Flashcards in Spontaneous Generation - Scientific Experiments Deck (39):
Name 4 scientists who studied scientific generation.
Francisco Redi, John Needham, Lazzaro Spallanzani, and Louis Pasteur
When was Redi's experiment?
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?
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?
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?
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
What was Spallanzani's responding variable?
The presence of 'animalcules'
What was Spallanzani's control group?
The unsealed flasks
What was Spallanzani's experimental group?
The sealed flasks.
What were Spallanzani's results?
The sealed jars had no life. The open jars were teeming with life.
What was Spallanzani's conclusion?
The nonliving gravy cannot produce the living 'animalcules.'
When was Pasteur's experiment?
What problem did Pasteur investigate?
Do air and dust particles influence the growth of microorganisms?
What was Pasteur's hypothesis?
If air is left in the broth because of the curvy-necked glass, then microorganisms will not appear because spontaneous generation is false.
Describe Pasteur's experiment.
He made a curvy-necked glass and left it filled with broth for a year. Then he took the neck off.
What was Pasteur's manipulated variable?
Curved neck on the glass
What was Pasteur's responding variable?
Appearance of life
What was Pasteur's control group?
What was Pasteur's experimental group?
What were Pasteur's results?
There were no microorganisms for a year in the curvy-necked glass, but once the neck was broken off, it teemed with life.