Some bacteria are able to grow in streptomycin containing medium due to

Explanation

a)Natural Selection (Correct Answer): Bacteria can develop resistance to antibiotics through natural selection. In a population of bacteria, there can be variations in the presence of certain genetic mutations. When exposed to an antibiotic like streptomycin, the bacteria without the mutations are susceptible and die, while those with mutations that confer resistance survive. Over time, the resistant bacteria reproduce, passing on their resistance genes to the next generation. This process represents natural selection favoring antibiotic-resistant bacteria. b)Induced Mutation:Induced mutations occur when external factors, such as exposure to mutagenic agents (chemicals, radiation, etc.), lead to changes in the DNA of an organism. While mutations can create genetic diversity, allowing for the potential development of antibiotic resistance, the specific resistance to streptomycin in bacteria primarily results from natural selection. c)Reproductive Isolation:Reproductive isolation refers to mechanisms that prevent different species from interbreeding. It is not directly related to the development of antibiotic resistance in bacteria. Antibiotic resistance is primarily a genetic adaptation within a single bacterial species. d)Genetic Drift:Genetic drift is a mechanism that can cause changes in the frequency of particular genetic variants in a small population due to chance events. While it can lead to genetic changes over time, the development of antibiotic resistance is more directly related to natural selection in response to antibiotic exposure. In summary, natural selection is the most relevant and widely observed mechanism by which bacteria can develop antibiotic resistance when exposed to antibiotics like streptomycin. Other mechanisms, such as induced mutation, reproductive isolation, and genetic drift, may play roles in evolutionary processes but are less directly related to antibiotic resistance.