32$P and $^35$S isotopes.
III. Discovery of the semi-conservative replication of DNA using the $^15$N and $^14$N isotopes.

The diagram below shows x/u- +xetz*yqu fnc,3*) fxnoa replication fork which forms during DNA replication.



1.On the diagram above, label the following structures.

1.1.The 5' and 3' ends of both template strands.

1.2.With the letter E, label the strand in which replication is continuous.

1.3.With the letter P, label the protein that keeps both strands separated.

2.Compare and contrast the role of DNA polymerase I and DNA primase.

  The table below shows the percentuyd-3wr 0+bzqage of nitrogenous bases found in the DNA of Escherichzr+yqdu- 0w 3bia coli bacteria.
Adenine Cytosine Guanine Thymine
32% 18% 18% 32%
What conclusion can be made based on the data shown in the table above?

Data was collected on the protein composition of venom samples taken5;k j7g3-pjg c aerwb* from the Malayan Krait (B. candidus) found in three localities; Malaysia, Indonesia and Thailand. All samples were cark j-egpc *g3aw;j7r 5befully transported and preserved at temperatures below 20$^{circ}$C. The graph shows the number of different types of protein found in each venom sample.


1.1.Identify the independent and dependent variables in this investigation.

1.2.Venom samples were collected from different snakes, in different localities. Suggest two controlled variables, other than temperature, that would support the collection of comparable samples.

Below are the results from gel electrophoresis of one group of venom proteins.


2.1.Identify the group of venom proteins shown.

2.2.Explain how proteins are separated using gel electrophoresis.

Different mice were envenomed with samples from each of the three localities. It was observed that the venom with the lowest neurotoxicity was from the Malayan krait sampled in Malaysia.

3.Suggest why it was important to transport venom samples at temperatures below 20$^o$C.2
4.List two advantages of using mice as model organisms for humans

The venom samples were further analysed, and it was suggested that the Three Finger Toxins group (3FTx) of proteins contributed significantly to the neurotoxicity of the venom. This prompted a closer analysis of the different types of 3FTx proteins found in each venom sample. The data was presented in a graph.


5.Based on the data, suggest which type of 3FTx protein is most likely responsible for differences in the levels of toxicity observed between the different venom samples. Justify your answer.

The diagram below shows thhp-i8q6d.ffmg ga6) y,x :r bre replication of DNA.

1.Describe the characteristics of the enzyme Taq polymerase.

2.Suggest what the consequences for a cell would be if transcription were to stop.

3.Outline the roles of all enzymes involved in the replication of DNA and in the synthesis of mRNA through transcription.

  Which row represents the st )dg khpaij2gmz*.c. (eps of the polymerase chain reaction (PCR) in the correct order? )g(icap*zj d 2hg..km

1.Enzymes are needed for genetic modification. Outline t o41k:y/q1(ve/outw g lfai6jhe role of named enzymes in genetic modifica yokiaw(vgu1t /l/4o:e61 qfjtion.

2.Outline the stages of the polymerase chain reaction (PCR).

3.Discuss the potential risks and benefits associated with Bt corn.

The image shows a basic principle behind the polymerase chain reactio w r10pgjya8xrikgnr*355ht 6n (PCR). The use of PCR revolutionized the biotechi0*r3prxgag1k r6 y5tjh58n wnology industry and opened up possibilities for many applications.

1.List three uses for the DNA copies that are produced.

2.Outline the function of DNA primers in the polymerase chain reaction.

3.Explain the reason for using Taq polymerase in the polymerase chain reaction.

4.Describe one application of the DNA profiles that are produced by PCR and visualized by gel electrophoresis.

The cloning of plasmids is an essential skill for many research projects. There3 s x)*g 0rgenme 4riz i-qhlw8v8+f.f are various techniques for this type of cloning, but the first steps involving the use of restriction mvn8x 0 gr-fsz.+)ehq g4il8if 3re*w endonucleases and DNA ligation are long and often inefficient. The development of more reliable and economical techniques has been important in increasing our ability to manipulate DNA.
In vivo techniques have been successful in yeast and E.coli using DNA fragments with overlapping nucleotide sequences. However, if the overlapping sequences are too long it becomes problematic and sometimes more expensive because of the size of the primers required. To try to increase the efficiency of this method, further research was carried out, using E. coli and DNA fragments with homologous ends prepared using the PCR technique from template plasmids using Q5 DNA polymerase. In the first experiment, 2.6 kB plasmids were formed inside E. coli from 2 DNA fragments with varying lengths of overlapping nucleotide sequences (nt OL). Successful recombinations could be identified, as only these plasmids led to the fluorescence of the cells.


1.Describe the pattern of successful recombinants for the E.coli colonies shown in the photographs.

2.What is the function of DNA polymerase in the PCR technique?

The cloning accuracy was calculated as the percentage of the total colony number that was fluorescent. The total number of colonies and the cloning accuracy for the different overlapping nucleotide lengths are shown in the table and graph below.


3.Calculate the number of colonies with successful DNA recombinations on the agar plate with 25 overlapping nucleotides.

4.1.Explain how DNA recombination occurs with overlapping nucleotides.

4.2.Suggest a reason for the results seen in the agar plates containing E.coli with DNA fragments with 0 or 6 overlapping nucleotides.

5.Suggest a possible reason for the high cloning accuracy with 9 overlapping nucleotides.

Cloning efficiency was then investigated with different numbers of DNA fragments which had 18 or 25 overlapping nucleotides. The results from the experiment are shown below.


6.From the photographs of the petri dishes, deduce what effect the number of DNA fragments has on the number of colonies with successful DNA recombinations.

7.Calculate the percentage increase in the number of colonies for the 25 nucleotide overlap compared to the 18 nucleotide overlap for the recombination of 2 DNA fragments.

The investigation was extended to see how plasmid size and the number of DNA fragments affected DNA recombination in E.coli. The graphs below show the colony numbers resulting from either 2 DNA fragments or 3 DNA fragments being joined together to form different-sized plasmids (measured in kilobases).



8.Compare and contrast the results for the number of colonies produced from 2 DNA fragments and 3 DNA fragments.

Lastly, the accuracy of the cloning of the plasmids in colonies was tested. Colonies containing the 3 different sized plasmids were selected at random, plasmids were extracted and these were tested using gel electrophoresis. The results of 6 plasmids from each of the 3 different sizes are shown below.


9.Identify the plasmid number and size that has not been cloned accurately.

10.Using all the results provided, discuss whether they support the hypothesis that the most efficient process for bioscience research using plasmid recombination and cloning in bacteria is to use 2 DNA fragments, with 25 nucleotide overlap to form 2.6 kB plasmids.

  A DNA profile was made usingrzkt8 :ps,zr)ecv; 4i DNA from a crime scene. Locus TH01 was used to identify whether a suspect’s DNA matched the crime scene DNA. The suspect’s two alleles of the gene at Locusk t4esi v),;r crz:pz8 TH01 are shown below.


The alleles TH01-6 and TH01-4 were separated and visualised with gel electrophoresis. The resulting gel, with two bands of DNA, is shown below.

What is the DNA in Band B and why is this DNA at this position?

  Which of the following is/are characteristic(s) of Taq polymerase?lcxbb7my98 b 3n h:d9g
I. Requires a DNA primer
II. Works well at temperatures above 98°C
III. Used in gel electrophoresis to fluorescent tag DNA molecules

  The diagram below shows the DNA band pattern from the first two generatio3plteal.y -q s m6,i9sns of a bacterial culture. Generation numbers are indicat6 9s3 s etalpi,ql.m-yed at the bottom of the diagram. Bacteria were grown before the experiment in a medium containing a heavy isotope of nitrogen, $^{15}$N, and then transferred to the medium with the light isotope, $^{14}$N which marked the beginning of the experiment (generation 0).

  The diagram shows a DNA profile iae zh4e gvs6e ph.;-;of a child and the profiles of three potential pairs of parents. Which pair(s) could be the actual pa-6;s;vzep4 .eg hehairents of the child?