Some bacteria are pathogens. The bacteria were cultured in a Petri dish on nutrient agar jelly. The bacteria spread across the entire surface of the agar jelly. Three paper discs were then set on the agar jelly. Each paper disc held a different antibiotic. The bacteria were allowed to grow for 24 hours at 35^{\circ}C.
(a(i))[1]
Suggest why clear regions appear around some of the paper discs after 24 hours.
(a(ii))[2]
Put the antibiotics in order from the one that is most effective to the one that is least effective. Give a reason for your answer.
(b)[3]
State three similarities between a plant cell and the bacterial cell shown in Fig. 3.2.
(c)[2]
Identify the examples of direct contact by putting a tick (✓) in the correct boxes in Table 3.1.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “killed the bacteria / prevented the growth of bacteria” …