If mold contains a substance that kills bacteria, then which of the following best describes this substance?

• A. It is a nutrient required for bacterial growth.
• B. It is a toxin that only affects fungi.
• C. It is a viral enzyme.
• D. It is an antibiotic.

Answer: (D)

Verified step by step guidance

1. Understand the context: Mold is a type of fungus, and it can produce substances that affect other microorganisms such as bacteria.
2. Recall the definition of an antibiotic: An antibiotic is a substance produced by microorganisms (like molds or bacteria) that kills or inhibits the growth of other microorganisms, especially bacteria.
3. Analyze the options given: A nutrient required for bacterial growth would support bacteria, not kill them; a toxin that only affects fungi would not kill bacteria; a viral enzyme is related to viruses, not molds or bacteria.
4. Identify that the substance produced by mold that kills bacteria fits the definition of an antibiotic because it inhibits or kills bacterial growth.
5. Conclude that the best description of the substance is that it is an antibiotic.