Define all the following terms.
1. Evolution - the process by which modern organisms have descended from ancient organisms.
2. Fossils -preserved remains of ancient organisms.
3. Relative dating -a technique used in determining the age of a fossil using the proper sequence of formation of rocks or by comparing it to fossils of known age.
4. Radioactive dating - a technique used in determining the age of a fossil using the half-life of a particular radioactive element found in that fossil.
5. Isotopes - atoms of an element that have more neutrons.
6. Law of Superposition - a principle used in relative dating that states that in an undeformed sequence of sedimentary rock, the lower layer is older than the one on top of it.
7. Principle of Horizontal Originality - a principle used in relative dating that states that layers of sediment are deposited in a horizontal position.
8. Natural Selection - it is a process in which nature selects the trait that allows an organism to survive in its environment.
9. Artificial Selection - it is a process in which nature provides the variation among different organisms, and humans select the variations which they find useful.
10. Natural variation - differences among individuals of a species.
11. Struggle for existence - members of each species compete regularly to obtain food, living space, and other necessities of life.
12. Fitness - the ability of an individual to survive and reproduce in its specific environment.
13. Adaptation - any inherited characteristic that increases an organism's chance of survival.
14. Descent with Modification - a principle which states that living species have descended, with changes, from other species overtime.
15. Homologous structures - structures which have different mature forms but develop from the same embryonic tissues.
16. Vestigial organs - organs in an organism's body that do not serve important functions.
17. Gene -a sequence of protein that codes for a particular trait.
18. Gene pool - the collection of genes of a given population.
19. Mutation - any change in the sequence of the DNA.
20. Gene shuffling - the shuffling of genes that happens during sexual reproduction.
21. Polyploidy - a condition in which an organism has excess chromosomes.
22. Single-gene traits - traits that are controlled by a single gene with two alleles.
23. Polygenic traits - traits that are controlled by two or more genes.
24. Allele - another expression or form of gene that codes for a particular trait.
25. Directional selection - the effect of natural selection on polygenic traits that favors organisms with "extreme" (end of the curve) traits to survive. This would lead to a development of more species with one phenotype (outward characteristics).
26. Stabilizing selection -the effect of natural selection on polygenic traits that favors organisms with intermediate or "middle" traits to survive.
27. Disruptive selection - the effect of natural selection on polygenic traits that favors organisms that have both "extreme" traits. This would lead to the development of two phenotypes.
28. Allele frequency - the relative number of times that an allele appears in a particular gene pool.
29. Genetic drift - the sudden change in the gene pool of a population that is brought about by chance.
30. Speciation - the process by which new species are formed.
31. Reproductive Isolation - is a phenomenon that happens when a group from a species are isolated from the main group but are able to reproduce.
32. Behavioral isolation - a phenomenon that happens when two species are not able to mate because of differences in their courtship rituals.
33. Temporal isolation - a phenomenon that happens when two species are not able to mate because of differences in their mating seasons.
34. Geographical isolation - a phenomenon that happens when two species are not able to mate because of a geographical barrier that separates them.
35. Mass extinction - a pattern of macroevolution that happens when around 90% or more of a species become extinct because of natural causes such as volcanic activity, meteor collision, ect.
36. Convergent evolution - a pattern of macroevolution that happens when two or more organisms evolve similar body parts because a single cause or reason.
37. Coevolution - a pattern of macroevolution that happens when two organisms evolve because of the changes that happen to both of them.
38. Adaptive radiation - a pattern of macroevolution that happens when an individual species evolve into different species.
39. Punctuated equilibrium - a pattern of long, stable periods of inactivity interrupted by brief rapid changes.
40. Hox genes - "master control genes" that control the development of embryos.
