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Ch. 1 - The Microbial World and You
Chapter 1, Problem 1.8a

DRAW IT Show where airborne microbes ended up in Pasteur’s experiment. <IMAGE>

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1
Understand the context of Pasteur's experiment: Louis Pasteur conducted experiments to disprove the theory of spontaneous generation, which suggested that life could arise from non-living matter.
Recognize the setup: Pasteur used a swan-neck flask containing a nutrient-rich broth. The design of the flask allowed air to enter but trapped airborne particles, including microbes, in the bend of the neck.
Identify the key observation: When the broth was boiled and the flask was left undisturbed, no microbial growth occurred in the broth, demonstrating that microbes did not spontaneously generate.
Consider the role of airborne microbes: The microbes present in the air were trapped in the neck of the flask, preventing them from reaching the broth and causing contamination.
Conclude the significance: Pasteur's experiment showed that microbial life comes from existing microorganisms in the environment, not from spontaneous generation, highlighting the importance of airborne microbes in contamination.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Airborne Microbes

Airborne microbes are microorganisms, such as bacteria and fungi, that are suspended in the air. They can be transported over long distances and are often responsible for the spread of diseases. Understanding their behavior and distribution is crucial in experiments like Pasteur's, which aimed to demonstrate the role of these microbes in contamination.
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Number of Microbes

Pasteur's Experiment

Louis Pasteur conducted a series of experiments in the 19th century to disprove the theory of spontaneous generation. He used swan-neck flasks to show that sterilized broth remained free of microbial growth when protected from airborne contaminants, thus illustrating that microbes in the air were responsible for spoilage and contamination.
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Pasteur's Experiments on Spontaneous Generation

Contamination and Sterilization

Contamination refers to the introduction of unwanted microorganisms into a sterile environment, which can lead to spoilage or infection. Sterilization is the process of eliminating all forms of microbial life, often achieved through heat or chemical means. Pasteur's work highlighted the importance of these concepts in microbiology, particularly in food preservation and medical practices.
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Related Practice
Textbook Question

Which of the following is a beneficial activity of microorganisms?

a. Some microorganisms are used as food for humans.

b. Some microorganisms use carbon dioxide.

c. Some microorganisms provide nitrogen for plant growth.

d. Some microorganisms are used in sewage treatment processes.

e. all of the above

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Textbook Question

NAME IT What type of microorganism has a peptidoglycan cell wall, has DNA that is not contained in a nucleus, and has flagella?

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Textbook Question

It has been said that bacteria are essential for the existence of life on Earth. Which of the following is the essential function performed by bacteria?

a. control insect populations

b. directly provide food for humans

c. decompose organic material and recycle elements

d. cause disease

e. produce human hormones such as insulin

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Textbook Question

Which of the following is an example of bioremediation?

a. application of oil-degrading bacteria to an oil spill

b. application of bacteria to a crop to prevent frost damage

c. fixation of gaseous nitrogen into usable nitrogen

d. production by bacteria of a human protein such as interferon

e. all of the above

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Textbook Question

Spallanzani’s conclusion about spontaneous generation was challenged because Antoine Lavoisier had just shown that oxygen was the vital component of air. Which of the following statements is true?

a. All life requires air.

b. Only disease-causing organisms require air.

c. Some microbes do not require air.

d. Pasteur kept air out of his biogenesis experiments.

e. Lavoisier was mistaken.

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Textbook Question

Use the following choices to answer questions 9 and 10.

1. 9 + 2 flagella

2. 70s ribosome

3. fimbria

4. nucleus

5. peptidoglycan

6. plasma membrane


Which is (are) found only in prokaryotes?

a. 1,4,6

b. 3,5

c. 1,2

d. 4

e. 2,4,5

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