Name three oxygen-tolerance categories and give an example organism type for each.

Name three oxygen-tolerance categories and give an example organism type for each.

• A. Aerotolerant bacteria; microaerophiles; capnophiles with examples.
• B. Microaerophiles; facultative anaerobes; aerotolerant.
• C. Obligate aerobes; microaerophiles; facultative anaerobes with examples.
• D. Obligate aerobes (Pseudomonas); obligate anaerobes (Clostridium); facultative anaerobes (Escherichia coli).

Answer: (D)

Understanding how bacteria handle oxygen means recognizing three clear categories: some organisms require oxygen to grow, some are harmed by it and have to grow without it, and some can grow with or without oxygen by switching their metabolism. The best choice names these three categories and pairs them with classic examples that illustrate each mode of growth: Pseudomonas is a well-known obligate aerobe, needing oxygen; Clostridium is a classic obligate anaerobe, unable to tolerate oxygen; and Escherichia coli is a textbook facultative anaerobe, capable of growing with oxygen or without it by using different metabolic pathways. This combination shows a distinct, widely taught spectrum of oxygen tolerance with familiar organisms. Other options mix in categories like capnophiles or don’t provide a clear organism for each category, which doesn’t present three standard oxygen-tolerance categories with standard examples.

Understanding how bacteria handle oxygen means recognizing three clear categories: some organisms require oxygen to grow, some are harmed by it and have to grow without it, and some can grow with or without oxygen by switching their metabolism. The best choice names these three categories and pairs them with classic examples that illustrate each mode of growth: Pseudomonas is a well-known obligate aerobe, needing oxygen; Clostridium is a classic obligate anaerobe, unable to tolerate oxygen; and Escherichia coli is a textbook facultative anaerobe, capable of growing with oxygen or without it by using different metabolic pathways. This combination shows a distinct, widely taught spectrum of oxygen tolerance with familiar organisms. Other options mix in categories like capnophiles or don’t provide a clear organism for each category, which doesn’t present three standard oxygen-tolerance categories with standard examples.