The diagram shows a DNA profile taken ra6 c(7vr8la. zic iy8from 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 s9bss4zblm vsik,pv /5m 1((q the Polymerase Chain Reaction?

  Unlike the majority of other DNA polymerases, Taq polymerase, wi3+a ,rlp ae(vhich is used in PCR reactions can withstand hiarv,+ e(pl3 iagh temperatures without denaturing. Which of the following is a likely source for Taq polymerase?

  What bond is formed between two glucose mo h6bdyndl xn9:9+- zhxlecules to form maltose?

Gel electrophoresis is a technique often used to analvc /y6wq ysj8*yse DNA molecules. It includes a gel and an electric field. The yvq/s8w6jc*y 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 lagging strand?x wt k,lw -44ys v-n3f)m18at/vkmn toeo, tn)

  Which of these answers is true in relation to the polymt-zzw *9it7 ay9z3miex6 fzk3erase chain reaction?

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 resut /w kx3dbv05s 94h:g2p izqym;mxr e9lts 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 rw3 4+ ww5waz+.a)ia -vtna qethe replication of DNA.


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

  What distinguishes DNA polymerase from RNA polymerase?ah)1 o vxgjn5x:hl j.te2 1p/x

  Which of the following are examples of discoveries jg 5m3fnpg0t, made using radioactive isotope 3,tgpmgf0j 5ns?

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 a replication fork which forms during DNA rep i0snr o6xv bwu6(,*5yod .eyjlication.



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 percentage of nitrogenous basesn(srkx(x9 aq : found in the DNA of Escherichia colx((sakrn q9:x i 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 co,1lrd:)xpt o gmposition of venom samples taken from the Malayan Krait (B. candidus) found in three localities; Malaysia, Indonesia and Thailand. All samples were carefully transported an)1:l grpodx t,d 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 the replication of DNA 1p1w pi8q0klb.

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 steps of the polymerase chain react.d7n( :aoirz) zyu9w sn 2uk.vqu4s9vion (PCR) in the correct oru o7nv(wua)q k9:2ynu 4dssrzv9 .iz.der?

1.Enzymes are needed for genetic modification. Outline the role of zr5q)iu0ifjt/)90ja137lfu su hsj )z 1qgfl named enzymes in genett a0f 7l 1szg5 )))r0ju 1fzij/ sqf3quhlu9jiic modification.

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 polymfhl x +34(u e;1+mdh nmv7jaxverase chain reaction (PCR). The use of PCR revolutionized the biotechnology industry and opened up possibilities for many appl41f+h7v+edu 3vaxxm(hl j ;mn ications.

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 fxq.i15e rps2dzne* yij:n, n,or many research projects. There are various techniques for this type of cloning, but the first steps involving the use of restriction endonucleases and DNA ligation are long and often inefficient. The development of more reliae,x2*5rsiq, 1nd zypjin :. neble 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 using DNA from*w5bru/sa 8nj a crime scene. Locus TH01 was used to identify whether a suspect’s DNA matched the b8jw/u a nr*s5crime scene DNA. The suspect’s two alleles of the gene at Locus 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?l1 +vsfe o-l.:rgb4 va
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 shokwe.e)zee;n-w;j - qr f0 c0epws the DNA band pattern from the first two generations of a bacterial culture. Generation numbers are indicated at the bottom of the diagram. Bacteria were grown before the experiment in a medium containi ;c)-eze.e-;0 kqpjr0fww e enng 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 of a child and the profiles of three 5urizq 7a7qx0potential pairs of parents. Which pair(s) could be the actual parents of the chilqi0x57zr auq 7d?