To study possibility, the scientist uses two groups of people who are over 75 years of age and have mild memory loss. The control group receives 100 pills that contain fish oil. The group receives similar pills that don’t contain any active ingredients. These fake pills are called placebos.

Part a - which gene to compare? in this exercise, you will use the cytochrome c oxidase i (coi) gene to investigate relationships among salmon species. (this gene encodes a protein that functions in the mitochondrial electron transport chain.) you will compare the coi gene sequences from your salmon test samples to the standard sequences for each salmon species. in order for the coi gene to be useful for distinguishing among the different salmon species, which three statements must be true?