Explain how variable and controlled parameters are used in scientific experiments.

Ok, suppose you have an experiment in which you want to see how the variable X affects the variable Y.

In this experiment, you can change the variable X and see how the other changes, and you may understand in this way how those two variables are related. Suppose that the variable X is the weight of a car and Y is the speed of the car (X is the independent variable, and Y is the dependent variable)

Now, we can change the weight and see how the speed changes in consequence. Here we also have the "controlled parameters" that are other variables that we have fixed during the experiment, in this case, we can define things like the shape of the car, the hardware, etc as controlled parameters (we even can do the same experiment again with little changes in those parameters, and in this way find the optimal combination).

there was no answer choices but i think its representative

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.