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Which of the following is not an evolutionary trait that helped humans to survive and flourish? a. opposable thumbs b. exceptional sensory powers c. complex brains d. the ability to walk upright Most of what we know of the earth's life history comes from a. fossils. 2. b. DNA analysis. c. ice cores. d. chemical analysis. Evolution refers to a. changes in an individual's traits over time. b. the survival of the fittest. 3. changes in a population's genetic makeup through successive c. generations. d. extinction of species that can no longer compete. 4. ______ is the term used to describe the small genetic changes that occur in a population. a. The theory of evolution b. Macroevolution c. Chemical evolution d. Microevolution Genetic variability in a population arises through a. mutation. 5. b. genetic drift. c. gene flow. d. natural selection. In order for natural selection to occur a. the trait must not be heritable. 6. b. there must be uniformity for a trait in a population. c. the trait must lead to differential reproduction. d. offspring must be larger than their parents. 7. Which of the following processes involves changes in the gene pool of more than one species? a. convergent evolution b. diversifying selection c. coevolution d. mutation Ecologists say that a niche is like a species' ______, while habitat is like its ______. a. appearance; physiology 8. b. occupation; address c. family history; occupation d. education; occupation A species' realized niche is ______ than its fundamental niche. 9. a. smaller b. larger A(n) ______ always has a narrow niche. 10. a. keystone species b. generalist species c. alien species d. specialist species Which of the following is a specialist species? a. tiger salamanders 11. b. housefly c. raccoon d. white-tailed deer The first phase of speciation is a. background extinction of predators. 12. b. reproductive isolation. c. geographic isolation. Biologists estimate that ______ of the species that ever existed are now extinct. a. 10 percent 13. b. 30 percent c. 50 percent d. 99 percent How does a mass depletion differ from a mass extinction? During a mass depletion, populations are reduced but species do a. not become extinct. 14. Mass depletions involve fewer species extinctions than do mass b. extinctions. Mass depletions involve more species extinctions than mass c. extinctions. d. Mass depletions are local, whereas mass extinctions are global. True or false? Extinctions caused by human events will be counterbalanced by the evolution of new species. 15. True False True or false? Genetic engineering allows scientists to cross-breed different species. 16. True False Traditional artificial selection is 17. a. the process of cross-breeding species. b. now possible because of genetic engineering. the process of breeding to change the genetic characteristics of a c. population. d. the same as cloning. Which of the following is not a concern about genetic engineering? a. It is too expensive to apply genetic engineering to agriculture. 18. b. It is unpredictable. c. It raises privacy and ethical issues. d. It may harm the environment in ways we cannot foresee. ______ is the process of using genetically engineered animals as biofactories for producing drugs, hormones, chemicals, and human body organs. a. Breeding 19. b. Cloning c. Natural selection d. Biopharming 20. The ability to apply genetic engineering to extending the human lifespan raises questions about a. human population control. b. costs. c. health insurance coverage. d. safety.