Spontaneous Generation - Scientific Experiments Flashcards
Name 4 scientists who studied scientific generation.
Francisco Redi, John Needham, Lazzaro Spallanzani, and Louis Pasteur
When was Redi’s experiment?
1668
What was the problem that Redi studied?
Do flies produce maggots?
What was Redi’s hypothesis?
If maggots appear on meat after a couple of days, then flies produce them, because they lay eggs too small for humans to see.
Describe Redi’s experiment.
He placed jars with meat out and covered half with gauze, effectively keeping flies out.
What was Redi’s independent variable?
The gauze on the jars
What was Redi’s dependent variable?
Maggot appearance
What was Redi’s control group?
The jars without gauze
What was Redi’s experimental group?
The jars with gauze
What were Redi’s results?
He discovered that the meat exposed to flies was covered in maggots, but the other meat did not.
What were Redi’s conclusions?
He concluded that flies lay microscopic eggs on meat, thus producing maggots.
When was Needham’s experiment?
Mid 1700’s
What problem did Needham study?
Spontaneous generation can occur under the right circumstances.
What was Needham’s hypothesis?
If I heat gravy until all life may have died, then “animalcules” will spontaneously generate.
Describe Needham’s experiment.
He heated a sealed container of gravy, assuming that he killed off all life. He looked inside to find out whether or not life was there.
What was Needham’s independent variable?
Heat (of the gravy)
What was Needham’s dependent variable?
Presence of ‘animalcules’
Did Needham have a control group?
No
What were Needham’s results?
There was life in the gravy.
What was Needham’ conclusion?
Life can spontaneously generate.
What problem did Spallanzani investigate?
Does the gravy need to be hotter (than Needham’s) to kill the ‘animalcules?’
What was Spallanzani’s hypothesis?
If I heat up gravy and kill all of the ‘animalcules,’ then no more will form, because spontaneous generation is false.
Describe Spallanzani’s experiment.
He boiled two sets of glasses of gravy and sealed half. He made sure that no animalcules were left and waited for more.
What was Spallanzani’s manipulated variable?
The seal on the glasses
