Drugs Banker

1. (a) For which disease would a doctor prescribe an antibiotic?A influenzaB measlesC choleraD the common cold [1]

1. (a) State what an antibiotic is used for. [1]
2. (b) A student with a bad cold asks a doctor for antibiotics. Explain why the doctor refuses. [2]

1. (a) State one disease, caused by bacteria, that can be treated with antibiotics. [1]
2. (b) State why some bacterial infections are now difficult to treat with antibiotics. [1]
3. (c) Name one example of a strain of bacteria that is resistant to several antibiotics. [1]

1. (a) Antibiotics affect bacteria but do not affect viruses. Name one structure found in bacteria that is not found in viruses. [1]
2. (b) State whether each disease can be treated with antibiotics: (i) tuberculosis; (ii) HIV/AIDS; (iii) cholera; (iv) influenza. [2]

1. (a) State whether each statement about antibiotics is true or false: (i) Antibiotics kill bacteria. (ii) Antibiotics are effective against all pathogens. (iii) Antibiotics should be taken until the course is finished. (iv) Antibiotics can be used to treat the common cold. [2]
2. (b) Antibodies and antibiotics are often confused. State one difference between them. [1]

1. (a) Explain why a person should not take antibiotics left over from a previous illness, or share them with a family member. [3]
2. (b) State why antibiotics are sometimes called 'a precious resource'. [1]

1. (a) The first antibiotic, penicillin, was obtained from a mould. State the kingdom to which moulds belong. [1]
2. (b) State what happens to bacteria when they are exposed to an antibiotic to which they are not resistant. [1]
3. (c) Suggest why a doctor may change to a different antibiotic if a patient's infection does not improve. [1]

Equal volumes of a culture of a harmless bacterium were spread on agar plates with and without an antibiotic and incubated at 25 °C. Number of colonies: without antibiotic – mean 180; with antibiotic – 17, 20, 17.

1. (a) Calculate the mean number of colonies on plates with antibiotic. [1]
2. (b) Calculate the percentage of colonies that survived on antibiotic plates compared with plates without antibiotic. [2]
3. (c) State what the colonies growing on the antibiotic plates show about those bacteria. [1]

1. (a) Why do antibiotics not cure diseases caused by viruses?A Viruses are too small to be seen by the immune system.B Viruses lack the structures and processes, such as cell walls, that antibiotics act on.C Viruses are always resistant to antibiotics because of mutations.D Antibiotics only work in the gut, and viruses live in the lungs. [1]

1. (a) What is MRSA?A a virus that causes pneumoniaB a strain of bacteria resistant to several commonly used antibioticsC an antibiotic used in hospitalsD a fungus that produces penicillin [1]

1. (a) Explain how the development of resistant bacteria, such as MRSA, can be minimised. [4]
2. (b) Explain why patients are told to finish the full course of antibiotics even when they feel better. [2]

The number of antibiotic prescriptions per 1000 people per day in one district was 5.2 in 2021 and 3.9 in 2024, after a campaign to reduce unnecessary use.

1. (a) Calculate the percentage decrease in antibiotic prescriptions between 2021 and 2024. [2]
2. (b) Suggest two reasons why health authorities wanted to reduce the number of prescriptions. [2]
3. (c) Over the same period, the percentage of infections caused by resistant bacteria in the district did not fall. Suggest one reason. [1]

A student placed discs soaked in antibiotics A and B on agar plates spread with a harmless bacterium and incubated them at 25 °C for 2 days. Diameter of clear zone / mm:A: 26, 24, 25B: 14, 15, 31, 13

1. (a) Calculate the mean diameter of the clear zone for antibiotic A. [1]
2. (b) Identify the anomalous result for antibiotic B and calculate the mean without it. [2]
3. (c) State which antibiotic would be most effective against this bacterium. Explain your answer. [2]
4. (d) Suggest why the plates were incubated at 25 °C rather than 37 °C. [1]

A student prepared an agar plate to test the effect of penicillin on a harmless bacterium.

1. (a) Explain why the student flamed the inoculating loop until it glowed red before use. [1]
2. (b) Explain why the lid was held with two pieces of tape but not sealed all the way round. [2]
3. (c) State why the plate was stored upside down during incubation. [1]
4. (d) After incubation a clear zone appeared around a disc containing penicillin. Explain what this shows. [1]

A survey in a city found that many people bought antibiotics for coughs and fevers without seeing a doctor.

1. (a) In some places antibiotics can be bought from a pharmacy without a doctor's prescription. Explain two ways this can increase antibiotic resistance. [4]
2. (b) Suggest one advantage of a doctor testing a sample of bacteria from the patient before choosing an antibiotic. [1]

A doctor in Peshawar prescribed amoxicillin capsules of 500 mg, one capsule three times a day for 7 days.

1. (a) Calculate the total mass of antibiotic taken during the full course and the number of capsules needed. [2]
2. (b) After 3 days the patient feels better and stops taking the capsules. Calculate the number of capsules not taken. [1]
3. (c) Explain the risk of stopping the course early. [2]

The number of bacteria in samples from a patient with a throat infection (arbitrary units): day 0 – 48; day 3 – 12; day 5 – 25; day 7 – 40.

1. (a) Calculate the percentage decrease in bacteria between day 0 and day 3. [2]
2. (b) The patient stopped taking the antibiotic on day 3. Describe and explain the change in the number of bacteria from day 3 to day 7. [3]

1. (a) Tuberculosis (TB) is treated with antibiotics for at least six months. Suggest why the treatment takes so long. [1]
2. (b) Patients with TB are usually given three or four different antibiotics at the same time. Explain how this reduces the chance of resistant TB bacteria developing. [2]

1. (a) Which action is most likely to reduce the development of antibiotic-resistant bacteria in a community?A taking antibiotics at the first sign of any sore throatB stopping a course of antibiotics as soon as symptoms disappearC using antibiotics only when essential and finishing the full courseD giving leftover antibiotics to family members with similar symptoms [1]

1. (a) Paper discs soaked in four antibiotics, P, Q, R and S, were placed on agar spread with one type of bacterium. After incubation the diameters of the clear zones were P 6 mm, Q 21 mm, R 0 mm, S 14 mm (all discs 6 mm wide). Which conclusion is correct?A P is the most effective antibiotic.B The bacteria are resistant to R, and Q is the most effective.C S is more effective than Q.D All four antibiotics killed the bacteria. [1]

In one country, 202 tonnes of antibiotics were used in a year: 71 tonnes in human medicine and 131 tonnes in farm animals.

1. (a) Calculate the percentage of the total antibiotics used that were given to farm animals. Give your answer to 2 significant figures. [2]
2. (b) Suggest why giving antibiotics routinely to healthy farm animals can affect human health. [3]

Clear zones around two antibiotic discs on a bacterial lawn had diameters of 2.2 cm (antibiotic X) and 1.1 cm (antibiotic Y).

1. (a) Calculate the area of each clear zone. Use area = πr² and give your answers to 2 significant figures. [2]
2. (b) Calculate how many times larger the clear zone area is for X than for Y. [1]
3. (c) Explain why it is better to compare areas rather than diameters. [1]

1. (a) Plan an investigation to find out how the concentration of an antibiotic affects the growth of a harmless bacterium on agar plates. [6]

1. (a) Explain how the use of an antibiotic leads to an increase in the proportion of resistant bacteria in a population. [4]
2. (b) A student writes 'the antibiotic makes the bacteria become immune'. Explain why this statement is wrong. [2]

1. (a) Calculate the time taken for one resistant bacterium to produce over 4000 bacteria if it divides every 20 minutes. Show your working. [2]
2. (b) Use your answer to explain why resistance can spread through a bacterial population very quickly when an antibiotic is used. [2]

A hospital introduced compulsory hand cleaning with alcohol gel and stricter rules on prescribing antibiotics. MRSA infections per 10 000 patients: 2020 – 6.8; 2024 – 1.7.

1. (a) Calculate the percentage decrease in MRSA infections between 2020 and 2024. [2]
2. (b) Explain how each of the two measures could have contributed to the decrease. [4]

Data for four countries – antibiotic doses per 1000 people per day and % of E. coli infections resistant to one antibiotic: Q – 10, 9 %; R – 18, 20 %; S – 25, 29 %; T – 32, 41 %.

1. (a) Describe the relationship shown in the data. [2]
2. (b) A student concludes that 'antibiotic use is the only cause of resistance'. Evaluate this conclusion. [3]

1. (a) Which is the best definition of a drug?A any substance that kills bacteriaB any substance taken into the body that modifies or affects chemical reactions in the bodyC any substance made by a doctorD any substance that is addictive [1]

1. (a) Explain why both a painkiller such as paracetamol and an antibiotic such as amoxicillin are drugs. [2]
2. (b) State the difference in what these two drugs are used for. [2]

1. (a) A herbal tea is advertised as a cure for influenza. Using the definition of a drug, explain what would need to be true for the tea to be classed as a drug. [2]
2. (b) Explain why it would not be useful for a patient with influenza to take an antibiotic instead. [2]
3. (c) Suggest how scientists could test fairly whether the tea reduces the length of the illness. [2]