A population of bacteria may evolve resistance to a drug over time. This graph shows the
growth of a bacterial population before and after the introduction of an antibiotic, with some
bacteria becoming resistant to the antibiotic. Part B . Thinking critically Which three statements
may correctly explain why the population size increases after time point C? Because the
population grew more rapidly after time point C, the bacteria must have acquired a second drug-
resistance mutation. 0 The population increase just after time point C indicates that antibiotic use
was discontinued Bacteria that acquired a mutation that conferred drug- resistance had a growth
advantage over non-resistant bacteria. Between time points C and D, drug-resistant bacteria were
reproducing faster than non- drug resistant bacteria were dying Time The few drug-resistant
bacteria in the population reproduced, quickly leading to a large drug-resistant population.
Solution
Which three statements may correctly explain why the population size increases after time point
C?
A) Because the population grew more rapidly after time point C, the bacteria must have acquired
a second drug-resistance mutation.
B) The population increase just after time point C indicates that antibiotic use was discontinued.
C) Bacteria that acquired a mutation that conferred drug-resistance had a growth advantage over
non-resistant bacteria.
growth of a bacterial population before and after the introduction of an antibiotic, with some
bacteria becoming resistant to the antibiotic. Part B . Thinking critically Which three statements
may correctly explain why the population size increases after time point C? Because the
population grew more rapidly after time point C, the bacteria must have acquired a second drug-
resistance mutation. 0 The population increase just after time point C indicates that antibiotic use
was discontinued Bacteria that acquired a mutation that conferred drug- resistance had a growth
advantage over non-resistant bacteria. Between time points C and D, drug-resistant bacteria were
reproducing faster than non- drug resistant bacteria were dying Time The few drug-resistant
bacteria in the population reproduced, quickly leading to a large drug-resistant population.
Solution
Which three statements may correctly explain why the population size increases after time point
C?
A) Because the population grew more rapidly after time point C, the bacteria must have acquired
a second drug-resistance mutation.
B) The population increase just after time point C indicates that antibiotic use was discontinued.
C) Bacteria that acquired a mutation that conferred drug-resistance had a growth advantage over
non-resistant bacteria.
