19. Genetic technology
A section of Biology, 9700
Listing 10 of 107 questions
Gene technology has many uses including the production of substances such as insulin. Outline what is meant by gene technology. Explain why genes for enzymes that produce fluorescent substances are used as makers in gene technology. There is much controversy throughout the world regarding the use of genetically modified (GM) crops. Suggest two advantages of growing GM rice with an enhanced vitamin A content. Suggest two disadvantages of growing GM crops.
9700_s10_qp_43
THEORY
2010
Paper 4, Variant 3
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Oil seed rape , Brassica napus, has been genetically modified to be resistant to herbicides containing glufosinate ammonium. The genetically modified (GM) oil seed rape contains the bar gene, obtained from a soil bacterium. This gene codes for an enzyme that converts glufosinate ammonium into a non-toxic compound. Outline the advantages to farmers of growing glufosinate-resistant oil seed rape. The bar gene was introduced into the oil seed rape using plasmids. The plasmids also contained a promoter taken from thale cress, Arabidopsis thaliana. Outline the structure of a plasmid. Explain how the properties of plasmids make them suitable for use during genetic modification programmes. Describe the role of a promoter in gene expression. The pollen of oil seed rape is transferred from one flower to another by insects. After pollination, fertilisation and seed formation can occur. One of the potential problems of growing glufosinate–resistant oil seed rape is that pollen from these plants could be transferred to the flowers of wild relatives, such as wild radish, Raphanus raphanistrum. This could result in genetic changes in these wild species. An experiment was carried out to investigate whether glufosinate–resistant hybrids between GM oil seed rape and wild radish plants are likely to compete successfully with non-hybrid or non-resistant plants in the natural environment. • Type 1 hybrids were produced by transferring pollen from wild radish (diploid number 18) to glufosinate–resistant oil seed rape (diploid number 38). • Type 2 hybrids were produced by transferring pollen from glufosinate–resistant oil seed rape to wild radish. • Each hybrid was then crossed with wild radish over several generations. • The resulting offspring were then grown in field trials, together with normal wild radish. • The height of the plants and number of seeds each produced were measured. Then the plants were tested for the bar gene. Table 3.1 shows the results. Table 3.1 type of plant number of seeds per plant mean height / cm presence of bar gene offspring from type 1 hybrid and wild radish 22.3 absent 28.3 present offspring from type 2 hybrid and wild radish 88.7 absent 95.0 present wild radishes 76.5 absent Predict the diploid number of chromosomes in a hybrid between oil seed rape and wild radish. Suggest how the researchers could have determined whether or not the bar gene was present in the plants. Many varieties of GM oil seed rape are male sterile, meaning that they do not produce pollen. With reference to Table 3.1, suggest the advantages to the environment of growing male sterile varieties of GM oil seed rape, rather than GM varieties that produce pollen.
9700_s17_qp_41
THEORY
2017
Paper 4, Variant 1
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Oil seed rape , Brassica napus, has been genetically modified to be resistant to herbicides containing glufosinate ammonium. The genetically modified (GM) oil seed rape contains the bar gene, obtained from a soil bacterium. This gene codes for an enzyme that converts glufosinate ammonium into a non-toxic compound. Outline the advantages to farmers of growing glufosinate-resistant oil seed rape. The bar gene was introduced into the oil seed rape using plasmids. The plasmids also contained a promoter taken from thale cress, Arabidopsis thaliana. Outline the structure of a plasmid. Explain how the properties of plasmids make them suitable for use during genetic modification programmes. Describe the role of a promoter in gene expression. The pollen of oil seed rape is transferred from one flower to another by insects. After pollination, fertilisation and seed formation can occur. One of the potential problems of growing glufosinate–resistant oil seed rape is that pollen from these plants could be transferred to the flowers of wild relatives, such as wild radish, Raphanus raphanistrum. This could result in genetic changes in these wild species. An experiment was carried out to investigate whether glufosinate–resistant hybrids between GM oil seed rape and wild radish plants are likely to compete successfully with non-hybrid or non-resistant plants in the natural environment. • Type 1 hybrids were produced by transferring pollen from wild radish (diploid number 18) to glufosinate–resistant oil seed rape (diploid number 38). • Type 2 hybrids were produced by transferring pollen from glufosinate–resistant oil seed rape to wild radish. • Each hybrid was then crossed with wild radish over several generations. • The resulting offspring were then grown in field trials, together with normal wild radish. • The height of the plants and number of seeds each produced were measured. Then the plants were tested for the bar gene. Table 3.1 shows the results. Table 3.1 type of plant number of seeds per plant mean height / cm presence of bar gene offspring from type 1 hybrid and wild radish 22.3 absent 28.3 present offspring from type 2 hybrid and wild radish 88.7 absent 95.0 present wild radishes 76.5 absent Predict the diploid number of chromosomes in a hybrid between oil seed rape and wild radish. Suggest how the researchers could have determined whether or not the bar gene was present in the plants. Many varieties of GM oil seed rape are male sterile, meaning that they do not produce pollen. With reference to Table 3.1, suggest the advantages to the environment of growing male sterile varieties of GM oil seed rape, rather than GM varieties that produce pollen.
9700_s17_qp_43
THEORY
2017
Paper 4, Variant 3
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Pigs are farm animals used for livestock in some parts of the world. The first genetically modified pigs were produced in 1985. Foreign DNA was injected directly into the nuclei of zygotes. The foreign DNA was made up of two components: • the gene coding for human growth hormone • a section of mouse DNA that, in the presence of metal ions, allows transcription to begin. The human growth hormone synthesised by the transgenic pigs had the effect of making the pigs grow faster, larger and heavier than non-genetically modified pigs. Suggest reasons for this difference. Suggest and explain why the mouse DNA was included in the foreign DNA. Only 1% of the attempts successfully produced transgenic pigs. These pigs showed higher body mass and a greater muscle to fat ratio than normal pigs. Monitoring of the pigs’ behaviour revealed that they rested more than normal pigs, suffered from stomach ulcers and were unwilling to mate. Discuss whether these transgenic pigs have long term economic value. Comment on the ethics of producing transgenic pigs showing the features described. In 2015 pigs were produced that had part of their genome altered by a new technique. The technique involved: • an RNA sequence designed to bind to a specific targeted pig gene • a gene-editing enzyme that is able to cut out sections of DNA. The technique was used on pig zygotes that had been created by IVF. All the zygotes treated grew into piglets and these all showed large deletions in the targeted gene. This gene coded for a specific cell surface membrane protein. The piglets did not express the protein and this gave them resistance to infection by a virus that causes a serious disease in pigs. Describe two advantages of the gene-editing technique compared to the traditional genetic modification technique used to make transgenic pigs in 1985. A scientist stated that this new technique is a form of selective breeding, so is not genetic engineering. Discuss whether this statement is true and whether public groups who oppose transgenic animals will be more or less likely to accept the new technique.
9700_s18_qp_41
THEORY
2018
Paper 4, Variant 1
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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. 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 6.1 shows the results of this modelling for four countries. Table 6.1 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 6.1 suggests about the social and ethical implications of growing GM maize.
9700_s19_qp_41
THEORY
2019
Paper 4, Variant 1
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Soybean, Glycine max, is an important food crop for human consumption and for feeding to animals. Two varieties of soybean are Vinton 81 and GTS 40-3-2. Vinton 81 has been developed in the traditional way by selective breeding (artificial selection) and GTS 40-3-2 is an example of a genetically modified (GM) organism. GTS 40-3-2 is described as herbicide-resistant, as it can withstand the application of glyphosate herbicide. Glyphosate is sprayed on the crop to kill weeds. Outline how genetic engineering gave GTS 40-3-2 the trait of herbicide resistance. Countries vary in the extent to which they grow GM varieties, such as GTS 40-3-2, instead of traditional varieties such as Vinton 81. • In the USA, 94% of soybeans grown are GM. • In Europe, 0% of soybeans grown are GM. Scientists used computer models to predict the effect of two different changes in agricultural practice on soybean crop yields: • a global ban that reduces the cultivation of GM soybeans to 0% everywhere • all countries increasing the cultivation of GM soybeans to the 94% level of the USA. Table 3.1 shows the results of this modelling for four countries. Table 3.1 country percentage change in yield of soybeans decrease GM soybean cultivation to 0% of total increase GM soybean cultivation to 94% of total Argentina 0.00 +6.23 Bolivia –10.82 0.00 Brazil 0.00 +6.23 USA –5.87 0.00 Explain what the data in Table 3.1 suggests about the social and ethical implications of growing GM soybeans.
9700_s19_qp_42
THEORY
2019
Paper 4, Variant 2
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Rice, Oryza sativa, is an important food crop for human consumption. Two varieties of rice are T2A-1 and Shanyou 2. Shanyou 2 has been developed in the traditional way by selective breeding (artificial selection) and T2A-1 is an example of a genetically modified (GM) organism. T2A-1 rice is described as insect-resistant as it produces a chemical that is toxic to insect pests. Outline how genetic engineering gave T2A-1 rice the trait of insect resistance. Countries vary in the extent to which they grow GM varieties instead of traditional crop varieties. • The USA, Canada and countries in South America plant GM varieties on a large proportion of their crop-growing land, reaching 94% for soybeans in the USA. • In most European countries, 0% of the crop-growing land is planted with GM varieties. Scientists used computer models to predict the effects of a global ban that reduced the cultivation of GM crops to 0% everywhere. Table 4.1 shows the results of this modelling on world crop yields and the purchase price of each crop. Table 4.1 crop percentage change in crop yield percentage change in purchase price rapeseed –0.14 +1.96 rice –0.12 +1.58 soybeans –1.40 +4.05 Explain what the data in Table 4.1 show about the social implications of growing GM crops. A worldwide ban on growing GM crop varieties would mean that more land would be needed to grow traditional crops, such as Shanyou 2. This would involve converting forest and grassland to crop-growing land. Table 4.2 shows the predicted changes in carbon dioxide emissions associated with this change in use of land. Table 4.2 change in use of land change in carbon dioxide emissions / million kg CO2 forest to crop-growing land + 608 726 grassland to crop-growing land + 276 042 Discuss what the data in Table 4.2 indicate about the environmental implications of growing GM crops.
9700_s19_qp_43
THEORY
2019
Paper 4, Variant 3
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Genetic engineering involves the manipulation of naturally occurring enzymes and processes. List the enzymes used in genetic engineering (genetic modification) and outline their roles in natural processes. Genetically modified organisms (GMOs) include crop plants. Genetically modified (GM) crop plants have been grown in North America in increasing quantities since 1996. They are now grown in many areas of the world and are eaten by millions of people and farm animals. Table 4.1 compares the area of land used to grow GM crop plants on six continents in 2013. Table 4.1 continent area of land used to grow GM crop plants / million hectares edible GM crop plants grown Africa 3.5 maize, soybean Asia 19.1 maize, papaya, tomato Australasia 0.6 canola Europe 0.2 maize North America 81.1 canola, maize, papaya, soybean, squash, sugar beet South America 70.9 canola, maize, soybean Suggest how North America and South America benefit from growing large areas of GM crop plants rather than non-GM crop plants. Only a small area of land is used to grow GM crop plants in Europe. This is mainly because most of Europe uses a ‘precautionary principle’. The precautionary principle prevents GM crop plants being grown if there is a possible risk of harm to human health or to the environment, even if there is no proof of harm. Many European citizens have concerns about the safety of eating GM food, but Europe imports large quantities of GM maize and GM soybean to feed farm animals. Use this information and Table 4.1 to deduce two arguments in favour of growing more GM crop plants in Europe. Explain why the data in Table 4.1 are not enough to calculate the extent to which different continents have replaced traditional crop plants with GM versions.
9700_s21_qp_41
THEORY
2021
Paper 4, Variant 1
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In 1973 a technique for genetic engineering was used for the first time. Recombinant DNA was made using a plasmid and this was successfully transferred into an organism. In 2012 a new technique for genetic engineering, called gene editing, was developed. Table 4.1 lists some statements about the two genetic engineering techniques. Complete Table 4.1 to compare the original genetic engineering technique using a plasmid vector with the newer technique of gene editing. For each row, place a tick (3) in the correct column if the statement applies and leave a blank if the statement does not apply. Table 4.1 statement genetic engineering using a plasmid gene editing It can produce a transgenic organism. It can modify the characteristics of an organism. It can delete unwanted DNA. It uses an enzyme that cuts DNA. It can use RNA to precisely locate the target gene. Orange trees, Citrus sinensis, produce fruits that are an important food crop. The functional leaf area of orange trees may be reduced by the growth of citrus canker bacteria. These bacteria cause citrus canker disease. Scientists used gene editing to develop two types of orange tree with different mutations (changes to the DNA). The mutant orange tree leaves showed resistance to citrus canker disease. shows the area of leaf with citrus canker disease in wild type (not gene edited) and gene edited orange tree leaves after they have been exposed to citrus canker bacteria. 0.0 1.0 2.0 area of leaf with canker disease / mm2 3.0 0.5 1.5 2.5 3.5 A B C type of orange tree Identify the letter that represents the wild type orange trees on . Explain the social benefits of this example of gene editing.
9700_s22_qp_41
THEORY
2022
Paper 4, Variant 1
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Questions Discovered
107