CIE A Level Biology

Topic Questions

A LevelBiologyCIETopic Questions19. Genetic Technology19.2 Genetic Technology Applied to Medicine

Syllabus Edition

First teaching 2020

Last exams 2024

|

19.2 Genetic Technology Applied to Medicine

DownloadView
Easy
Medium
Hard
Easy
Medium
Hard
1a
Sme Calculator2 marks

The production of proteins to benefit humans using recombinant DNA technology utilises cells from both prokaryotic and from eukaryotic organisms.

Explain why the production of such proteins is usually carried out by eukaryotic cells, such as yeasts or animal cells in culture, rather than by prokaryotic cells. 

How did you do?

1b
Sme Calculator3 marks

State three advantages of using genetic engineering to produce recombinant human proteins.

How did you do?

1c
Sme Calculator3 marks

Column 1 of Fig. 1 shows three separate human proteins that have been produced successfully using genetic modification of a separate organism. f3~9LX_f_cie-ial-19-2-q1c-e---sq

Fig. 1

Join one of the boxes from Column 1 to the most appropriate box in Column 2 with a straight line.

Do the same linking the boxes in Columns 2 and 3. 

How did you do?

1d
Sme Calculator2 marks

Prior to the use of transgenic organisms to produce insulin, diabetic patients were often given injections of insulin extracted from the pancreases of pigs or cows.

State two advantages of treating diabetics with recombinant insulin over the use of animal-extracted insulin.

How did you do?

Did this page help you?

2a
Sme Calculator2 marks

Fig. 1 below shows a representation of a gene probe.

4-1

Fig. 1

Identify the part of the probe in Fig. 1 labelled X and describe its role.

How did you do?

2b
Sme Calculator1 mark

DNA probes are used to test for the presence of a particular allele. The DNA being tested is split into separate strands and the probe in Fig. 1 will bind to the complementary base sequence on the DNA strand.

State the name of this binding process.

How did you do?

2c
Sme Calculator3 marks

A patient decided to undergo genetic screening for a particular inherited condition.

Describe the process of genetic screening.

How did you do?

2d
Sme Calculator2 marks
The offer of a genetic screening test is often accompanied by genetic counselling.

Give two reasons why a patient might choose to receive genetic counselling.

How did you do?

Did this page help you?

3a
Sme Calculator2 marks

Name two techniques that can be used to obtain cells from a growing foetus in order for that foetus to undergo genetic screening.

How did you do?

3b
Sme Calculator1 mark

One of the main problems of finding effective gene therapies is that of gene delivery.

Give one explanation of why gene delivery has been largely difficult to implement.

How did you do?

3c
Sme Calculator2 marks

Some gene therapies are being developed for delivery to patients in vivo, whereas other are delivered ex vivo.

Compare and contrast the terms in vivo and ex vivo in this context.

How did you do?

3d
Sme Calculator2 marks

A couple contemplating whether to have children are concerned about the risk of their child(ren) being born with cystic fibrosis, due to the presence of cases of cystic fibrosis in their extended families in previous generations.

Both would-be parents are non sufferers of cystic fibrosis, which is a recessive condition.

Outline the choices that genetic screening may offer this couple in their family planning considerations. 

How did you do?

Did this page help you?

1a4 marks

Human Factor VIII is a protein required for the process of blood clotting. Recombinant human clotting factor VIII (rhFVIII) can be produced in the kidney or ovary cells of hamsters.

Suggest how rhFVIII can be produced using hamster cells.

How did you do?

1b2 marks

Before the production of rhFVIII, factor VIII protein was extracted from the blood of human donors.

State two advantages of producing rhFVIII rather than extracting factor VIII from human blood.

How did you do?

1c3 marks

Recent research has shown that it is possible to produce rhFVIII using human embryonic kidney (HEK) cells. Scientists believe that this could be advantageous because the post-translational modifications that take place in hamster cells are different to those that occur in human cells. rhVIII produced in human cells would therefore be identical to factor VIII produced by fully developed humans.

(i)

Suggest what might happen to proteins during post-translational modification.

[2]

(ii)

Suggest why it is preferable to produce factor VIII that is identical to that produced by fully developed humans.

[1]

How did you do?

1d3 marks

rhFVIII is essential for the treatment of haemophilia, a genetic condition in which non-functioning factor VIII means that blood does not clot.

Haemophilia is caused by a mutation in a gene located on the X chromosome. The dominant F allele codes for normal factor VIII while the mutated f allele codes for non-functioning factor VIII.

A male with haemophilia has a child with a heterozygous woman. Give the phenotype probabilities for their children.

How did you do?

Did this page help you?

2a
Sme Calculator6 marks

The polymerase chain reaction (PCR) is used to produce large quantities of DNA from a very small original sample. The main steps of one PCR method are shown in Fig. 1.

fig4-1-qp-specimen-2022-9700-04

Fig. 1

(i)

Explain why it is necessary to heat the mixture to 95 °C (step 1).

[2]

(ii)

Explain why primers are included in the mixture.

[2]

(iii)

Explain why the enzyme Taq polymerase, rather than any other type of DNA polymerase, is used in PCR.

[2]

How did you do?

2b
Sme Calculator10 marks

The presence of a faulty allele of the gene BRCA2 can lead to an increased chance of developing breast cancer. There are many different faulty alleles of the gene BRCA2.

People who are considered to be at risk of breast cancer may choose to be tested for the presence of these alleles in their genomes.

A microarray can be used to test blood samples for the presence of these alleles. The microarray contains DNA probes for different faulty alleles of the BRCA2 gene.

(i)

State the meaning of the term genome.

 [1]

(ii)

Suggest which type of cell from a blood sample is suitable for testing for the presence of these faulty alleles.

   Give a reason for your choice.

[1]

(iii)

Outline how faulty alleles of the BRCA2 gene can be detected using the microarray.

[4]

(iv)

Outline the advantages of screening for faulty alleles of the BRCA2 gene.

[4]

How did you do?

Did this page help you?

1a4 marks

BRCA1 and BRCA2 are genes that code for proteins involved with the repair of DNA mutations

(i)

State how mutations occur in DNA.

[1]

(ii)

Suggest how mutations in BRCA1 and BRCA2 genes could increase the likelihood of tumour development.

[3]

How did you do?

1b2 marks

Individuals with a family history of breast cancer will often have genetic screening to identify mutations in the BRCA1 and BRCA2 genes.

Outline how genetic screening can reduce the risk of breast cancer in high risk individuals.

How did you do?

1c2 marks

Fig. 1 shows a genetic screening technique.

19-2-fig-2-1
Fig. 1

Use Fig. 1 to suggest how a DNA probe can be used to show the presence of a particular allele.

How did you do?

1d3 marks

Screening for BRCA1 and BRCA2 is carried out in adults, but some other genetic traits are tested for in foetuses prior to birth. In either case the results can bring up difficult decisions and individuals considering or undergoing such screening will often receive help from a genetic counsellor to help them think through ethical and social issues.

Outline the social and ethical issues around genetic screening.

How did you do?

Did this page help you?

2a3 marks

Adult haemoglobin is a protein made up of four polypeptide chains; two alpha chains and two beta chains. 

Beta thalassemia is a genetic condition in which a mutation in the gene for the beta chain of adult haemoglobin either reduces or prevents its production.

Suggest three symptoms of beta thalassemia.

How did you do?

2b5 marks

A form of gene therapy is being trialled for use in the treatment of beta thalassemia. The treatment involves harvesting stem cells from the bone marrow of patients before altering them in the lab and infusing the cells back into the patient's body. 

(i)

Describe the stem cells found in bone marrow.

[2]

(ii)

Outline the process by which the stem cells can be altered.

[3]

How did you do?

2c2 marks

One difficulty with carrying out safe and effective gene therapy is of ensuring that any new DNA is inserted into the right part of a patient's DNA.

Suggest why the insertion of DNA in the wrong location could be a problem.

How did you do?

2d3 marks

Give three other concerns related to gene therapy.

How did you do?

Did this page help you?

3a4 marks

Adenosine deaminase (ADA) is an enzyme involved with multiple chemical reactions inside cells. One effect of ADA deficiency is a lack of lymphocyte maturation.

Outline how ADA deficiency can lead to severe combined immune deficiency (SCID).

How did you do?

3b4 marks

Treatment options for SCID caused by an ADA deficiency include:

  • Enzyme replacement therapy (ERT), in which patients receive injections of recombinant ADA enzymes.
  • Haemoatopoietic stem cell transplant (HSCT), in which patients receive a bone marrow transplant from a donor.

Complete the table below by suggesting an advantage and a disadvantage of each of these treatment types.

  Advantage Disadvantage
ERT    
HSCT    

How did you do?

3c3 marks

More recent treatment for ADA SCID involves the use of gene therapy.

Describe the process of gene therapy for ADA SCID.

How did you do?

Did this page help you?