Multiple Choice
Which experimental setup did Louis Pasteur use to disprove the theory of spontaneous generation in meat broth?
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2. Disproving Spontaneous Generation
Pasteur's Experiments on Spontaneous Generation
Multiple Choice
Pasteur used swan-neck flasks in his experiments to prove that:
A
Air is required for the growth of all microorganisms.
B
Microorganisms do not arise spontaneously but come from pre-existing life.
C
Microorganisms can grow in nutrient broth without any external contamination.
D
Boiling destroys all forms of life, including spores.
Verified step by step guidance1
Understand the historical context: Before Pasteur's experiments, the theory of spontaneous generation suggested that microorganisms could arise spontaneously from non-living matter.
Recognize the design of Pasteur's swan-neck flask experiment: The flask allowed air to enter but prevented dust and microorganisms from reaching the nutrient broth due to the curved neck trapping particles.
Analyze the outcome: After boiling the broth to kill existing microorganisms, no microbial growth occurred in the broth unless the flask was tilted, allowing trapped particles to contact the broth.
Interpret the results: This demonstrated that microorganisms do not spontaneously generate but come from pre-existing microorganisms present in the environment.
Conclude that Pasteur's experiment disproved spontaneous generation and showed that contamination from external sources is necessary for microbial growth.
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