How do facultative anaerobic bacteria differ from obligate aerobes and obligate anaerobes?

• A. They can grow in both the presence and absence of oxygen.
• B. They are killed by the presence of oxygen.
• C. They only grow in environments with high salt concentrations.
• D. They require oxygen for growth and cannot survive without it.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the definitions of the three types of bacteria based on oxygen requirements: facultative anaerobes, obligate aerobes, and obligate anaerobes.
2. Step 2: Recall that obligate aerobes require oxygen for growth and cannot survive without it because they rely on aerobic respiration.
3. Step 3: Recognize that obligate anaerobes are harmed or killed by the presence of oxygen because they lack the enzymes to detoxify reactive oxygen species.
4. Step 4: Know that facultative anaerobes can grow in both the presence and absence of oxygen because they can switch between aerobic respiration when oxygen is available and anaerobic metabolism when it is not.
5. Step 5: Compare these characteristics to identify that facultative anaerobes differ by their metabolic flexibility, allowing growth with or without oxygen, unlike obligate aerobes and obligate anaerobes.