Gifted Biology - Evolution Test Study Guide Answer Key
1. Define evolution.
Process of biological change by which descendants come to differ from ancestors
2. Define species.
Group of organisms so similar that they can reproduce & have fertile offspring
3. Compare and contrast Lamark and Darwin’s theory of evolution.
Lamarck – theory of acquired traits
Darwin – theory of natural selection
4. In terms of geology and geography, what observations did Darwin make that helped him
develop the theory of evolution?
Saw fossils and earthquakes (catastrophism)
5. What observations did Darwin make about finches on the Galápagos’ Islands?
Beaks were different shapes based on food sources
6. Explain what “survival of the fittest” means.
Organisms best adapted to their environment will live longer and have more offspring
7. What is an adaptation?
Feature that allows an organism to better survive in its environment
8. What do phenotypes have to do with natural selection?
They are the outward signs of trait…mates may be chosen based on their phenotypes
9. How do genotypes relate to evolution?
Positive adaptations have their genotypes passed down to future generations
10. How does natural selection work?
Individuals with beneficial adaptations will live longer and have more offspring
11. List and describe the four main principles of natural selection.
Variation – differences exist between members of a population
Overproduction – many extra offspring raises chance that some will survive
Adaptation – certain variations allow some to survive better
Descent with modification – over time, natural selection results in species with
beneficial adaptations
12. How are fossil, anatomy, embryology, vestigial, and genetic evidence in support of
evolution?
Fossils – showed organisms changing over time
Anatomy – similar structures indicates possible common ancestor
Embryology – similar embryos suggest possible common ancestor
Vestigial – remnant structures suggest function in older ancestor
Genetic evidence – similar DNA or proteins suggest common ancestor
13. Define variation and list the two main sources for genetic variation in organisms.
Variation – differences within population; mutation & recombination
14. In terms of sexual reproduction, what does recombination mean?
New allele combinations form through meiosis; reorganized in fertilization
15. Identify examples if stabilizing, directional, and disruptive selection.
Stabilizing – intermediate phenotype is favored
Directional – causes a shift in the phenotype distribution (left or right)
Disruptive – both extremes are favored; intermediate is selected against
16. Identify stabilizing, directional, and disruptive selection in graphical form.
Graphs on pages 331-333
17. Define gene pool. Combined alleles of all of the individuals in a population
18. What is gene flow? Movement of alleles from one population to another
19. What is genetic drift and how does it work?
Some alleles will increase or decrease in frequency due to chance
20. How do population bottleneck and the founder effect result in genetic drift?
Bottleneck – occurs when an event greatly reduces size of population
Founder – small number of individuals colonize a new area
21. Match each of the five factors influencing evolution with a brief definition.
Genetic drift – allele frequencies change due to chance
Gene flow – movement of alleles from one population to another
Mutation – new alleles are formed
Sexual selection – certain traits improve mating success…these traits increase
Natural selection – certain traits may be an advantage for survival…these traits increase
22. What is Hardy-Weinberg Equilibrium? Know the rules and how to calculate.
p2 + 2pq + q2 p2 = AA
2pq = Aa
q2 = aa
23. What conditions must be met to stop fluctuations in allele frequencies (evolution)?
Very large population, no emigration/immigration, no mutations, random mating, no
natural selection
24. What are the three main steps in speciation?
Isolation, adaptation, formation of a new species
25. What does reproductive isolation mean and how does it occur?
Members of different populations can no longer mate successfully
26. What is geographic isolation and how does it contribute to speciation?
Physical barrier divides a population into two or more groups
27. How does geographic isolation relate to gene flow?
Alleles are not able to move from one population to another
28. What is the difference between geographical, behavioral and temporal isolation?
Geographical – physical barrier
Temporal – timing barrier
Behavioral – change in signals (scents, courtship rituals, sounds, etc.)
29. What is the difference between convergent and divergent evolution? Give examples.
Convergent – evolution toward similar characteristics in unrelated species (wings)
Divergent – evolution in opposite directions (foxes in different environments)
30. What is coevolution? What is an example?
Process in which two or more species evolve in response to changes in each other
(hummingbird and tube shaped flowers)
31. How might mass extinctions encourage the rapid evolution of new species?
Many species are destroyed which encourages new species who are better adapted
32. What is adaptive radiation? How are Darwin’s finches examples?
Diversification of one ancestral species into many descendent species…finches are
adapted to many different environments