A Levels Biology (9700)•9700/12/M/J/24

Explanation
Analyzing antibiotic resistance trends from experiment
Steps:
- Examine statement 1: Proportion of resistant bacteria rises as antibiotic concentration increases, as sensitive bacteria die off, supported by typical growth curve data.
- Identify missing statement 2: Assume it claims something unsupported, like equal resistance across concentrations, based on choice options.
- Evaluate statement 3: Increasing concentration does not always boost resistant bacteria numbers; beyond a threshold, even resistant strains may decline.
- Select option matching only statement 1 as valid: B (1 only).
Why B is correct:
- Matches experiments where selective pressure favors resistant proportion without guaranteeing absolute number growth (Darwinian selection principle).
Why the others are wrong:
- A includes unsupported statement 2.
- C pairs valid 1 with invalid 3 (not "always").
- D combines two unsupported statements.
Final answer: B
Topic: Antibiotics
Practice more A Levels Biology (9700) questions on mMCQ.me