Pasteur Disproved Spontaneous Generation by Demonstrating That Microorganisms Did Not

question 236

Multiple Choice

Pasteur disproved spontaneous generation by demonstrating that microorganisms did not grow in broth that was heated in swan-neck flasks and then allowed to sit undisturbed for several days.It was important that he placed the broth in control and experimental flasks before heating rather than transferring the broth to new flasks after heating.Why?

• A) The experimental design relied on having the flasks sit undisturbed for an extended time period.
• B) An additional variable could have been introduced into the experiment by including the transferring step.
• C) Microorganisms could have been introduced from the air into the broth during transfer or could have been present in the second flask.
• D) A different flask could have affected the results, so it was important to use only one flask for each sample.
• E) It was critical to have the same volume of broth before and after heating, and the transfer process could have resulted in a loss in volume.

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