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62 Cards in this Set
- Front
- Back
Evolution |
- Genetic change in a population of organisms over time (generations) - Darwin proposed that natural selection was the mechanism of evolution |
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Adaptation |
Any peculiarity of structure, physiology or behavior that promotes the likelihood of an organism's survival and reproduction in a particular environment |
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Variation |
- Enters a population through mutation - Without variation, a population cannot evolve - Selection, artificial or natural, can only work on variation that exists in a population |
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Fossil |
- The preserved remains, tracks, or traces of once-living organisms - Created when organisms become buried in sediment - Most fossils are skeletons - Contains the most direct evidence of evolution |
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Sedimentary Rock |
- Organisms are fossilized when they are buried in sediment - We don't have fossil remains of many organisms because they were never buried in sediment |
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Molecular Clock |
A mechanism for determining the relatedness of organisms by comparing the number of differences in crucial organic molecules |
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Vertebrate |
- A backbone made of bony segments called vertebrate (found in animals) - All vertebrate embryos, including humans, have pharyngeal pouches (these develop into gill slits in fish) and a rudimentary tail (in humans all that remains of this tail is the coccyx - Similar bone structure is seen in different species of vertebrates |
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Embryo |
- Formed by the division of the fertilized egg - All vertebrates have similar embryos, indicating that the instructions for early development are critical and have not evolved major differences |
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Homologous Structure |
- A human arm and a bat wing are “homologous” - Have different functions but similar structures as a result of descending from a common ancestor - Homology due to descent from a common ancestor is the result of “divergent” evolution |
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Analogous Structure |
- Similar structures due to parallel evolution - When organisms evolve in the same environment, they may evolve structures that have similar functions |
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Vestigial Organ |
- Organs that are genetically determined, but have lost much of their ancestral function in a given species, but have nonetheless retained those processes through evolution - Examples include the human appendix and the pelvis of a whale |
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Convergent Evolution |
- Parallel evolutionary adaptations to similar environments - Results in analogous structures |
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Mutation |
- A permanent change in the dna of an organism - Occurs in DNA - Will lead to alterations in a protein |
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Migration |
The movements of individuals or alleles into or out of a population |
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Allele Frequency |
Refers to how many people in a population carry a particular allele |
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Genetic Drift |
- Random loss of alleles which can cause drastic changes in a small population - If only a few members of the population carry certain alleles, and they die or are lost or fail to reproduce, then these alleles are lost from the population |
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Founder Effect |
Occurs when a few individuals leave one population and become the foundation of a new population |
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Nonrandom Mating |
- Individuals mate with each other preferentially in a nonrandom way - Occurs in populations where, either by choice or geographic isolation, there is little mating outside the population - Can cause an unusually high allele frequency for specific alleles in a population |
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Natural Selection |
A natural process whereby the conditions in the environment determine which organisms survive and reproduce |
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Artificial Selection |
Intentional selection of breeding partners based on desired characteristics |
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Species |
A group of organisms that can breed successfully in nature and produce fertile offspring |
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Population |
- Consists of all the organisms in an area that are of the same species - In a population, more individuals are produced than can survive - Members of a population compete for limited resources |
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Isolating Mechanism |
- Make it difficult/impossible for organisms of same species to breed - Over time (with unique processes of natural selection occurring in different groups) this leads to speciation |
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Speciation |
- Involves successive change: first, local populations become increasingly specialized - If they become different enough, natural selection may act to keep them that way |
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Reproductive Isolation |
- Populations whose members do not mate with each other or who cannot produce fertile offspring - Belong to different species |
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Prezygotic Isolating Mechanism |
Mechanisms that prevent the formation of a zygote (fertilized egg) |
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Geographic Isolation |
Members of a species are physically separated and cannot breed |
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Ecological Isolation |
Members of a species in an area are localized to a particular part of the habitat, and so do not breed |
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Behavioral Isolation |
Courtship and mating rituals may differ and prevent breeding |
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Temporal Isolation |
Different breeding seasons prevent breeding |
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Mechanical Isolation |
Structural differences between organisms prevent them from breeding |
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Sickle-Cell Anemia |
- Hereditary disease - The sickle cell allele causes abnormal red blood cells - Homozygous for the sickle cell allele – usually die - Heterozygous – make enough normal red blood cells (normal hemoglobin) to function - Very common in parts of Africa |
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Stabilizing Selection |
Selects the heterozygote advantage (heterozygotes are resistant to malaria) |
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Disruptive Selection |
- Acts to eliminate the intermediate phenotype - The intermediate phenotype is less able to survive |
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Directional Selection |
- Acts to eliminate one extreme - Genes for this extreme become less available... phenotypic range shifts |
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What type of evolution is a MAJOR EPISODE OF EXTINCTION? |
Macroevolution |
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What type of evolution is THE APPEARANCE OF A NEW SPECIES? |
Macroevolution
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What type of evolution is NATURAL SELECTION RESULTING IN ALLELE FREQUENCY CHANGE IN POPULATION? |
Microevolution
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What is a trait that gives an organism a survival advantage over other organisms? |
Adaptation
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How do most adaptations arise? |
As random, spontaneous mutations |
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How does the theory of punctuated equilibrium differ from the theory of gradualism when considering the pace of evolution? |
Punctuated equilibrium proposes that evolutionary events occur in spurts, while gradualism proposes that evolution is a gradual, ongoing process
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Which theory includes the idea that there may be long periods of time without evolution? |
Punctuated equilibrium
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What are the preserved remains of dead organisms called? |
Fossils
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Fossils are created when an organism becomes buried in ..... |
Sediment
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Which layer of rock is the oldest in sedimentary rock? |
The bottom layer
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How does sedimentary rock allow the dating of fossils? |
Determines the age of the rock |
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What is a molecular clock? |
A mechanism for determining the relatedness of organisms by comparing the number of differences in crucial organic molecules |
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In a molecular clock, will organisms that are closely related have A FEW or MANY AMINO ACID DIFFERENCES in their proteins? |
Few |
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Did organisms that are closely related diverge RECENTLY or DISTANTLY? |
Recently
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What types of structures are similar in structure but not in function? |
Homologous
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What types of structures are similar in function but not in structure? |
Analogous
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What types of structures are a result of covergent evolution? |
Analogous
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What term describes organs that are remnants of a useful organ in a previous ancestor? |
Vestigial
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The wing of a bat and the arm of a human are ______________. |
Homologous
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The flippers of penguins and dolphins are ______________. |
Analogous |
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The human appendix is an example of a ____________________. |
Vestigial organ
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What is the definition of a mutation? Does a mutation occur in DNA or in proteins? |
A permanent change in the DNA of an organism; a mutation occurs in DNA, but will lead to alterations in a protein |
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List 4 mechanisms that can cause a change in the allele frequency of a population |
- Migration - Genetic drift - Nonrandom mating - Selection |
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The movement of individuals into or out of a population is called _____________ |
Migration
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List and describe two types of genetic drift |
- Founder effect occurs when a few individuals leave a population and become the foundation for a new population - Bottleneck effect occurs when many individuals in a population die and a few individuals survive to form the basis of the next generation |
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The amish community marries preferentially within their own community, limiting their gene pool and increasing the allele frequencies of several negative traits. This behavior is called ________________ |
Nonrandom mating
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How does artificial selection differ from natural selection? Which type of selection has had the greatest influence on evolution? |
- Artificial selection occurs when organisms are intentionally chosen for breeding because of their traits; in natural selection organisms with advantageous traits are not chosen, but have a better chance to survive and therefore to reproduce. - Natural selection |