The answer for #1 description is Hypothesis: Redi's hypothesis is that flies can only be produced by other flies.
The answer for #2 description is Control: The control group was the meat in the container with no covering, thus leaving it open to the flies.
The answer for #3 description is Independent Variable: The independent variable is covering the meat in the container with a mesh so the flies can't get to it.
The answer for #4 description is Dependent Variable: The dependent variable is the presence of maggots on the meat that is observed in response to the independent variable.
The answer for #5 description is Constants: The constants or factors that are kept the same for both groups are the location of containers and temperature, so that it was not one of these that caused the change.