Question

part a
over time, bacteria have become increasingly resistant to antibiotics. which of the following best explains this in terms of natural selection?
some bacteria began to tolerate the antibiotics, and passed this ability to their offspring.
antibiotics caused bacteria to reproduce more quickly than normal.
bacteria that happen to have natural resistance to antibiotics survived and reproduced.
antibiotics caused mutations in the bacteria that were exposed to the largest doses of antibiotics.
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part b
which of the following correctly describes what the video referred to as a \microbial cure\?
antibiotics are used to treat all infections, whether they are bacterial or viral, in order to bring about a full cure.
antibiotics are used every time a patient has disease symptoms, in order to prevent an infection from occurring.
antibiotics are used only until the patient feels better, therefore reducing the exposure to the antibiotics.
antibiotics are used to kill all of the infectious bacteria in a person.
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Explanation:

Part A:

Natural selection explains that organisms with traits suited to their environment survive and reproduce. For antibiotic resistance, some bacteria naturally have resistance traits; when antibiotics are used, these resistant bacteria survive, reproduce, and pass the resistance to their offspring, leading to increasing resistance over time. The other options are incorrect: antibiotics do not cause faster reproduction, do not induce mutations for resistance, and resistance is a pre-existing trait, not caused by antibiotics.

Part B:

A "microbial cure" means eliminating all infectious bacteria. Antibiotics must kill all infectious bacteria to achieve this; they do not treat viral infections, should be taken for the full course (not just until symptoms end), and are not used every time to prevent infection.

Answer:

Part A: B. Bacteria that happen to have natural resistance to antibiotics survived and reproduced.
Part B: Antibiotics are used to kill all of the infectious bacteria in a person.