Which experimental setup did Louis Pasteur use to disprove the theory of spontaneous generation in meat broth?

• A. He placed raw meat in an open jar and observed maggot formation.
• B. He added chemicals to meat broth to kill all microorganisms and left it uncovered.
• C. He sealed meat broth in a completely airtight container without boiling.
• D. He boiled meat broth in a swan-neck flask, leaving it exposed to air but preventing dust from entering.

Answer: (D)

Verified step by step guidance

1. Understand the theory of spontaneous generation, which proposed that living organisms could arise from nonliving matter spontaneously.
2. Recognize that Louis Pasteur designed an experiment to test this theory by using meat broth, which could potentially support microbial growth if spontaneous generation were true.
3. Note that Pasteur boiled the meat broth to kill any existing microorganisms, ensuring the broth was initially sterile.
4. Observe that he used a swan-neck flask, which allowed air to enter but trapped dust and microbes in the bend, preventing them from reaching the broth.
5. Conclude that because no microbial growth occurred in the broth despite exposure to air, Pasteur disproved spontaneous generation by showing that microorganisms come from other microorganisms, not spontaneously.