Question

Certain bacterial strains have traits that allow them to resist the effects of antibiotic drugs. How do the resistance traits arise in a bacterial population, and under what circumstances will the resistance traits be most common?

a. Resistance traits are produced because antibiotic drugs cause mutations in bacterial cells. The resistance traits only occur in the presence of antibiotics.
b. The resistance traits are developed by bacteria when they detect the drugs in their environment, through mutations that counteract the drugs' effects. Thus, they are most common wherever the drugs are present.
c. The resistance traits arise as the immune systems of the bacteria detect and respond to the drugs. Therefore, individual bacteria become more and more resistant if they are exposed to antibiotic drugs.
d. The resistance traits are produced by chance mutations and are present to varying degrees in most bacterial populations. Resistance traits will be most prevalent, however, in bacteria that are chronically exposed to antibiotic drugs.

Answer 1

Bacterial resistance traits arise from chance mutation option (a) and genetic variety that exists within populations, becoming more prevalent through natural selection when antibiotics are used, killing bacteria without the resistance gene.

Step-by-step explanation:

The resistance traits in bacterial populations most commonly arise through chance mutations and natural selection, not directly due to the presence of antibiotic drugs. Although mutations that provide antibiotic resistance can occur, they are not specifically caused by the application of antibiotics.

Instead, mutations creating resistance traits are part of the existing genetic variety within a bacterial population. When an antibiotic is used, it kills bacteria that do not have the resistance trait, which means only those with the resistance genes survive and reproduce.

Over time, this selective pressure increases the frequency of the resistance traits within the population, especially in environments where antibiotics are used regularly.

Moreover, the overuse and misuse of antibiotics in both healthcare and agriculture contribute to the selection of resistant strains. Not completing a prescribed antibiotic course or using antibiotics inappropriately can leave some bacteria alive, ones that have or acquire resistance genes, which then propagate, passing on their resistance to future generations.

Thus, resistance traits are most prevalent in bacterial populations that are chronically exposed to antibiotic drugs.