Squid is an animal that is eaten in many parts of the world. The body of the squid is used as meat because it contains a lot of protein. The photograph shows some squid meat. (Source: © Ilia Nesolenyi/Alamy Stock Photo) The meat from squid is quite tough and is often treated with enzymes to break down the protein. Some fruits contain enzymes that can break down protein. Pineapples contain the enzyme bromelain and unripe papayas contain the enzyme papain. A study compared the effects of two different concentrations of these two enzymes on the meat from squid. The flowchart shows some of the steps in the method used in this study. Give two variables that need to be controlled in step 3. (1)

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