| A | B |
|---|
| spontaneous generation | idea stating that life could arise from nonliving matter |
| controlled experiment | a test of the effect of a single variable by changing it while keeping all other variables the same |
| manipulated variable | factor in an experiment that a scientist purposely changes; also know as independent variable |
| responding variable | factor in an experiment that a scientist wants to observe, which may change in response to the manipulated variable; also know as a dependent variable |
| theory | well-tested explanation that unifies a broad range of observations |
| biogenesis | the theory that new organisms come form existing organisms |
| Francesco Redi | performed a controlled experiment and concluded that maggots form only when flies come in contact with meat - the experiment disproved spontaneous generation |
| Anton van Leeuwenhoek | made lenses that allowed him to magnify object; described “animalcules” or tiny animals living in water. |
| John Needham | tried to prove spontaneous generation – he heated (but didn’t boil) gravy in a seal jar and microorganisms appeared in the gravy |
| Lazzaro Spallanzani | boiled two flasks of gravy – he left one flask open and sealed the other flask – microorganisms appeared in the open flask - the experiment disproved spontaneous generation |
| Louis Pasteur | boiled broth in a bent neck flask which allowed air in but kept microorganisms out of the broth – no microorganisms grew in the broth until the bent neck was removed and microorganisms were allowed to enter the broth - the experiment disproved spontaneous generation |
