Table of contents

1. Introduction to Microbiology3h 22m
2. Disproving Spontaneous Generation1h 18m
3. Chemical Principles of Microbiology3h 38m
4. Water1h 28m
5. Molecules of Microbiology2h 23m
6. Cell Membrane & Transport3h 28m
7. Prokaryotic Cell Structures & Functions5h 52m
8. Eukaryotic Cell Structures & Functions2h 18m
9. Microscopes2h 46m
10. Dynamics of Microbial Growth4h 36m
11. Controlling Microbial Growth4h 10m
12. Microbial Metabolism5h 16m
13. Photosynthesis2h 31m
14. DNA Replication2h 25m
15. Central Dogma & Gene Regulation7h 14m
16. Microbial Genetics4h 44m
17. Biotechnology3h 0m
18. Viruses, Viroids, & Prions4h 56m
19. Innate Immunity7h 15m
20. Adaptive Immunity7h 14m
21. Principles of Disease6h 57m

2. Disproving Spontaneous Generation

Needham vs. Spallanzani

Microbiology

2. Disproving Spontaneous Generation

Needham vs. Spallanzani

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Multiple Choice

Needham performed an experiment by boiling chicken broth, placing it in a sterile flask, and then sealing the flask. After a few days, he observed microorganism growth in the flask. What was the major flaw of his experiment?

Boiling the broth activated dormant microorganisms that were not present before boiling.

Melting the flasks closed did not allow fresh air to interact with the broth, stopping microorganisms from developing.

Needham boiled the broth too long, killing the 'vital source' needed to develop microorganisms.

He did not boil the broth long enough to kill all microorganisms and he did not seal the flask properly.

The flasks he used were cracked, and microorganisms from the air contaminated the broth.

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Verified step by step guidance

Understand the purpose of Needham's experiment: He aimed to demonstrate spontaneous generation by boiling chicken broth, sealing it, and observing if microorganisms would develop.

Consider the process of boiling: Boiling is intended to kill existing microorganisms. If microorganisms are observed after boiling, it suggests that either the boiling was insufficient or contamination occurred.

Evaluate the sealing method: Proper sealing is crucial to prevent external contamination. If the flask was not sealed correctly, microorganisms from the environment could enter and grow in the broth.

Analyze the duration of boiling: Insufficient boiling time may not kill all microorganisms present in the broth, allowing them to survive and multiply.

Identify the major flaw: The combination of inadequate boiling and improper sealing led to the presence of microorganisms, suggesting that Needham's experiment did not effectively eliminate or prevent contamination.