Variables

Independent variable: The time that the organs are died
How are we going to mesure this? This is going to be mesured by freezing those organs and keep them for  few hours inside that fridge , then we are going to extract the DNA and then mesure by watching it with a microscope. This is going to be repeated with other organs of animal. 

Dependent variable: The quantity of DNA that those organs produce will be the dependent variable because it depends on the time the organs still produce DNA. We will see the amount of DNA the organ produces through the experiment and then through a microscope. We will measure the amount of DNA without alcohol in grams.

Constant variable: The same quantity that we are using with all the different types of  materials. We keep the organs the same in the same environment.

Variables we cannot control: We can't control the time the organs have been dead before we buy them, and we can't know where they have been before their death.