| A | B |
|---|
| evolution | The process of how organisms acquire adaptations over time is called _____ |
| ancestor | An organism from which others have descended is referred to as an _____ |
| 3 billion | Scientists believed that the first life appeared over _____ years ago. |
| cladogram | Another word for a branching diagram is a _____. |
| sedimentary | The rock layers from which most fossils are dug are _____. |
| base sequences | DNA is used as evidence for evolution because species with more similarities in their _____ are more closely related than those with fewer similarities. |
| embryos | By studying the _____ of a fish, calf, and rabbit, scientists can conclude that they all come from a common ancestor. |
| adaptation | A hummingbird's long beak helps it get nectar from flowers. This is an example of an _____. |
| common ancestor | Darwin hypothesized that the different finches on the Galapagos Islands all had a _____. |
| artificial selection | When breeders produce changes in a species on purpose, they are using _____. |
| variations | Without _____ in a population evolution could never occur. |
| extinction | Increased competition with other species, newly introduced predators, loss of habitat, and catastrophes all may lead to _____ of a species. |
