Biotechnology & genetic modification Banker

1. (a) Why does bread dough rise when yeast is added and the dough is left in a warm place?A Yeast produces ethanol, which evaporates and lifts the dough.B Yeast respires and produces carbon dioxide, which forms bubbles in the dough.C Yeast produces oxygen, which forms bubbles in the dough.D Heat turns water in the flour into steam. [1]

1. (a) Which enzyme is added to crushed fruit to increase the volume of juice extracted?A amylaseB lipaseC pectinaseD protease [1]

1. (a) State three reasons why bacteria are useful in biotechnology and genetic modification. [3]

1. (a) Explain why bread dough containing yeast is left in a warm place before baking. [2]
2. (b) State what happens to the yeast and the ethanol when the bread is baked. [2]

A student boiled some glucose solution, let it cool to 35 °C, then added yeast. A layer of vegetable oil was poured on top. A delivery tube led from the flask into a test tube of limewater.

1. (a) Explain why the glucose solution was boiled and then cooled before the yeast was added. [2]
2. (b) Explain why a layer of oil was poured onto the surface of the mixture. [1]
3. (c) State what the limewater shows and the change you would see. [2]
4. (d) Suggest how the student could measure the rate of respiration. [1]

1. (a) Name the type of microorganism used to produce penicillin. [1]
2. (b) State one other product made on a large scale in fermenters. [1]
3. (c) State why penicillin is useful in medicine. [1]

1. (a) Lactose-free milk is made by treating milk with an enzyme. Which row is correct?A enzyme lactase; products glucose and galactoseB enzyme lactase; products glucose and fructoseC enzyme amylase; products glucose and galactoseD enzyme maltase; products glucose only [1]

1. (a) An industrial fermenter has a jacket of cold water flowing around it. What is the main reason for this?A to supply water as a raw material for the microorganismsB to remove heat released by the respiring microorganisms and keep the optimum temperatureC to heat the contents so the microorganisms grow fasterD to keep the contents sterile [1]

In a sugar mill in Sindh, molasses from sugar cane is mixed with water and yeast in large tanks to make ethanol for use as a biofuel.

1. (a) Write the word equation for the anaerobic respiration of glucose by yeast. [2]
2. (b) Explain why air is kept out of the fermenter. [2]
3. (c) Suggest one advantage of using ethanol made from sugar cane as a fuel instead of petrol. [1]

1. (a) Name the enzymes in a biological washing powder that remove: (i) a blood or egg stain; (ii) a cooking oil stain. [2]
2. (b) Explain why biological washing powders work well at 30–40 °C. [2]
3. (c) Explain why a biological washing powder is less effective in a 90 °C wash. [2]

A dairy in Lahore treats milk with lactase. Before treatment the milk contains 4.8 g of lactose per 100 cm³. After treatment it contains 0.3 g of lactose per 100 cm³.

1. (a) Calculate the percentage of the lactose that was broken down. Give your answer to 3 significant figures. [2]
2. (b) Explain why some people need to drink lactose-free milk. [2]
3. (c) Suggest why lactose-free milk tastes sweeter than ordinary milk. [1]

1. (a) State four conditions that are monitored and controlled inside a fermenter used to produce penicillin, and give a reason for controlling each. [4]
2. (b) Explain why the fermenter and nutrient medium are sterilised with steam before use. [2]

A student mixed 50 g of apple pulp with 2 cm³ of pectinase at different temperatures, then filtered for 20 minutes and measured the volume of juice. A control used boiled pectinase at 40 °C.Temperature / °C: 20, 30, 40, 50, 60Volume of juice / cm³: 8, 14, 21, 17, 6Control (boiled enzyme): 5 cm³

1. (a) State the optimum temperature for pectinase in this experiment. [1]
2. (b) Explain why a beaker of pulp with boiled pectinase was set up. [2]
3. (c) Calculate the percentage increase in juice volume at 40 °C compared with the control. Give your answer to the nearest whole number. [2]
4. (d) Explain why less juice was collected at 60 °C. [2]
5. (e) Suggest how the student could find the optimum temperature more precisely. [1]

The table shows changes in a penicillin fermenter.Time / hours: 0, 20, 40, 60, 80, 100, 120Fungal biomass / g per dm³: 1, 6, 14, 20, 21, 21, 20Penicillin / units per cm³: 0, 0, 2, 10, 22, 31, 35

1. (a) Describe the changes in biomass of the fungus over the 120 hours. [2]
2. (b) Calculate the mean rate of penicillin production, in units per cm³ per hour, between 60 and 100 hours. [2]
3. (c) Suggest why most of the penicillin is produced after 60 hours. [2]
4. (d) Suggest why the fermentation is stopped at about 120 hours. [1]

A fermenter is started with 50 bacteria. In ideal conditions this species of bacterium divides once every 20 minutes.

1. (a) Calculate how many bacteria would be present after 4 hours, assuming every cell divides every 20 minutes. [2]
2. (b) Explain why the number of bacteria in a real fermenter does not keep increasing at this rate. [3]

A student mixed 50 g of flour, 2 g of dried yeast and different masses of sugar with 30 cm³ of warm water. Each dough was pushed to the bottom of a measuring cylinder and the increase in volume was measured after 30 minutes.Mass of sugar / g: 0, 2, 4, 6, 8Increase in volume / cm³: 4, 12, 20, 24, 25

1. (a) Describe the effect of sugar mass on the increase in dough volume. [2]
2. (b) Calculate the mean rate of increase in volume, in cm³ per minute, for the dough with 4 g of sugar. Give your answer to 2 significant figures. [2]
3. (c) Explain why the dough with no sugar still increased in volume a little. [1]
4. (d) Suggest why increasing the sugar from 6 g to 8 g had little effect. [1]
5. (e) Describe how the student could keep the temperature the same for all the cylinders. [1]
6. (f) Suggest one improvement to make the results more reliable. [1]

A company grows genetically modified bacteria in a 10 000 dm³ fermenter. At the end of a batch the broth contains 1.2 g of insulin per dm³. Only 70% of this insulin is recovered when it is purified.

1. (a) Calculate the mass of purified insulin, in kg, obtained from one batch. [2]
2. (b) Explain why the contents of the fermenter are stirred continuously. [3]
3. (c) Suggest why probes for pH and temperature are connected to a computer. [1]

1. (a) What is meant by genetic modification?A changing the genetic material of an organism by removing, changing or inserting individual genesB choosing parents with useful features and breeding them over many generationsC producing genetically identical offspring by asexual reproductionD a random change in the base sequence of DNA [1]

1. (a) Give three examples of genetic modification. [3]

1. (a) State what is meant by a plasmid. [1]
2. (b) State what is meant by a recombinant plasmid. [1]
3. (c) Name the type of enzyme used to cut open a plasmid. [1]

The steps below describe how bacteria are modified to make a human protein, but they are in the wrong order.P – The human gene is cut out using a restriction enzyme.Q – The modified bacteria multiply in a fermenter.R – The gene is joined into the plasmid using DNA ligase.S – A plasmid is cut open with the same restriction enzyme.T – The protein is extracted and purified.U – The recombinant plasmid is put into a bacterium.

1. (a) Put steps P to U in the correct order, starting with P. [3]

1. (a) In genetic modification, which enzyme joins a human gene into a bacterial plasmid?A restriction enzymeB DNA ligaseC amylaseD protease [1]

1. (a) Outline how bacteria can be genetically modified to produce human insulin. [6]

1. (a) Explain why the same restriction enzyme must be used to cut both the human DNA and the plasmid. [2]
2. (b) State what is meant by a sticky end. [1]

1. (a) Explain how growing herbicide-resistant soya benefits a farmer. [2]
2. (b) Suggest one risk of growing herbicide-resistant crops. [1]

1. (a) A student says: 'GM bacteria make human insulin because they have human DNA inside them.' Explain what else must happen for the bacterium to make insulin. [2]
2. (b) Suggest why bacteria, rather than human cells, are used to produce insulin on a large scale. [2]

Cotton plants have been genetically modified to make a protein that is toxic to caterpillars which feed on them. Data from one cotton-growing district:Before GM cotton: 12 insecticide sprays per season; yield 1.9 tonnes per haAfter GM cotton: 5 insecticide sprays per season; yield 2.4 tonnes per ha

1. (a) Calculate the percentage decrease in the number of sprays and the percentage increase in yield. Give your answers to 3 significant figures. [2]
2. (b) Discuss the advantages and disadvantages of growing insect-resistant genetically modified crops. [6]

1. (a) Explain why rice has been genetically modified to contain β-carotene. [2]
2. (b) Suggest two concerns some people have about growing this rice. [2]
3. (c) Suggest one alternative way of reducing vitamin A deficiency. [1]

1. (a) Before GM bacteria were used, insulin for people with diabetes was extracted from the pancreases of cattle and pigs. Explain the advantages of insulin produced by GM bacteria. [4]
2. (b) Explain why a human gene can produce human insulin inside a bacterium. [2]

A trial compared genetically modified insect-resistant maize with non-GM maize.Plants damaged by stem borer: GM field 3%; non-GM field 28%

1. (a) Calculate the percentage reduction in plants damaged by the stem borer in the GM field compared with the non-GM field. Give your answer to 3 significant figures. [2]
2. (b) Suggest why 3% of the GM plants were still damaged. [1]
3. (c) Farmers are told to plant a strip of non-GM maize beside their GM maize. Explain how this slows down the evolution of resistance in the stem borer. [3]