21. Biotechnology and genetic modification
A section of Biology, 0610
Listing 10 of 260 questions
Some animals produce milk to feed their offspring. Table 7.1 shows the mass of the substances found in 100 g of milk from two animals. Table 7.1 substance mass in 100 g of milk / g human milk water buffalo milk protein 1.10 4.50 fat 4.50 8.00 carbohydrate 7.50 4.90 calcium 0.03 2.00 water Calculate the mass of water in both the human milk and the water buffalo milk. Write your answers in Table 7.1. Space for working. State the name of the substance in Table 7.1 that is present in a higher concentration in human milk than in water buffalo milk. State the name of one component of a balanced diet that is missing from Table 7.1. Producing milk for offspring is a characteristic of a particular group of animals. State the name of this group of animals. State how young animals use the substances listed in Table 7.1. protein fat carbohydrate calcium water An adult eats a high-fat diet. State two health problems that could be caused by eating a high-fat diet.
0610_m18_qp_32
THEORY
2018
Paper 3, Variant 2
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For Examiner's Use There are many people in the world who are not able to digest lactose, a sugar in milk produced by cows, goats and sheep. These people do not make the enzyme lactase that breaks down lactose in the small intestine. Describe what is meant by the term enzyme. People who cannot digest lactose sometimes drink a liquid containing the enzyme lactase before they eat food containing milk products. The aim of this treatment is to digest any lactose in the food, but it is not likely to be successful. Suggest why this treatment is not likely to be successful.
0610_s11_qp_22
THEORY
2011
Paper 2, Variant 2
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For Examiner's Use Bovine somatotropin (BST) is a protein hormone that stimulates growth in cows. Name the small molecules that are joined together to make proteins. Define the term growth. Genetic engineering techniques similar to those used for producing human insulin were used to make bacteria produce BST. Outline the way in which genetic engineering was used to produce BST. For Examiner's Use The effects of BST on milk production and the food energy intake of cows were investigated. The milk yield and food energy intake were recorded each day for each cow in two groups, A and B. • Group A received BST treatment at week 10. • Group B did not receive any BST. The results are shown in . mean milk yield / kg per day time / weeks BST given mean food energy intake / MJ per day time / weeks BST given key BST no BST A B A A B B For Examiner's Use Use to describe the effect of BST treatment on mean milk yield and mean food energy intake. You will gain credit if you use data from in your answer. mean milk yield mean food energy intake Various studies have shown that there is little economic benefit from using BST. Use the results from to explain why this might be so. For Examiner's Use The US Food and Drug Administration certifies that milk from cows treated with BST is as safe as milk from cows not treated with the hormone. It is impossible to test milk to detect the use of BST, but some milk producers in the US label their milk to indicate that it is BST-free. Discuss the reasons for labelling milk to show whether it has come from cattle treated with BST or not.
0610_w13_qp_33
THEORY
2013
Paper 3, Variant 3
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Milk is sometimes referred to as a ‘complete food’ because it contains all the nutrients that a young mammal requires. Table 1.1 shows three nutrients that are contained in milk. Complete the table by stating one role of each nutrient in the body of a young mammal. Table 1.1 nutrient role in the body protein lactose (milk sugar) calcium Protein digestion begins in the stomach of the human alimentary canal and is completed in the small intestine. Describe in detail how enzymes function to digest protein in the alimentary canal. Some people are unable to digest lactose (milk sugar) and have a condition known as lactose intolerance. shows what happens in the intestine of a person who is lactose intolerant if they eat food containing a lot of lactose. from stomach build-up of gas and water small intestine large intestine bacteria produce hydrogen, methane and carbon dioxide bacteria digest lactose to simple sugars water diarrhoea and gas not to scale Key: lactose bacteria Explain why lactose is not absorbed by the small intestine. Suggest the dangers to health of severe diarrhoea if it is not treated for a long time. Hydrogen gas is produced by the bacteria that digest lactose in the large intestine. The gas is absorbed into the blood and excreted through the lungs. Lactose intolerance can be monitored by measuring the hydrogen gas content of the air a person breathes out. People taking part in an investigation into lactose intolerance consumed the following milk products on different days: A. untreated milk B. milk treated with lactase immediately before drinking C. milk treated with lactase three days before drinking D. yoghurt made by bacteria that digested the lactose in the milk The hydrogen gas content of the air breathed out was measured every hour for five hours following the ingestion of each milk product. The mean results are shown in . hydrogen gas breathed out / parts per million 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 time / hours A B C D Explain why untreated milk was included in the investigation. Suggest why lactase might be added to milk. Use the results in to explain why yoghurt is the best milk product for people with lactose intolerance.
0610_w16_qp_42
THEORY
2016
Paper 4, Variant 2
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Milk is a source of some of the nutrients that are part of a balanced diet. Calcium and protein are two nutrients found in milk. Describe the importance of calcium and protein in the diet. calcium protein Lactose is found in cows’ milk. Some people do not have the enzyme to digest lactose. State the names of two organs, associated with the alimentary canal, that produce enzymes. shows a flow diagram for the production of lactose-free milk. Step 1 collect cows’ milk from farm Step 2 heat milk to a high temperature for 15 seconds Step 3 allow milk to cool to 20°C Step 4 pour milk into a container of beads containing enzymes Step 5 collect lactose-free milk Step 6 store lactose-free milk at 2°C in sterile bottles beads containing enzyme milk diagram of Step 4 lactose-free milk Explain how heating the milk in step 2 in ensures the hygienic preparation of lactose-free milk. Explain why the milk must be cooled in step 3 before it makes contact with the enzymes. State the name of the enzyme used to make lactose-free milk in step 4. Suggest why the enzymes are kept in the beads in step 4 rather than mixed as an enzyme solution with the milk. Milk is produced by mammals. Explain the advantages to newborn mammals of breast milk. Explain why breast-feeding mothers are advised to drink plenty of water and avoid excessive alcohol consumption.
0610_w20_qp_41
THEORY
2020
Paper 4, Variant 1
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Questions Discovered
260