Question

penicillin was considered a \miracle drug\ for all of the following reasons except
it does not affect eukaryotic cells
in inhibits gram - positive cell wall synthesis
it was the first antibiotic
it has selective toxicity
question 12 (1 point)
which of the following terms refers to the ability of an antimicrobial drug to harm
the target microbe without harming the host?
selective toxicity
spectrum of activity
therapeutic level
mode of action

Explanation:

• For the first question: Penicillin is a beta - lactam antibiotic. It inhibits the synthesis of the peptidoglycan layer in the cell wall of gram - positive bacteria. Since human cells (eukaryotic) do not have a peptidoglycan cell wall, it does not affect eukaryotic cells. Selective toxicity means that the drug harms the microbe but not the host. However, the fact that it was the first antibiotic is not the reason it is called a "miracle drug". The key properties that make it a "miracle drug" are related to its mechanism of action (inhibiting cell - wall synthesis in bacteria, not affecting eukaryotes) and its selective toxicity.
• For the second question: Selective toxicity is defined as the ability of an antimicrobial drug to harm the target microbe without harming the host. The spectrum of activity refers to the range of microbes (e.g., gram - positive, gram - negative, etc.) that a drug can act against. Therapeutic level is the concentration of the drug in the body that is effective for treatment. Mode of action is how the drug acts on the microbe (e.g., inhibiting protein synthesis, cell - wall synthesis, etc.).

Answer:

• First question: it was the first antibiotic
• Second question: selective toxicity