21. Biotechnology and genetic modification
A section of Biology, 0610
Listing 10 of 260 questions
Yeast can respire aerobically and anaerobically. State the balanced chemical equation for aerobic respiration by yeast. When yeast respires anaerobically, ethanol is released. Ethanol is a type of sustainable resource that can be produced from a wide range of crops. It can be used as a biofuel. Table 5.1 summarises some information about crops that are used to make biofuel. Table 5.1 crop biofuel produced energy yield / GJ per ha optimum growth temperature / °C optimum annual rainfall range / mm wheat ethanol 53–84 800–1200 corn ethanol 63–76 360–1000 sugar beet ethanol 110–122 360–1000 sugar cane ethanol 110–140 800–1200 oil palm oil 150–166 1100–2500 Uruguay has an average temperature range of 12 °C to 24 °C and an average annual rainfall of 1000 mm. Suggest and explain which crop would be the most suitable crop to grow for producing biofuel in Uruguay. Use the information in Table 5.1 to justify your choice. Sugar cane requires soil with high concentrations of nitrogen and potassium. Describe how the lack of nitrate ions would affect the production of sugar cane. Researchers in Brazil are considering using microscopic algae that live in water to produce biofuels. They have found that algae can produce a maximum amount of energy of 200 GJ per m2. 1 m2 = 0.0001 ha Convert the production of biofuel from algae into GJ per ha. Space for working. GJ per ha Suggest why people who are concerned about the environment want countries to produce more biofuel from algae rather than the crops listed in Table 5.1. Define the term sustainable development.
0610_w17_qp_41
THEORY
2017
Paper 4, Variant 1
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A factory uses biotechnology to process apples. Some of the apple juice is mixed with yeast and used to make ethanol. State the type of respiration in yeast that produces ethanol. State the name of the substance in apple juice that is converted to ethanol by yeast. The yeast uses enzymes to produce ethanol. Define the term enzyme. shows apparatus used to find the best temperature for making ethanol. yeast and apple juice stop-clock bubbles of gas water The same apparatus was used at different temperatures. The rate of ethanol production was compared by counting the number of bubbles of gas produced by the yeast and apple juice mixture per minute. State the name of the gas produced by the yeast in . The results of the investigation are shown in . rate of reaction / bubbles per minute temperature / °C Calculate the increase in the rate of reaction from 20 °C to 25 °C in . Space for working. bubbles per minute State the optimum temperature for the reaction shown in . °C The cut surface of an apple usually turns brown when exposed to air. This is caused by enzymes. Three slices of apple were given different treatments and were then exposed to air for 30 minutes. Table 6.1 shows the treatments and appearance of the apple slices. Table 6.1 apple slice pH temperature / °C appearance of the apple slice at 0 minutes appearance of the apple slice after 30 minutes A white brown B white white C white white Suggest why slice B and slice C did not turn brown after 30 minutes. slice B slice C The enzyme pectinase is used in industry for the production of apple juice. Explain why pectinase is used when making apple juice. Hygienic conditions are required in an apple juice factory. Describe three precautions workers should take to ensure that good food hygiene is maintained in the apple juice factory.
0610_w18_qp_33
THEORY
2018
Paper 3, Variant 3
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Yeast cells have many structures in common with a plant cell. is a drawing of a yeast cell. A B C D cell wall State the names of the cell structures labelled A and D on . A D State the functions of the cell structures labelled B and C on . B C State the name of one structure that is found in plant cells but is absent in yeast cells. Yeast is used in the production of ethanol to manufacture a type of biofuel. is a flow chart of the process. maize plants maltose enzyme S enzyme T process U in anaerobic conditions glucose extraction of starch from maize ethanol carbon dioxide State the names of enzymes S and T. S T Yeast is used in process U. Complete the balanced chemical equation for anaerobic respiration in yeast. C2H5OH + Suggest the advantages of using biofuels instead of fossil fuels. Carbon dioxide may be collected from process U and sold for use in glasshouses. Explain why carbon dioxide is used in glasshouses.
0610_w20_qp_42
THEORY
2020
Paper 4, Variant 2
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Yeast is an example of a single-celled fungus. The population of yeast can be estimated by using a light microscope to view a small sample of yeast cells in a modified microscope slide. There is a square chamber, with a specific volume, cut into the microscope slide and a grid to make it easier to count the number of cells. shows a diagram of the modified microscope slide. It also shows part of a light microscope with the modified microscope slide filled to the top with a sample of yeast cells. grid chamber The length of the sides of each small square in the grid in the modified microscope slide is 200 μm. The depth of the chamber is 100 μm. There is a total of 25 small squares in the grid. Each small square in the grid has an average of 52 yeast cells. Calculate the concentration of yeast cells per mm3. Space for working. cells per mm3 A small sample of yeast cells and 19 g per dm3 of sugar were added to a fermenter. The population size of live yeast cells and the concentration of the sugar in the fermenter were calculated every day for 10 days. The results are shown in and . time / days concentration of sugar / g per dm3 time / days population size of live yeast cells Draw an X on to indicate the position of the lag phase. Complete the line on to show the expected change in the population size of live yeast cells from day 3 to day 10. Describe and explain the changes in the concentration of sugar in the fermenter over the 10-day period. Explain why it is important that there is a tube in the fermenter that allows gases to escape.
0610_w20_qp_43
THEORY
2020
Paper 4, Variant 3
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Questions Discovered
260