20. What is the scientific definition of evolution?
A: It is the process of biological change by which descendants come to differ from their ancestors.

21. What is a species?
A: It is a group of organisms so similar to one another that they can reproduce and have a fertile offspring.

22. Name the early scientists who contributed to evolution and describe their contributions.
A: - Carolus Linnaeus: developed a classification system for organisms where he grouped them by their similarity.  He proposed that some organisms must have arose through hybridization.

- George Buffon: proposed species shared ancestors and suggested Earth was much older than 6000 years

- Erasmus Darwin: all living things descended from a common ancestor and more complex forms of life arose from less complex forms.

- Jean-Baptiste Lamarck: all organisms evolved toward perfection and complexity.  Reasoned that organisms evolved into different forms.

Lamarck's Proposal: Proposed that changes in environment caused organism's behavior to change, leading to greater use or disuse of a structure or organ.  The structure would become larger or smaller as a result. The organism would pass on these changes to its offspring which is known as the inheritance of acquired traits.

- George Cuvier: thought that organisms couldn't change but become extinct based open observing fossils.  He proposed the theory of catastrophism which states that natural disasters such as floods and volcanic eruptions have happened often before.

- James Hutton: changes he observed in land forms resulted from slow changes over a long period of time which came to be know as gradualism.

- Charles Lyell: produced the theory of uniformitarism which states that geologic forces that shape Earth are uniform through time.

23. What is variation?
A: It is the difference in the physical traits of an individual from those of other individuals in the group to which it belongs.

- Interspecific variation: among different species
- Intraspecific variation: among same species

24. What is an adaptation?
A: An adaptation is a feature that allows an organism to better survive in its environment which leads to genetic change.

25. What were a few other things that Darwin noticed on Galapagos Islands?
A: He noticed the differences between species on different islands well suites to the animals' environment.  Also, he found fossil evidence of species changing over time which made him believe that the Earth must be much more than 6000 years old.

26. What is artificial selection?
A: Artificial selection is when humans change a species by breeding it for certain traits. Darwin explored this by breeding pigeons.

27. What is heritability?
A: It is the ability of a trait to be passed down from one generation to next.

28. What is natural selection?
A: It is the mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals.

29. What did Thomas Malthus proposed and how did Darwin expand it?
A: Thomas Malthus proposed that resources such as food, water, and shelter are natural limits to population growth.  Darwin reasoned that organisms have more offspring than could ever survive.

30. What is a population?
A: It includes all the individuals of a species that live in an area.

31. Describe four main principles to the theory of natural selection.
A: - Variation: variations are the basis for natural section

- Overproduction: having many offspring raises both the chances that some will survive and would result in competition.

- Adaptation: certain variation allows an individual to survive better.

- Descent with modification: natural selection would result in well adapted species and reproduction of that species increases.

32. How is the term "fitness" used in Biology?
A: It is the measure of the ability to survive and produce more offspring relative to other members of the population.

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