Show where microbes ended up in Pasteur’s experiment.

Verified step by step guidance

1. Step 1: Understand the setup of Pasteur's experiment, which involved two flasks with nutrient broth—one with a straight neck and one with a swan-necked flask that prevented airborne microbes from reaching the broth.
2. Step 2: Recognize that in the swan-necked flask, dust and microbes from the air get trapped in the bend of the neck, preventing them from contaminating the broth inside the flask.
3. Step 3: Note that in the straight-necked flask, airborne microbes can directly enter the broth, leading to microbial growth and contamination.
4. Step 4: Identify that microbes ended up in the broth of the straight-necked flask, causing it to become cloudy due to microbial growth, while the broth in the swan-necked flask remained clear because microbes were trapped and could not reach the broth.
5. Step 5: Conclude that Pasteur’s experiment demonstrated that microbes come from the environment (airborne contamination) and do not spontaneously generate in the broth, as shown by the presence or absence of microbes in the two different flasks.

Key Concepts

Pasteur's Swan Neck Flask Experiment

This experiment used flasks with long, curved necks to allow air in but prevent microbial contamination. The design trapped dust and microbes in the neck, demonstrating that microbes did not spontaneously generate but came from the environment.

Microbial Contamination and Growth

Microbes are present in dust and air particles. In Pasteur’s experiment, microbes settled in the bend of the swan neck, preventing them from reaching the sterile broth, which remained free of microbial growth unless the flask was tilted.

Disproving Spontaneous Generation

Pasteur’s experiment showed that without exposure to external microbes, sterile nutrient broth remained free of life. This disproved the idea that life could arise spontaneously from non-living matter, supporting the germ theory of disease.