Genetic Modification (Edexcel GCSE Combined Science: Biology): Exam Questions

Higher Tier only

Name, and describe the roles of, the main enzymes used in genetic engineering.

Genes from the bacterium Bacillus thuringiensis can be extracted and inserted into crop plants.

Explain the benefit of this example of genetic engineering to farmers. 

Genetic engineering changes the genome of a species more extensively than selective breeding.

Suggest why. 

Figure 1 shows a selectively-bred bull from the variety of beef cattle known as the Belgian blue.

Figure 1

Use your knowledge of selective breeding to suggest two benefits and two drawbacks of breeding from the bull shown in Figure 1. 

The owner of the bull shown in Figure 1 is able to extract the bull's semen and sell that to other cattle breeders to allow their cows to become pregnant with this bull's offspring. This practice is called artificial insemination (AI). 

State one advantage of farmers using AI during selective breeding. 

Higher Tier only

Explain the meaning of the term 'vector' when used in genetic engineering. 

Higher Tier only

The table in Figure 5 sets out a number of steps in the production of human insulin in a process involving genetically-engineered bacteria. 

The statements are in the wrong order. 

Figure 5

Complete the table in Figure 6 to list the steps in the correct sequence.

The first step has been completed for you. 

Figure 6

Higher Tier Only

Yeast cells can be genetically modified to produce a painkiller.

This painkiller is usually obtained from opium poppies.

One method for genetically modifying a yeast cell uses a plasmid containing the desired gene.

(i) Explain how a gene can be inserted into a plasmid.

(2)

(ii) Discuss the possible benefits and risks of producing painkillers from genetically modified yeast cells rather than extracting the painkillers from poppies.

(3)

Figure 1 shows two varieties of potato plant.

Figure 1

New varieties of potato plant can be produced by selective breeding.

Explain how selective breeding of the two varieties of potato plants can produce new potato plants that are all faster growing and produce many, large potatoes.

Higher Tier Only

Figure 1 shows a plasmid containing the human insulin gene.

Figure 1

Explain how the human insulin gene can be inserted into a plasmid.

Figure 1 shows some information about two types of cattle.

Figure 1

Describe how these types of cattle could be selectively bred to produce cattle that can survive high temperatures and have good meat quality.

Figure 2 shows the leaf of a wheat plant with a fungal disease.

Figure 2

Give two benefits of breeding wheat plants that are resistant to fungal disease.

1 ....................................................

2 ....................................................

Higher Tier Only

Genetically modified (GM) crops have been on the market since the 1990s. This biotechnology involves changing the DNA of one organism, often by inserting genes from another.

GM maize makes up more than 87% of all maize grown in the United States. The maize has been modified to contain the pesticide Bt, making it toxic to insects that try to eat it. The gene that makes Bt comes from the bacterium Bacillus thuringiensis, which produces a toxin that kills insects. 

(i) Describe how the gene can be transferred from the bacterium, Bacillus thuringiensis, to the maize crop.

(3)

(ii) Explain why farmers might want to grow GM crops that are resistant to pests.

(3)

Figure 1 shows the number of Bt crops and the number of resistant species in an 80 hectare farm in the United States.

Figure 1

(i) Calculate the percentage increase in Bt crops from 2011 to 2022.

(2)

(ii) Explain the pattern shown by the data in the graph.

(5)

Discuss why some people might disagree with the production of genetically modified crops.

Higher Tier Only

Recent studies have shown that cancerous tumours can be targeted using genetically engineered bacteria. Research has shown that where chemotherapy and radiotherapy have been unsuccessful in treating cancerous tumours, the answer may lie with the use of bacteria as a therapeutic agent.

A group of bacteria, called Clostridium, can be modified with a gene that causes the bacteria to produce proteins which have been shown to destroy tumours.

(i) Explain how the Clostridium bacteria can be genetically modified to produce the tumour-destroying proteins.

(4)

(ii) Recent studies carried out on mice showed that genetically modified bacteria, when applied to the skin of mice infected with skin cancer, were successful in slowing or preventing the growth of 15 out of 16 cancerous tumours. 

A scientist has concluded that genetically engineered bacteria is the most effective treatment for cancer.

Suggest two reasons why this conclusion may not be valid.

(2)

Selective breeding is another method used by humans so that organisms have desirable characteristics, such as selectively breeding cows to produce large volumes of high-quality beef.

The graph in Figure 1 shows information about the mass of beef produced by cattle in Ireland from 2012 to 2022. 

Figure 1

(i) Give the mean mass of beef produced from 2012 to 2022.

Give your answer in tonnes in standard form. 

(2)

(ii) Suggest why traits such as producing more beef might not have developed due to natural selection.

(3)

(iii) Explain two disadvantages of selectively breeding cows to produce more beef. 

(2)

Some people believe that selective breeding can cause issues with inbreeding. 

The pug is an ancient breed of dog which, in recent years, has suffered from issues caused by inbreeding. 

Figure 2 shows data collected about heart failure in pugs over a 12 month period in Boston, USA.

Figure 2

(i) Describe how the incidence of heart failure in pugs changed from January to December. 

Use data from Figure 2 in your answer.

(2)

(ii) Other than the risk of heart failure, give one other reason why people might disagree with selectively breeding pugs.

(1)

Evaluate the benefits and risks of genetic engineering and selective breeding in modern agriculture.

You should include the practical and ethical implications in your answer.