Part a what is a transitional fossil? what is a transitional fossil? a transitional fossil is in the middle of a direct lineage stretching from ancient forms to organisms alive today. transitional fossils were poorly adapted to their environments. transitional fossils have features that are intermediate between ancestors and descendants. transitional fossils only existed for a short period of time.

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?