Final answer:
Chemicals that selectively target and inhibit the proliferation of microorganisms without harming the host are known as antibiotics. Antiseptics, which are safe to use on living tissues to control microbial growth, also exemplify selective toxicity.
Step-by-step explanation:
Understanding Antimicrobial Agents
Chemicals that interfere directly with the proliferation of microorganisms at concentrations tolerated by the host and are selectively toxic are known as antibiotics. Antibiotics are antimicrobial drugs that target specific microbial structures and enzymes, effectively killing or inhibiting the growth of microbes while minimizing harm to the host. On the other hand, antiseptics are antimicrobial chemicals safe for use on living tissues and aim to prevent infection.
For example, if a disinfectant is applied to an area, its purpose is to reduce the number of microorganisms on inanimate surfaces. However, if you're applying an antiseptic, you are using it directly on living skin or tissues to control microbial growth without causing tissue damage. The goal is to achieve selective toxicity, where the chemical agents are potent against microorganisms but safe for the host, whether used in antiseptics or as antibiotics.
In the context of the choices provided, the answer to the question regarding an antimicrobial substance that targets microorganisms without harming the host would be accurately identified as antibiotics (Option A), and the suitable chemical for use on living tissues for microbial control is an antiseptic (Option B).