Genetically Modified Organisms in Agriculture (CIE A Level Biology)

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.

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.

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

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.

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.

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.

Fig. 1

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

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.

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

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

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).

Fig. 1

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

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

Suggest why this was done.

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

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.

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

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

AquaAdventure Salmon is a form of genetically modified salmon that has become available to consumers in the USA.

Table 1 shows some data presented to the US Food and Drug Authority to promote approval of the GM salmon.

Table 1

Calculate how much faster a 1 kg fish can be produced from a GM salmon compared to a non-GM salmon.

Assume that their mass at birth is negligible.

[3]

(ii)

Calculate the difference in daily feed requirements of a 1 kg non-GM salmon compared to a 1 kg GM salmon.

Give your answer in g day^-1.

[2]

AquaAdventure also reported that the GM salmon produced showed evidence of increased resistance to common diseases affecting non-GM salmon.

Discuss the benefits of this to the producer.

Critics of AquaAdventure argue that there is a risk that GM salmon may escape into the wild and breed with wild fish stocks.

Explain why this may be of concern.