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Biology
Ch 16
| Question | Answer |
|---|---|
| T/F Mendel's work on inheritance was published after Darwin's lifetime. | false |
| Which 2 important factors was Darwin unable to explain without an understanding of heredity? | He did not know the source of the variation that was so central to his theory. He could not explain how inheritable traits were passed from one generation to the next |
| 3 Fields that collaborate today to explain evolution. | 1genetics 2molecular biology 3evolutionary theory |
| A collection of individuals of the same species in a given area is a _______________ | population |
| The combined gentic information of all members of a particular population is a ________________ | gene pool |
| T/F The gene pool typically contains just one allele for each inheritable trait | false |
| The number of timmes that an allele occurs in a gene pool compared with the number of times other alleles occur is called the __________ of the allele. | relative frequency |
| Sources of Genetic Variation | 1Mutations 2Genetic Shuffling |
| What is a mutation? | any change in a sequence of DNA |
| Why do mutations occur? | because the mistakes in the replication of DNA or as a result of radiation or chemicals in the environment |
| T/F Mutations can be lmtd to a single base of DNA | true |
| T/F Mutations always affect lengthy segments of a chromosome | false |
| T/F Mutations always affect an organisms phenotype | false |
| T/F Mutations always affect an organisms fitness | false |
| T/F Most inheritable differences are due to gene shuffling that occurs during the production of gametes | true |
| T/F Sexual reproduction is a major source of variation in many populations | true |
| T/F Sexula reproduction can produce many dif. phenotypes | true |
| T/F Sexual reproduction can produce many dif. genetic combinations | true |
| T/F Sexual reproduction can change the relative frequency of alleles in a population | false |
| T/F The number of phenotypes produced for a given trait depends on how many genes control the trait | true |
| T/F Most traits are controlled by a single gene | false |
| T/F Natural selection on single-gene traits cannot lead to changes in allele frequencies | false |
| If a trait made an organisms less likely to survive and reproduce, what would happen to the allele for that trait? | It would disappear from the gene pool completely or fewer copies of an allele would be passed down to future generations |
| If a trait had no effect on an organisms fitness, what would happen to the alelle for that trait? | The allele that produces this trait will not be under pressure from natural selection, and its frequency will remain unchanged |
| 3 Ways natural selection can affect the distributions of phenotypes | 1Directional selection 2Stabilizing Selection 3Disruptive Selection |
| What is directional selection? | Individuals at one end of the curve have higher fitness then individuals in the middle or at the other end |
| What is stabilizing selection? | Individuals near the center of the curve have higher fitness than individuals at either end |
| What is disruptive selection? | Individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle |
| An increase in the average size of beaks in Galapagos finches is an example of ________ selection | directional |
| T/F The weight of human infants at birth is under the influence of disruptive selection. | false |
| T/F Natural selection is the only source of evolutionary change | false |
| Random change in allele frequencies in small populations is called ________ | genetic drift |
| A situation in which allele frequencies change as a result of the migration of a small subgroup of a population is known as the ____________ | founder effect |
| What is an example of the founder effect? | The evolution of several hundred species of fruit flies found on dif. Hawaiian Islands that descended from the same mainland population |
| What does the Hardy-Weinberg principle state? | Allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change |
| The situation in which allele frequencies remain constant is called _________ | genetic equilibrium |
| 5 Conditions req to maintain genetic equilibrium | 1Random mating 2Very large population 3No movement into/out of population 4No mutations 5No natural selection |
| Why is large population size important in maintaining genetic equilibrium | Genetic drift has less effect on large populations |
| What is speciation? | The formation of new species |
| T/F Individuals in dif species can have the same gene pool | false |
| What does it mean for 2 species to be reproductively isolated from each other? | Members of 2 populations cannot interbreed and produce fertile offspring |
| What must happen in order for new species to evolve? | Populations become reproductively isolated from each other |
| 3 Ways reproductive isolation occurs | 1behavioral 2geographic 3temporal |
| When does behavioral isolation occur? | 2 populations are capable of interbreeding but have dif. in courtship rituals or other types of behavior |
| T/F E and W meadowlarks are an example of behavioral isolation | true |
| When does geographic isolation occur? | 2 populations are separated by geographic barriers such as rivers, mountains, or bodies of water |
| Abert and Kaibab squirrels in the SW are an ex. of ___________ isolation | geographic |
| T/F Geographic barriers guarantee the formation of new species | false |
| What is an example of temporal isolation? | 2 or more species reproduce at dif times (pollination) |
| T/F The basic mechanisms of evolutionary change cannot be observed in nature | false |
| Hyp tested by Grants: T/F The finches beak size/shape -enough inheritable variation to provide raw material for nat. selection The dif. finch species are descendants of common mainland ancestor | true/false |
| Hyp tested by Grants: T/F Differences in the finches' beak size/shape produce dif in fitness that cause nat selection, The evolution of finches is proceeding slow/gradually | true/false |
| Observ. by Grants: T/F Dif. in beak size=more imp. for survival during wet season, When food for finches was scarce, individuals with the largest beaks were less likely to survie | false/false |
| Observ by Grants: T/F Big beaked birds tend to mate w/ small beaked birds, Average size beak increased dramatically | false/true |
| Speciation probably occurred in Galapagos finches | 1Founders arrive 2Separation of populations 3Changes in the gene pool 4Reproductive isolation 5Ecological competition 6Continue evolution |
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K1
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