Other organisms were another factor. What kinds of changes in other populations of organisms could be affecting the moths?

When the environment changed, due to pollution, the moth population shifted because light-colored moths became easier to see so they were eaten more often. Organisms that survive have a better chance of reproducing so the population continues to grow. Human actions affect other populations.

The answer is joseph is observing the colour of the reaction mixture to see whether proteins are present in the given solution.