Tuesday, August 24, 2010

What are the control group and experimental group in this project? (It's just a paragraph.)?

Francesco Redi wanted to find out if flies spontaneously arose (came alive) from rotting meat. Redi believed that flies hatched from eggs laid by other flies, other scientists believed that meat caused flies to come alive. He set up an experiment. In the experiment he had two jars. In both jars he put a piece of meat. Over one of the jars he places a net, which allowed only air to enter the jar. He waited several days and observed the jars. In the jar without netting, there were maggots (immature flies) on the meat. In the jar with the netting, there were maggots on the net but not on the meat.





I knew a few answers, but here are three I did not:


4.What was the control group?


5.What was the experimental group?


6.Was his hypothesis proved or disproved by the experiment?


10 Points!What are the control group and experimental group in this project? (It's just a paragraph.)?
The control group had nothing manipulated. The experimental group had an experimental treatment applied (the netting).





Redi's hypothesis that flies hatched from eggs laid by other flies is proved (this is not exactly how scientific hypotheses are tested, but for this assignment this should be ok).





The hypothesis should be:


H0: There is no difference in the number of flies hatching between the two treatments: rejected.


H1: There is a difference between the number of flies hatching between the two treatments (higher with no net): accepted.





Science advances by disproving hypotheses. In this case the alternate hypothesis (H1) should be accepted and subjected to further experimentation.What are the control group and experimental group in this project? (It's just a paragraph.)?
The control group would be the jar with no net, because it is known that there will be flies with no net. This would be the positive control.





The experimental group would be the jar with the net, because some scientists believe that you would get flies/maggots without access to flies.





His hypothesis was that flies hatched from eggs laid by other flies, therefore he was right because without access to flies there were no maggots.





This isn't very hard, are you being lazy? What grade is this in?
1. The control group: he placed a net over the jar.


2. The experimental group: he did not place a net over the jar.


3. His hypothesis was proved by the experiment.
This is a little tricky because the control group doesn't seem like it should be a control group, its the one without the net. The reason being that a control group keeps all variables constant within an experiment and what changes is a single variable, the independent variable. This might have been simpler if there had been a third jar covered with seran wrap, you can see that the variable of a barrier is whats being tested and the control is the plain ol jar being open to the air.





Experimental group then was the netted jar given that the variable being changed is having a barrier vs no barrier to the outside world.





Hypothesis proved-heres a sublte distinction that you may not think is important but is essential I assure you, and any biology teacher worth his HS diploma will feel this way too. The scientists hypothesis was SUPPORTED, not proven. The distinction is that in science things arent ever proven 100%, you simply have gained evidence in support of your hypothesis or not in support. In this case the evidence he has gathered supports his hypothesis that flies hatch from eggs laid by other flies.
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