Early scientists believed living matter could form spontaneously from nonliving matter. This was called spontaneous generation. To support their theory of spontaneous generation, scientists observed that if raw meat was left out in open, white maggots would appear “spontaneously”. Louis Pasteur hypothesized that living matter could not develop from nonliving matter. His experiment compared sterilized broth which he placed in two different shaped flasks. One flask had a straight tube, and the other had a s-curved tube as pictured below.
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Both tubes were open to expose the broth to the air. Pasteur observed that after several days the broth in the flask with the straight tube was cloudy and the broth in the flask with curved tube was unchanged. After testing, the cloudy broth had been contaminated with bacteria from the air. Pasture theorized that the bacteria could simply move easily to the broth through the straight tube, but the bacteria was trapped in the u-shaped area of the curved tube and could not get to the broth. His conclusion provided evidence to disprove the idea that living matter could spontaneously form from non-living matter.
Pasteur’s experiment is viewed as modern scientific inquiry. Which of the following elements of his discovery are necessary for scientific inquiry?
I. l. Begins with a hypothesis
II. ll. Tested with a controlled experiment
III. lll. All parts of the scientific method were followed in order.
The necessary elements of Pasteur's discovery for scientific inquiry are:
I. Begins with a hypothesis - In Pasteur's case, his hypothesis was that living matter could not develop from nonliving matter.
II. Tested with a controlled experiment - Pasteur conducted an experiment comparing two flasks with different shapes of tubes to see if bacteria would contaminate the broth. This was a controlled experiment as he had two flasks with only one variable (the shape of the tube).
III. All parts of the scientific method were followed in order - The scientific method typically involves several steps: making observations, formulating a hypothesis, conducting experiments, analyzing data, and drawing conclusions. While the specific steps of the scientific method may vary in different experiments, Pasteur's discovery followed a similar order. He made observations about the differences in the two flasks, formulated a hypothesis about how bacteria could be trapped in the curved tube, conducted the experiment to test the hypothesis, analyzed the results (cloudy broth in the straight tube), and drew a conclusion that living matter could not spontaneously form from nonliving matter.
Therefore, all three elements of scientific inquiry (hypothesis, controlled experiment, and following the scientific method) are present in Pasteur's discovery.