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1. The more similar the cytochrome C sequence, the closer the relation. In order from most closely related to least related: mouse, donkey, carp, corn, euglena.
2. Tail, limb buds, and pharyngeal arches
3. A butterfly wing and a bird wing are examples of analogous structures because they do not arise from a common ancestor.
4. The leaves of a cactus have been modified into spines, and the Venus flytrap’s “mouth” is also a modified leaf. The spines and the “mouth” are examples of homologous structures in plants.
5. The lower the sediment layer, the older the fossilized species.
6. A previous question listed the percent similarities between different organisms and a human:
We are mammals, so it makes sense that the two mammals on the list—a mouse and a donkey—would be our closest relatives. A carp (fish) isn’t a mammal, but it is a vertebrate, so it is definitely related to us. A plant (a multicellular eukaryote like us) is next, leaving the single-celled protist (Euglena) as our most distant relative.
7. What is the relationship between homologous and vestigial structures? A vestigial structure is a homologous structure in a species that is no longer functional.
8. What is the driving force behind the development of analogous body structures? The two unrelated organisms have similar features because they live in a common environment. Their analogous body part was an adaptation for this common environment.
9. Hutton’s theory of gradualism stated that geological structures were formed through slow changes over long periods of time.
10. b. Though every one of those traits would be evidence of common ancestry, the most reliable evidence is similarities in genetic code (since it is the “root” of the other listed traits).