Biology Chapter 10

2. the process of forming new and distinct species.
4. structure a structure that seems to have no function in an organism and is thought to be left over from the evolutionary process.
8. anatomy the study of similarities and differences in the anatomy of different species.
10. structure organs that are similar in different organisms and are thought to show evolutionary relationships.
11. timescale a system that relates evolutionary history to rock layers in the geologic column.
13. bang the event described by the big bang theory, which states that the universe began in a very dense and very hot state and then rapidly expanded.
14. selection the human practice of breeding organisms that have desirable traits and variations.
15. radiation the change that occurs when a population spreads out into new environments.
16. ancestor an ancestral organism whose offspring diverged into two or more species.
18. fossil a fossil of an accepted age that is used to assign an age to a rock ;auer om the geologic column.
20. the preserved remains or trace of an organism that lived in the past.
22. evolution a slow, gradual change in the genetic material and proteins of organisms.
23. dating a process that analyzes radioactive elements in rocks and uses the rate at which these elements decay to calculate a sample’s age.
24. a heritable trait that improves the reproductive success of an organism.

1. the theory that suggests that the currently observable processes have occurred at the same rate in the past as they do in the present.
3. selection the process by which some phenotypes within a species become more common than others because of variations that lead to increased survival rates.
5. any primate in the family Hominidae. Evolutionary theory includes modern humans and the extinct supposed predecessors of humans in this group.
6. evolution the idea that organisms can slowly change over time into other kinds of organisms.
7. barrier anything that prevents two species or two populations of the same species from interbreeding.
9. dating the process of estimating the age of rock strata above and below a given sternum.
12. ecology the study of changes in animal behavior due to ecological pressure.
17. synthesis a modern evolutionary theory stating that changes within populations of organisms are due to natural selection and mutations.
19. with modification Darwin’s idea that all organisms come from common ancestors and change a little with each generation.
21. clock a technique that uses rates of molecular change to calculate the point in the past in which two species diverged.