CAIE IGCSE Biology 18.3.5 Evolution of Antibiotic-Resistant Bacteria
Practise explaining antibiotic resistance through mutation, selection, survival, reproduction and inheritance in bacterial populations.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Exam points
- sequence random mutation, antibiotic exposure and survival of resistant bacteria
- explain how survivors reproduce and pass resistance alleles to their offspring
- interpret resistance graphs or inhibition zones without describing antibiotic adaptation
18.3.5—Development of strains of antibiotic question 1
A scientist tested the resistance of one strain of bacteria to different antibiotics.
The scientist tested solutions of five different antibiotics, A to E.
She soaked a paper disc in each antibiotic solution.
The paper discs with antibiotics were placed in a Petri dish containing bacteria on agar jelly.
Fig. 4.2 is a diagram of the appearance of the Petri dish after 48 hours. The shaded areas show where bacteria grew. The clear areas show where bacteria did not grow.
Fig. 4.2
The results in Fig. 4.2 show that this strain of bacteria is resistant to antibiotic A.
Five years ago, a similar investigation found that the clear area for antibiotic A was the same size as antibiotic B is in Fig. 4.2.
Explain how bacteria become resistant to antibiotics.
All question bank results loaded