1. 1
   A microbiologist explains to trainee biotechnologists why bacteria, rather than larger organisms such as mammals, are usually chosen for large-scale industrial biotechnology processes such as manufacturing enzymes.

   (a)

   Which characteristic of bacteria makes them especially useful for large-scale industrial biotechnology?

   [1 mark]

   • AThey reproduce very rapidly, so large numbers of cells can be grown in a short time
   • BThey have a very slow rate of reproduction, giving stable colonies
   • CThey contain chloroplasts, allowing them to photosynthesise their own food
   • DThey are multicellular organisms with specialised tissues

   (b)

   Bacteria naturally contain small circular pieces of DNA, separate from the main chromosome. What are these called, and why are they useful in biotechnology?

   [1 mark]

   • ARibosomes; they build proteins directly from amino acids
   • BPlasmids; they can be used as vectors to carry genes into bacteria
   • CMitochondria; they release energy through aerobic respiration
   • DNuclei; they store the bacterium's entire genome

   (c)

   Besides their plasmids, give two other reasons why bacteria are particularly suitable organisms for use in biotechnology and genetic modification.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An apple juice company crushes apples into a pulp and adds the enzyme pectinase to the pulp before pressing out the juice, in order to increase the amount and clarity of juice obtained.

   (a)

   What does pectinase break down within the crushed apple pulp?

   [1 mark]

   • AStarch stored inside the apple cells
   • BProtein found in the apple's seeds
   • CPectin, a substance found in plant cell walls
   • DCellulose fibres found only in animal tissue

   (b)

   What effect does breaking down pectin in the crushed apple pulp have on the juice produced?

   [1 mark]

   • AIt turns the juice cloudy and reduces the amount produced
   • BIt converts the juice's sugar into alcohol
   • CIt has no effect on the juice, only on the solid pulp remaining
   • DIt increases the amount of juice released and makes the juice clearer

   (c)

   Explain, in terms of the structure of plant cells, why breaking down pectin with pectinase increases the amount of juice that can be extracted from the crushed apple pulp.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A biotechnology company produces two enzyme-based consumer products: a biological washing powder containing protease and lipase for washing clothes at low temperatures, and a lactase treatment used by dairies to produce lactose-free milk for people who are lactose intolerant.

   (a)

   Explain how the protease and lipase in the biological washing powder are able to remove food stains from clothes, and explain one advantage of being able to use this washing powder at a lower temperature than a non-biological powder.

   [3 marks]

   (b)

   Describe how lactase is used to produce lactose-free milk, and explain why this product is useful to people who are lactose intolerant.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A biotechnology company runs two very different production processes at its site: in one, bacteria have been genetically modified to produce human growth hormone, used to treat children with a growth hormone deficiency; in the other, the mould Penicillium (which has not been genetically modified) is grown in a large fermenter to produce the antibiotic penicillin, and the resulting mycelium can also be processed into mycoprotein for use as a meat substitute.

   (a)

   Explain fully, in the correct order, the entire process used to genetically modify bacteria so that they produce human growth hormone, from isolating the human gene through to the bacteria expressing it, naming the enzymes involved at each stage.

   [6 marks]

   (b)

   Explain how growing the genetically modified, growth-hormone-producing bacteria differs from growing the non-genetically-modified Penicillium mould to produce penicillin and mycoprotein, and explain one similarity between the two fermenter processes.

   [6 marks]

   Total for question 4: 12 marks

5. 5
   An energy company grows large tanks of yeast in the absence of oxygen, feeding the yeast a sugar solution, in order to produce ethanol that will be blended into biofuel for use in vehicles.

   (a)

   Which type of respiration occurs in the yeast under these oxygen-free conditions?

   [1 mark]

   • AAerobic respiration
   • BAnaerobic respiration
   • CPhotosynthesis
   • DOsmosis

   (b)

   What are the two main products of anaerobic respiration in yeast?

   [1 mark]

   • AEthanol and carbon dioxide
   • BLactic acid and oxygen
   • CGlucose and water
   • DOxygen and carbon dioxide

   (c)

   Write a word equation for anaerobic respiration in yeast, and explain why the yeast tanks must be kept free of oxygen for ethanol to be produced.

   [2 marks]

   Total for question 5: 4 marks

6. 6
   A pharmaceutical company grows the mould Penicillium in a large industrial fermenter under carefully controlled aerobic conditions, in order to produce the antibiotic penicillin on a large scale.

   (a)

   Which gas must be continuously supplied to the fermenter for the Penicillium to grow and produce penicillin efficiently?

   [1 mark]

   • ANitrogen
   • BCarbon dioxide
   • CHydrogen
   • DOxygen

   (b)

   Why must the temperature inside the fermenter be carefully controlled during penicillin production?

   [1 mark]

   • ATemperature has no effect on Penicillium growth or penicillin production
   • BTemperature only needs to be controlled during the first hour of fermentation
   • CIf it is too high, enzymes in the Penicillium may be denatured; if too low, growth and penicillin production slow down
   • DA higher temperature always increases penicillin production, with no upper limit

   (c)

   Besides temperature and oxygen supply, state two other conditions that must be controlled inside the fermenter for efficient penicillin production, and explain why each must be controlled.

   [2 marks]

   Total for question 6: 4 marks

7. 7
   A food technology company operates a large industrial fermenter in which a fungus is grown under aerobic conditions to produce mycoprotein, a protein-rich meat substitute that is harvested from the fungal biomass produced.

   (a)

   Describe how mycoprotein is produced in the fermenter, and explain why oxygen must be supplied throughout the process.

   [3 marks]

   (b)

   Explain why the temperature, pH, nutrient supply and removal of waste products must all be carefully controlled inside the fermenter throughout mycoprotein production.

   [4 marks]

   Total for question 7: 7 marks

8. 8
   A biotechnology company runs two separate large-scale processes: in one, bacteria have been genetically modified to produce human blood clotting factor VIII, used to treat people with haemophilia; in the other, ordinary (non-genetically-modified) yeast is grown anaerobically in large tanks to produce ethanol for use as a biofuel.

   (a)

   Explain fully, in the correct order, the entire process used to genetically modify bacteria so that they produce human clotting factor VIII, from isolating the human gene through to the bacteria expressing it, naming the enzymes involved at each stage.

   [6 marks]

   (b)

   Explain how growing the genetically modified, clotting-factor-producing bacteria differs from growing the non-genetically-modified yeast to produce ethanol, and explain one similarity between the two processes.

   [6 marks]

   Total for question 8: 12 marks

End of questions