Antibiotics — final check

1. explain / describe

A patient with a bacterial infection of the lungs is given an antibiotic. (a) Explain why the antibiotic is a drug. (b) Describe how the antibiotic helps the patient to get better.

(a) Why it is a drug

(b) How it helps

2. identify

Three antibiotics R, S and T are tested on three plates of the same bacterium, with a water disc on each plate. The mean zone diameters are R 24 mm, S 9 mm, T 17 mm and water 6 mm. Which conclusion do these results support?

Circle one answer.

• R is the best of the three antibiotics for treating any infection.
• The bacteria on the plates are resistant to the water disc.
• R gave the widest zone of no visible growth under these conditions.
• S had no effect at all on the growth of these bacteria.

3. identify

Which statements are correct?

Tick every correct statement.

• Resistance means that the patient's body no longer responds to the antibiotic.
• An antibiotic shortens a bout of flu if it is taken early enough.
• Antibiotics kill bacteria but do not affect viruses.
• Bacteria resistant to an antibiotic make it less effective against the infections they cause.

4. explain

Supplement. MRSA is a strain of the bacterium Staphylococcus aureus that is resistant to several common antibiotics. (a) Explain how a strain like MRSA becomes common where antibiotics are used a lot. (b) Explain how using antibiotics only when essential can limit the development of strains like MRSA.

(a) How it becomes common

(b) Using antibiotics only when essential