0610_w11_qp_31
A paper of Biology, 0610
Questions:
6
Year:
2011
Paper:
3
Variant:
1

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For Examiner's Use Penicillin is an antibiotic produced by the fungus Penicillium chrysogenum. shows the process used to produce penicillin. pH monitor temperature monitor acid or alkali fungus and nutrients filtrate containing penicillin residue waste gases sterile air cooling water in cooling water out stirring paddles water jacket fermenter filter For Examiner's Use Enzymes in the fungus are used to make penicillin. Explain why there is a water jacket around the fermenter and why acids or alkalis are added to the fermenter. water jacket addition of acids or alkalis For Examiner's Use shows the mass of fungus and the yield of penicillin during the fermentation process. time / hours 100 120 140 160 mass of fungus / g dm–3 yield of penicillin / arbitrary units nutrients added penicillin penicillin fungus fungus penicillin fungus State the time interval over which the fungus grew at the maximum rate. As the fungus grows in the fermenter, the nuclei in the fungal hyphae divide. State the type of nuclear division that occurs during the growth of the fungus in the fermenter. For Examiner's Use Explain why the growth of the fungus slows down and stops. Penicillin is not needed for the growth of P. chrysogenum. State the evidence from that shows that penicillin is not needed for this growth. The people in charge of the penicillin production emptied the fermenter at 160 hours. Use the information in to suggest why they did not allow the fermentation to continue for longer. For Examiner's Use Downstream processing refers to all the processes that occur to the contents of the fermenter after it is emptied. This involves making penicillin into a form that can be used as a medicine. Explain why downstream processing is necessary. Explain why antibiotics, such as penicillin, kill bacteria but not viruses.
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For Examiner's Use The brown plant hopper is a serious insect pest of rice. Spraying with pesticides is a common way to control it. However, brown plant hoppers have become resistant to pesticides. shows the effect of spraying pesticides against populations of this insect pest. days after transplanting rice mean number of brown plant hoppers per m2 sprays with pesticide Define the term population. For Examiner's Use Use to describe the effect of pesticides on populations of the brown plant hopper. Some pesticides used against insects kill them on contact. Others are systemic pesticides. Explain how these systemic pesticides kill insects. For Examiner's Use As an alternative to spraying pesticides, some farmers use predatory animals, such as the hunting spider, Lycosa pseudoannulata, to control brown plant hoppers. During an investigation into the effectiveness of this method, brown plant hoppers were put into cages in rice fields. The plant hoppers could not leave the cages but were able to feed. Predators, such as hunting spiders, could enter some of the cages to feed. shows the change in numbers of brown plant hoppers in these cages over a period of time. mean number of brown plant hoppers per cage time / days cages closed cages closed to predators to predators cages open cages open to predators to predators cages closed to predators cages open to predators For Examiner's Use Use the information in to explain the advantages of using predators, such as spiders, to control brown plant hoppers. Rice growing has involved the destruction of forests. Describe the long-term effects of deforestation on the environment.