In the experiment, the independent variable is the drug amount. Experiment group is given certain amount of drug, control group is not given the drug. The dependent variable is the body fat. I think you means the control is the living environment including food and water.
Hello There!
This is called the "IRIS"
The iris is the colored part of they eye and it's responsible for focusing light onto the cornea.
Homeostasis is maintained through feedback because when one certain parameter of your body goes out of the homeostatic bounds, feedback mechanisms will message this back towards the regulatory mechanisms which are responsible for homeostasis maintenance in the first place. Another thing, other than death, which can happen would be a higher bodily temperature for example.