1. What does it mean for evolution to be a scientific theory? How does this differ from the
everyday use of the word “theory”?
2. Why does evolution act on populations rather than individuals? What role do generations
play in evolutionary change?
3. Why is the statement “humans evolved from monkeys” incorrect? How does common
ancestry clarify this misconception?
4. Why does evolution not have a goal or direction? What factors actually shape
evolutionary outcomes?
5. How does the “chicken or egg” question illustrate evolutionary thinking about ancestry
and gradual change?
6. How did Darwin’s observations during the HMS Beagle contribute to his theory? Why
were finches particularly important?
7. How does fossil position in rock layers indicate relative age? Why are gaps in the fossil
record expected?
8. How do transitional fossils support the idea of common ancestry?
9. Why did early fossil evidence for human evolution appear incomplete, and how was this
later addressed?
10. What distinguishes homologous structures from analogous structures? What does each
indicate about evolutionary relationships?
11. How do vestigial structures provide evidence for evolution despite reduced or lost
function?
12. Why are similarities in early embryonic development significant? Why do these
similarities sometimes disappear later in development?
13. How does geographic isolation promote speciation? Why do island species often
resemble nearby mainland species?
14. How does plate tectonics help explain fossil distributions across continents?
15. Why do closely related species share more DN? Why is DNA evidence stronger than
anatomical similarity alone?
16. How do shared pseudogenes or endogenous retroviruses provide strong evidence of
common ancestry?
17. What four conditions must be met for natural selection to occur? Why does the absence
of any one condition prevent selection?
18. Why does natural selection act on phenotypes but affect genotypes?
19. How does directional selection change a population over time? What environmental
conditions favor this type of selection?
20. Why does stabilizing selection reduce variation? Why are extreme phenotypes selected
against?
21. How can disruptive selection increase variation? Why can it contribute to speciation?
22. What does Hardy–Weinberg equilibrium represent? Why is it considered a null model?
23. Why does any deviation from Hardy–Weinberg assumptions indicate evolution is
occurring?
24. Why are recessive phenotypes useful for calculating allele frequencies? What does q²
biologically represent?
25. What do p², 2pq, and q² represent in a population? Why can allele frequencies remain
constant even if genotype frequencies change?
26. Why does a change in allele frequency—even without visible trait change—indicate
evolution?
27. How does genetic drift differ from natural selection? Why is drift more pronounced in
small populations?
28. What causes the bottleneck effect? How does it reduce genetic diversity?
29. What is the founder effect? Why can it cause rapid evolutionary change?
30. How does gene flow affect genetic diversity within a population? How does it affect
differences between populations?
31. Why is mutation the ultimate source of genetic variation? Why does mutation alone
rarely cause rapid evolution?
32. How does non-random mating alter genotype frequencies without changing allele
frequencies?
33. What conditions are required for speciation to occur? Why is reproductive isolation
essential?
34. How does allopatric speciation occur? What role do physical barriers play?
35. How can sympatric speciation occur without geographic isolation? Why is this more
common in plants?
36. What is the difference between prezygotic and postzygotic barriers? Give an example of
each.
37. Why are mules sterile despite having parents from two viable species?
38. What does a phylogenetic tree represent? What does it not represent?
39. Why do all species at the tips of a phylogenetic tree exist at the same time?
40. How do you determine which species share the most recent common ancestor?
41. Why does physical similarity not always indicate close evolutionary relationships?
42. Why are prokaryotes considered the earliest life forms? How did they shape Earth’s early
atmosphere?
43. Why are archaea often found in extreme environments, and why are they evolutionarily
significant?
44. How does horizontal gene transfer accelerate evolution in prokaryotes?
45. Why are prokaryotes essential to the carbon and nitrogen cycles? What would happen to
ecosystems without them?
46. How does antibiotic use drive natural selection in bacteria? Why is antibiotic resistance
considered an evolutionary and population genetics problem?