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Difficulty: HardEvolution and Adaptation

When a bacterial population is exposed to penicillin, individual bacterial cells actively alter their genetic code in direct response to the antibiotic to develop and acquire resistance during their lifespan.

Answer: Answer

Answer

False. Individual bacteria do not purposefully mutate or alter their genetic code in response to antibiotics; resistance results from natural selection acting on pre-existing random mutations within the population.
The statement is false because natural selection relies on pre-existing random genetic variations within a population. Environmental pressures such as antibiotics do not cause directed genetic changes in individual cells; instead, they selectively eliminate non-resistant organisms, leaving resistant variants to reproduce.

Step-by-Step Solution

1
Identify the biological level at which evolutionary adaptation takes place.
Evolution and adaptation occur at the population level across multiple generations, whereas individual organisms retain their inherited genetic profile throughout their lifespan.
Acquired non-heritable physiological changes during an individual's lifetime do not alter the underlying genetic code through directed mutation.
2
Analyze the origin and nature of genetic mutations in natural selection.
Mutations occur spontaneously and randomly due to errors in DNA replication or environmental mutagens, prior to and independent of selective pressure.
An environmental stressor like an antibiotic does not direct or instruct specific genetic changes to solve a physiological challenge.
3
Evaluate the mechanism of antibiotic resistance development.
Penicillin acts as a selective agent that destroys susceptible bacterial cells, allowing the rare individuals with pre-existing resistance mutations to survive and reproduce differentially.
This differential survival and reproduction shifts the allele frequency of the entire population over time, which demonstrates Darwinian natural selection.

Key Concept

Natural Selection vs. Acquired Characteristics in Bacterial Resistance
Estimated Time:1m 0s
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Topics

Evolution and Adaptation

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