2 marksDefine the term, 'drug'.
1 markIdentify the organ that is the primary site of drug metabolism.
1 markState the name of the group of drugs that are used to treat the symptoms or causes of a disease.
1 markState the name of the class of drugs that is used to treat bacterial infections.
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2 marksFig. 1 shows events in the use of an antibiotic drug.
Fig. 1
Explain what Fig. 1 depicts.
1 markA patient in a doctor's surgery is diagnosed with the influenza virus and asks for antibiotics to be prescribed.
Explain why the doctor would deny this request and suggest other treatments.
2 marksA different patient is prescribed antibiotics for a skin infection.
After a few days, the patient has completed 3/4 of the dose and feels better, having experienced relief from the symptoms of the infection.
He decides to stop taking the antibiotics.
Explain why this is not advisable.
1 markState the name of the small circular loop of DNA that can be passed between bacterial cells and can carry antibiotic resistance genes.
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1 markMicrobiologists test strains of bacteria for antibiotic resistance.
They do this by soaking paper discs in antibiotics and placing them on bacteria growing in Petri dishes.
The paper discs in the centre of Petri dishes E and F in Fig. 1 have been soaked in penicillin.
Fig. 1
State the type of microorganism that produces penicillin.
2 marksState and explain the evidence from Fig. 1 that suggests that the bacteria in dish F are resistant to penicillin.
7 marks[6]
3 marksSome bacteria and viruses cause disease but many are useful to the biotechnology industry.
Explain why bacteria are useful in biotechnology.
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1 markSome scientists investigated the effect of two antibiotics (methicillin and penicillin) on the growth of two different bacteria.
They used filter paper discs soaked in antibiotic solution and placed the discs on two agar plates, one had been spread with bacteria A and the other with bacteria B.
The filter paper discs were prepared as follows:
Fig. 1 shows the results from the investigation:
Suggest what the paper disc might have been soaked in for the control.
4 marksDescribe and explain the results in Fig. 1.
2 marksPredict and explain the appearance of a petri dish that is used to grow a strain of bacteria, Bacteria C, which possesses resistance to methicillin and penicillin.
3 marksDNA analysis of the three strains of bacteria (A, B and C) suggests an evolutionary link between them.
Bacteria C is thought to have evolved from one of the other two strains.
Suggest how bacteria C may have evolved from the other strains.
[1]
Predict and explain whether Bacteria C is more likely to have evolved from Bacteria A or Bacteria B.
[2]
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3 marksTable 1 shows some of the reasons.
Place a tick (✓) in the boxes that are genuine factors why antibiotics can lose their effectiveness in combatting medical and veterinary diseases.
Table 1
| factor | contributes to antibiotics becoming less effective? |
| doctors prescribing antibiotics for viral infections | |
| large scale use of antibiotics as disease prevention | |
| doctors prescribing antibiotics for bacterial infections | |
| bacteria evolving defence mechanisms | |
| antibiotics 'wearing out' through overuse | |
| patients always finishing their course of antibiotics |
1 markMRSA strain is a strain of bacteria often referred to as a 'superbug'. The SA part of the abbreviation 'MRSA' stands for Staphylococcus aureus, a species of bacteria.
Suggest what the 'R' of MRSA stands for.
2 marksExplain why this is generally acceptable in the development of new antibiotics.
2 marksSuggest why antibiotics tend to be effective against bacterial cells but not against animal cells.
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2 marksPrior to passing the dumpsite, the stream passes through a large urban township with limited sanitation.
The levels of antibiotics are found in Table 1.
Table 1
| Antibiotic | Level in stream water after dumpsite / arbitrary units | Level in stream upstream of the dumpsite / arbitrary units |
|
A |
12 | 10 |
| B | 34 | 8 |
| C | 2 | 3 |
Calculate the percentage increase of antibiotic B detected as the stream flows from the township and past the dumpsite.
2 marksSuggest two ways in which antibiotics may have found their way into the water as shown in Table 1.
2 marksSuggest two possible risks of antibiotics entering the environment such as in sewage and wastewater.
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