19.3. Genetically modified organisms in agriculture
A subsection of Biology, 9700, through 19. Genetic technology
Listing 10 of 27 questions
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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Genetic technology involving the creation of recombinant DNA can be used to treat different human diseases. These include diseases such as diabetes that may have multiple causes and inherited disorders that are caused by a single gene. Outline two different ways of using recombinant DNA technology to treat these diseases. diabetes single gene disorder A new application of recombinant DNA technology uses the genetic modification of a plant to prevent disease. It aims to prevent the most common source of food-borne disease, which is caused by eating food contaminated with pathogenic Escherichia coli bacteria. Scientists genetically modified edible spinach plants to produce colicins. Colicins are antimicrobial proteins that can kill pathogenic E.coli. Colicins are normally made by other bacteria. An experiment was carried out to test this application by spraying an extract of genetically modified (GM) spinach in buffer solution onto raw meat contaminated with pathogenic E.coli. The meat was stored at 10 °C for varying lengths of time before the numbers of viable pathogenic E.coli bacteria were counted. shows the results. time stored at 10 °C / hours log number of viable bacterial cells per gram of meat no treatment Key: buffer solution only buffer solution plus GM spinach extract With reference to , evaluate the effectiveness of using GM spinach spray on raw meat to prevent food-borne disease. Regulatory authorities may not approve the use of GM spinach spray on raw meat to protect consumers. Discuss the concerns that may stop regulatory authorities approving this application of recombinant DNA technology.
9700_s21_qp_42
THEORY
2021
Paper 4, Variant 2
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Bt maize has been genetically engineered to resist insect attack. In 2019, Bt maize formed 83% of the maize grown in the USA. Outline how the genetic engineering process produced Bt maize plants with resistance to insect attack. A proposed conservation benefit of Bt maize is that, unlike chemical insecticide sprays, it should not harm non‑target insects. When Bt maize was first grown in the USA, scientists were concerned that maize pollen containing the Bt toxin might be deposited by the wind on wild plants such as milkweeds, Asclepias spp. Milkweed leaves are the food source of caterpillars of the monarch butterfly, Danaus plexippus. In 1999, a laboratory experiment tested the effects of feeding milkweed leaves treated in different ways to the caterpillars of monarch butterflies. Each group of caterpillars was provided with milkweed leaves to eat throughout the experiment. The three different treatments were: • leaves with no pollen • leaves dusted with pollen from non‑Bt maize • leaves dusted with pollen from Bt maize. shows the results of this laboratory experiment. time / days percentage survival of monarch caterpillars leaves with no pollen Key: leaves with pollen from non-Bt maize leaves with pollen from Bt maize State what can be concluded from . Laboratory results are not always useful in predicting what will happen in real ecosystems. • Some scientists predicted that increasing the area of Bt maize in the USA would decrease the number of monarch butterflies, based on the results in . • More monarch butterflies were counted in 2019 than in 1999, even though the quantity of Bt maize grown more than tripled. Suggest reasons why the predicted decrease in the number of monarch butterflies did not occur in the real ecosystem.
9700_s21_qp_43
THEORY
2021
Paper 4, Variant 3
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Explain the advantages to a plant species of cross-pollination compared to self-pollination. Some of the most important food plants for humans depend on insect pollinators, such as the honeybee, Apis mellifera. shows a honeybee. A study was carried out in 2006 to show how four food crops are pollinated. shows the results of this study. almond apple orange plant peach pollinated by honeybee pollinated by other insects pollinated by birds / wind / rainwater Key number of plants pollinated The populations of honeybees in some parts of the world have declined in recent years. With reference to , explain which crop will be most affected and which crop will be least affected by the decline in honeybees. most affected least affected Suggest reasons why honeybee populations have declined.
9700_w12_qp_43
THEORY
2012
Paper 4, Variant 3
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Atlantic salmon, Salmo salar, is one of the most important fish species farmed for human consumption. shows an Atlantic salmon. Infectious pancreatic necrosis (IPN) is a serious viral disease currently affecting farmed salmon. Describe how artificial selection could be used to produce a population of salmon that is resistant to IPN. Suggest problems that may arise from artificial selection. A laboratory investigation was carried out to compare the artificially selected farmed Atlantic salmon with farmed salmon that had not been artificially selected. Three groups of young fish were set up in carefully controlled conditions as follows: • Group A: artificially selected salmon • Group B: non-artificially selected salmon • Group C: non-artificially selected salmon. During this investigation, only groups A and B were exposed to IPN on day 0. The percentages of salmon that died (percentage mortality) were calculated and are shown in .                    WLPHGD\V JURXS% JURXS$ JURXS& SHUFHQWDJH PRUWDOLW\ Describe and explain the differences in percentage mortality between groups A and B. Suggest a reason for the mortality in group C.
9700_w15_qp_43
THEORY
2015
Paper 4, Variant 3
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Questions Discovered
27