CIE A Level Biology

Topic Questions

A LevelBiologyCIETopic Questions19. Genetic Technology19.3 Genetically Modified Organisms in Agriculture

Syllabus Edition

First teaching 2020

Last exams 2024

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19.3 Genetically Modified Organisms in Agriculture

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1a
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Describe how genetic engineering can assist farmers in meeting the world's food demands.

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1b
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The use of genetically modified organisms (GMOs) in food production is associated with a number of social and ethical issues. 

State three social and/or ethical implications of using GMOs in food production. 

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1c
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In March 2023 England, UK passed the Genetic Technology Act into law. This means that food with edited genes can be developed commercially. Labelling of gene-edited food is not a requirement and there is concern that genetically modified food may enter other parts of the UK, such as Wales and Scotland.

Suggest why a lack of clear labelling is an ethical concern for some people.

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2a
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Salmon is an example of a farmed food organism that has been genetically engineered. 

(i)

State how salmon have been altered using genetic engineering.

[1]

(ii)
Explain how the alteration in part (i) is beneficial to salmon farmers.

[1]

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2b
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State how salmon farmers ensure that the new gene inserted into the GM salmon does not enter wild salmon populations. 

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2c
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A scientist investigated a gene (GH) that codes for a growth hormone. They inserted copies of the GH gene into plasmids. They then microinjected these recombinant plasmids into fertilised egg cells from farmed salmon. The aim of the investigation was to determine whether or not the transferred GH gene increased the growth of salmon.

The scientists carried out the investigation as follows:

  • The scientist microinjected 3 000 fertilised egg cells with the GH plasmid and left 3 000 fertilised egg cells untreated.
  • After 12 months they determined the mean mass of the genetically engineered salmon and non-genetically engineered fish.

The results the scientist obtained are shown in Table 1.

Table 1

Type of salmon Mean mass of salmon / g 
Genetically engineered 1.85 
Non-genetically engineered  0.63 

Use the data in Table 1 to give a conclusion on the impact of the GH gene on the growth of salmon.

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2d
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Explain one feature of the design of the scientist's investigation that helped to ensure the validity of the experiment.

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3a
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Some species of cotton have been genetically modified to contain a gene for the Bt toxin, which is taken from the bacterium Bacillus thuringiensis.

Describe the effect that this gene modification has on these cotton plants.

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3b
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One problem that has arisen with genetic engineering of cotton plants is resistance to the Bt toxin.

Explain what is meant by resistance in this context.

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3c
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Scientists investigated resistance to a herbicide in soybean plants. They transferred a herbicide resistance gene that comes from a strain of the bacterium Agrobacterium. 

The scientists grew varieties of the soybean crop plant with and without the resistance gene. The crops were grown on farmland where the occurrence of non-crop plants (weeds) was common. Both types of soybean plants were sprayed with the herbicide glyphosate. The scientists measured the mean number of soybean plants that achieved full growth and were ready to harvest. 

Fig. 1 shows their results. soybean

Fig. 1

The scientists concluded that the presence of the resistance gene protects plants against glyphosate herbicide.

Use the data shown in Fig. 1 to explain why they came to this conclusion.

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3d
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Explain the effect of the herbicide resistant gene on soybean plants.

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1a
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Maize, Zea mays, is an important food crop for human consumption and for feeding to animals.

Two varieties of maize are MON810 and Justina. Justina has been developed in the traditional way by selective breeding (artificial selection) and MON810 is an example of a genetically modified (GM) organism.

MON810 produces a chemical that is toxic to insect pests. It is described as insect-resistant.

Outline how genetic engineering gave MON810 the trait of insect resistance.

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1b
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Countries vary in the extent to which they grow GM varieties such as MON810, instead of traditional varieties such as Justina.

  • In the USA, 88 % of the total maize that is grown is GM.
  • In most European countries, 0 % of the maize that is grown is GM.

Scientists used computer models to predict the effect of two different changes in agricultural practice on maize crop yields:

  • a global ban that reduces the cultivation of GM maize to 0 % everywhere
  • all countries increasing the cultivation of GM maize to the 88 % level of the USA.

Table 1 shows the results of this modelling for four countries.

            Table 1

country percentage change in yield of maize
decrease GM maize
cultivation to 0 % of total		 increase GM maize
cultivation to 88 % of total
Argentina –8.86 +2.90
Honduras –1.26 +16.75
Spain –3.82 +5.39
USA –7.63 0.00

Explain what the data in Table 1 suggests about the social and ethical implications of growing GM maize.

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1a2 marks

Farmers use genetic engineering to quickly introduce genes that benefit the health and value of their livestock. Protein Q is a protein that gives pigs resistance to a disease that is killing livestock. Goats can be genetically engineered to produce Protein Q in their milk. Fig. 1 shows the stages involved in the process.

genetic-engineering-agriculture-sq

Fig. 1

The zebrafish gene attached to the pig Protein Q gene in stage 2, codes for a protein that glows blue under fluorescent light.

Explain why this gene has been attached.

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1b3 marks

State the role of a promoter and suggest why a goat promoter specific to the milk gland was used instead of a pig promoter.

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1c2 marks

There are very few live births that result from the multiple embryos that are implanted. The likelihood of producing offspring from genetically modified eggs is low. Suggest one reason why few live births result from the many embryos that are implanted.

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1d1 mark

When pigs are bred on farms, it is important to ensure only unrelated pigs breed.

Suggest how genetic fingerprints might be used to do this.

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2a3 marks

Salty soils can inhibit the growth of crop plants, such as tomatoes, particularly in coastal areas. Scientists have genetically modified some species of tomato to increase their salt tolerance. Fig. 1 shows the process used to introduce a gene for a sodium-pump protein obtained from another species of plant (Arabidopsis), into the genome of tomato plants. The gene resulted in increased tolerance of the tomato plants to high salt soil, without affecting the taste or salt content of the fruit produced.

19-3-fig-2-1
Fig. 1

Describe three methods that could be used to obtain the DNA fragment which contains the gene for the sodium pump protein.

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2b2 marks

In the process shown in Fig. 1, the required gene sequence is extracted from Arabidopsis and is inserted into the tomato plant. 

Explain why the transgenic tomato plant is able to produce the sodium pump protein despite being a different species to the donor plant.

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2c4 marks

Suggest two possible ways that cells with the sodium pump gene might be selected in stage 4 of Fig. 1.

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2d2 marks

Explain the evidence from Fig. 1 that the genetically modified tomato plant cells are totipotent.

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3a3 marks

Many scientists believe that genetic engineering could help solve the global food crisis by improving the quality and productivity of farmed animals and crop plants. In 2015 AquaAdventure Salmon was approved by the US Food and Drug Authority (FDA) for human consumption.

Scientists combined a growth hormone gene from Chinook salmon (Oncorhynchus tshawytscha) with the promoter gene from a cold-water fish, Ocean pout (Zoarces americanus). Ocean pout can thrive in near-freezing waters. Fig. 1 depicts the two different types of salmon: GM salmon and non-GM salmon (both fish are 18 months old).

19-3-fig-4-1Fig. 1

Using the information above, describe and explain the main benefit of this genetic modification for the producers involved.

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3b1 mark

The GM salmon in Fig. 1 was deliberately made sterile by scientists.

Suggest why this was done.

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3c6 marks

Discuss the ethical and social implications of using genetically modified organisms (GMOs) in food production. Use at least one named example in your answer.

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