Genetic Modification (Genetic Engineering) (Edexcel IGCSE Biology)

Exam Questions

2 hours10 questions
1a
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1 mark

Bacteria are genetically modified to make human proteins.

Which part of a bacterium is used in genetic modification?

  A cell wall
  B nucleoid
  C plasmid
  D RNA

1b
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6 marks

The passage describes the use of an industrial fermenter to grow genetically modified bacteria. Complete the passage by writing a suitable word in each blank space.

The hormone called ............................................ is needed to control the blood glucose levels in humans.

Bacteria have been genetically modified to produce this hormone.

The fermenter is cleaned with ............................................ before adding a nutrient broth that contains the genetically modified bacteria.

This cleaning provides aseptic conditions that prevent ............................................ from other bacteria.

Paddles are used to ............................................ the contents.

A gas called ............................................ is bubbled into the fermenter.

The ............................................ is controlled by using a cooling jacket.

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2a
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2 marks

The process of genetic engineering involves the use of vectors.

(i)
Define the term vector when used in the context of genetic engineering. 

(1)

(ii)

Name one example of a vector used in genetic engineering.

(1)

2b
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3 marks

The table below sets out a number of steps in the production of human insulin in a process that involves genetically-engineered bacteria. 

The statements are in the wrong order. 

A A plasmid is cut using restriction enzymes.
B The transgenic bacterial cells are grown in a fermenter.
C The recombinant plasmid is taken up by bacterial cells.
D The cut plasmids are mixed with copies of the human insulin gene.
E The plasmid and the human insulin gene are joined by DNA ligase.

Complete the blank table below to list the steps in the correct sequence.

The first step has been completed for you. 

Step Corresponding letter from the table above
1 A
2  
3  
4  
5  

2c
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2 marks

Describe the benefits of producing insulin by the method described in part (b).

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3a
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2 marks

Define the term transgenic.

3b
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4 marks

The graph below shows insecticide use and the percentage of land used to grow GM corn in US cornfields between 1996 and 2013.

KAEBbcVO_graph

(i)

Calculate the change in insecticide use between 1996 and 2010.

(2)

(ii)

Describe what the data shows about insecticide use and the percentage of corn fields used to grow GM corn between 1996 and 2013.

(2)

3c
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2 marks

One way in which the corn in part (b) has been genetically modified is to provide the corn with resistance to pests.

Explain one benefit of pest resistant GM corn.

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1a
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4 marks

Scientists have developed genetically modified (GM) crops in order to increase food production by increasing crop yields.

Some GM crops are described as transgenic.

(i)
Explain what is meant by the term transgenic.

(2)

(ii)

Give the role of two named enzymes in the production of GM organisms.

(2)

1b
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4 marks

Some GM crops that are available to farmers are resistant to herbicides (weedkillers).

Other GM crops are resistant to diseases caused by viruses and to damage by insects.

Some people support the use of GM crops because they may be beneficial to ecosystems.

Some people oppose the use of GM crops because they could harm ecosystems.

Discuss these opinions for and against the use of GM crops.

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2a
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4 marks

The diagram shows the process of genetic modification used to produce multiple copies of a protein from a desired gene.

~kBTm4Cw_e-3a

Identify structures W-Z in the diagram using the words below. Note that more words have been provided than are needed.

Recombinant DNA     DNA Ligase      Transgenic organism     

Bacterial plasmid      Desired gene      Insulin protein      

2b
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1 mark

Identify the vector used in this genetic modification process.

2c2 marks

The enzyme used at both W and X in the diagram in part (a) is a restriction enzyme.

Describe the role of the restriction enzyme at W and X.

2d
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2 marks

Describe what needs to happen to structure Z in part (a) in order to produce many copies of the protein coded for by the desired gene.

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3a
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3 marks

The process of genetic modification involves the use of enzymes that cut DNA.

(i)

Name the enzymes that are used to cut DNA.

(1)

(ii)

Explain why the enzymes named in part (i) are so useful in genetic modification.

(2)

3b
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3 marks

Genes can be extracted from other species and inserted into crop plants. For example, a gene that codes for the bacterial toxin known as Bt provides resistance to insect pests in crops.

(i)

Other than pest resistance, give two reasons for inserting genes from other species into crop plants.

(2)

(ii)

Suggest why inserting DNA into plant cells can be a challenge.

(1)

3c
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2 marks

Some environmentalists are concerned about inserting Bt toxin genes into crop plants.

Suggest why some are concerned about the insertion of genes from other species, such as the gene for Bt toxin, into crop plants.

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4a
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3 marks

Plants can be genetically modified (GM) to produce insect poison.

They are modified using a bacterium called Agrobacterium.

This bacterium has a plasmid that contains recombinant DNA.

Describe how the plasmid is modified to contain recombinant DNA.

4b
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6 marks

A farmer can use either of these methods to improve his crop yield.

  • Grow GM plants that produce the insect poison
  • Grow non-GM plants and use pesticides

The farmer decides to grow the GM plants rather than using pesticides.

Discuss the decision made by the farmer.

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1a
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2 marks

Insulin is a hormone that is used to treat people with type 1 diabetes. 

Describe the function of insulin in the body.

1b
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4 marks

The insulin used by diabetic patients is produced by genetically modified bacteria. 

Describe the process used to create bacteria that contain the gene for human insulin. 

1c
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2 marks

Before the process in part (b) was developed, insulin for the treatment of diabetes could only be obtained from sheep and pigs.

Suggest two reasons, other than preventing the exploitation of animals, why it is better to obtain insulin by genetic engineering than from animals.

1d
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6 marks

After the bacteria have been genetically modified they are placed in a machine called a fermenter where they can reproduce asexually and increase the number of genetically modified bacteria in the culture. 

Bacteria reproduce by dividing into two identical cells. The species of bacteria used in this process has a division time of 30 minutes.  

(i)

One genetically modified bacterial cell is added to a fermenter.

Calculate the number of bacteria that will be present in a fermenter after four and a half hours.

(3)

(ii)

Describe how conditions inside the fermenter could be controlled to maximise the reproduction of genetically modified bacteria.

(3)

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2a
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4 marks

Hepatitis B is a viral infection that can be deadly in some cases. 

There is a vaccine to prevent infection with hepatitis B that is produced from genetically modified (GM) yeast cells.

The process of producing these GM yeast cells is outlined in the diagram below.

producing-hep-b-vaccine--1

(i)

Identify the new protein produced by the yeast cells in the fermentation tank.

(1)

(ii)
Explain why the protein identified in part (i) is needed in order to produce the vaccine.

(3)

2b
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2 marks

Explain why enzyme 1 is used to cut both the desired gene and the plasmid DNA in the process shown in part (a).

2c
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2 marks

One mechanism by which the hepatitis B virus can be transmitted is from an infected mother to their baby. This can lead to the infant developing what is known as a chronic hepatitis B infection after birth.

One way of reducing the risk of chronic infection in infants is the use of a hepatitis B vaccine. These vaccines can be produced using proteins produced by yeast cells, as shown in part (a) above, or using proteins isolated from the blood plasma of individuals who have previously been infected with hepatitits B.

Suggest two advantages of producing heptatitis B vaccines using yeast-derived protein rather than plasma-derived protein.

2d
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7 marks

The efficacy of yeast-derived and plasma-derived hepatitis B against chronic heptatitic B infection in infants was studied.

Some of the results are shown in the graph below.

Types of vaccine hepatitits B GM yeast graph SQ

(i)

Calculate the percentage increase in infants with chronic heptatitis B, for infants given the plasma-derived vaccine, between 1 and 9 months.

(2)

(ii)

Describe the effect of the GM yeast-derived vaccine compared to the effect of the plasma-derived vaccine on chronic hepatitis B in infants.

(3)

(iii)
Suggest a reason for the trend in infants with chronic hepatitis B between age 0-18 months. Use the information provided in part (c) and your own reasoning in your answer.
(2)

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3a
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6 marks

As part of a global scientific push to improve the efficiency and sustainability of agriculture, scientists have developed a transgenic pig. The process used to create the transgenic pig, known as 'Enviropig', is summarised below.

  1. Genes are taken from E. coli bacteria and also from mice.
  2. The combined E. coli and mouse genes are inserted into a fertilised pig egg cell nucleus using a microscope and a very small, sharp, pipette.
  3. The newly modified egg cell divides and develops into an embryo.
  4. The embryo is implanted into the uterus of a surrogate pig and allowed to develop to maturity.
  5. The resulting piglet is a transgenic 'Enviropig' that is able to produce E. coli and mouse proteins.
(i)

Explain why a plasmid vector is not a suitable way of inserting the desired genes into the fertilised pig egg cell in step 2.

(2)

(ii)

Explain why all of the cells in the pig embryo that develops in step 3 contain the new genes.

(2)

Separate: Biology Only

(iii)

Use your knowledge of the role of DNA to explain why the piglet in step 5 is able to produce E. coli and mouse proteins.

(2)

3b
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5 marks

The genes inserted into the genome of 'Enviropig' allow pigs to produce an enzyme called phytase in their saliva. Phytase enables the pigs to digest phosphorus, a mineral that is required in the diet of pigs, but that would otherwise be egested by pigs in their faeces.

Pigs that are unable to produce their own phytase need to take phytase supplements in their food, and still egest a large amount of phosphorus in their waste.

Note that phosphorus is a mineral often found in industrial fertilisers.

Use the information provided and your own knowledge to discuss the potential benefits of 'Enviropig'.

3c
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5 marks

The graph below shows the phosporus levels in the faeces of pigs with different percentages of soybean meal in their diet.

soybean-meal

(i)

Calculate the percentage decrease in faecal phosphorus between non-transgenic and transgenic pigs on a diet of 54 % soybean meal.

(2)

(ii)
Describe what the results show about the impact of the addition of the new genes on faecal phosphorus in pigs. Avoid repeating any data points used in part (i).

(3)

3d
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3 marks

An environmental science student read the results of the study shown in part (c) and reached the following conclusion:

"In the future, 'Enviropigs' will provide a solution to the sustainability issues around pig farming worldwide"

Evaluate the student's conclusion.

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