biology exam

1. How are the comet orchid and the sphinx moth an example of convergent evolution?

   • They evolved together, with the orchid developing a long nectar spur and the moth evolving a long proboscis to reach it. This mutual adaptation shows convergent evolution, where unrelated species develop similar traits due to similar ecological pressures.

2. How would you test the hypothesis that trees compensate for having the Sun more commonly on one side than the other?

   • Measure and compare tree growth on different sides (e.g., thicker branches or more leaves on the sunnier side) in various locations to see if there’s a consistent pattern.

3. What do patterns in nature suggest to an inquiring mind?

   • They suggest underlying rules or principles, like natural selection, that shape life and its adaptations.

4. What was the Great Chain of Being and why was it initially created?

   • A hierarchical system placing all life forms in a ranked order, from simple to complex, created to align with religious beliefs about a divine order.

Lecture 02

5. Describe the process known as “inheritance of acquired characteristics” from Lamarck’s incorrect theory of evolution. How was it thought to work?

   • Lamarck thought organisms could change traits during their lifetime (e.g., giraffes stretching their necks) and pass these changes to offspring.

6. How does natural selection differ from the inheritance of acquired characteristics as an explanation of evolution?

   • Natural selection works on genetic variation already present, favoring traits that improve survival and reproduction, rather than traits acquired during life.

7. How were the geologic eras that describe the history of life on Earth (Precambrian, Paleozoic, Mesozoic, and Cenozoic) determined?

   • By studying fossil records and major extinction events that mark significant shifts in life forms.

8. How was the relative age of the fossil determined? How was the absolute age of the fossils determined?

   • Relative age: Based on rock layer position (superposition).

   • Absolute age: Determined by radiometric dating (e.g., carbon dating).

9. Provide an example of the environmental influence on phenotype.

   • Fur color in arctic foxes changes with seasons due to temperature and daylight variation.

10. What are the common types of fossils typically found?

• Bones, teeth, imprints, amber-trapped organisms, and petrified wood.

11. Define: Superposition

• In undisturbed rock layers, the oldest rocks are at the bottom, and newer ones are on top.

12. Why isn’t there a good fossil record of jellyfish?

• They lack hard parts (bones, shells), making fossilization rare.

Lecture 03

13. What are some of the basic patterns of life that are revealed by the fossil record?

• Species change over time, mass extinctions occur, and new species arise.

14. What is the importance of transitional fossil forms in the study of evolution?

• They provide evidence of gradual changes between ancestral and modern species (e.g., Archaeopteryx shows bird-reptile traits).

15. What is the importance of the science of taxonomy as started by Linnaeus to the study of evolution?

• It classifies organisms based on similarities, hinting at common ancestry.

16. Define:

• Vestigial traits: Useless or reduced structures from ancestors (e.g., human tailbone).

• Ring species: Populations connected by gradual changes but can’t interbreed at extremes.

• LUCA: Last Universal Common Ancestor, the shared ancestor of all life.

Lecture 04

17. How was the concept of mutation thought to be in direct opposition to Darwin’s idea of natural selection?

• Early scientists thought mutations were random and too sudden, conflicting with Darwin’s idea of gradual change.

18. How did observations of excess reproductive potential and conservative economic theory (Malthus) contribute to Darwin’s concept of natural selection?

• More offspring are born than can survive, leading to competition, with only the best-adapted individuals surviving.

19. How did vestigial organs, artificial selection, and fossils suggest evolution had occurred?

• Vestigial organs: Show past adaptations that lost function.

• Artificial selection: Humans breeding traits show that traits change over time.

• Fossils: Show species changes and connections between old and modern life.

20. Describe the five parts of Darwin’s original theory:

• Evolution: Life changes over time.

• Common Descent: All life shares ancestors.

• Gradualism: Changes occur slowly.

• Population Speciation: Variation leads to new species.

• Natural Selection: Favorable traits increase survival.

Lecture 05

21. Describe Industrial Melanism in the Peppered Moth.

• Dark moths became common when pollution darkened trees; natural selection favored their camouflage.

22. Describe the evidence from finches after the 1977 Galapagos drought.

• Birds with larger beaks survived better due to tough seeds, proving natural selection.

23. What does it mean when a trait is considered adaptive?

• It increases an organism’s survival and reproduction chances.

24. What is adaptive radiation? Provide an example.

• When species rapidly diversify into different environments (e.g., Darwin’s finches).

25. Why are there so many Drosophila species in Hawaii?

• Many niches allowed flies to diversify through adaptive radiation.

26. What drove finch speciation in the Galapagos?

• Different food sources led to different beak shapes.

27. Why didn’t the original finch species on South America’s coast undergo similar speciation?

• Stable environment with less pressure for adaptation.

Lecture 06

28. Why are small marine invertebrates good for studying evolution in fossils?

• They fossilize well and show detailed evolutionary changes.

29. Define: living fossils

• Species that have changed little over millions of years (e.g., horseshoe crabs).

30. Describe selection types:

• Directional: Favors one extreme (e.g., longer giraffe necks).

• Stabilizing: Favors the middle (e.g., human birth weight).

• Disruptive: Favors both extremes (e.g., large and small beak sizes).

Lecture 07

31. What ecological theory explains why moose get larger further north?

• Bergmann’s Rule: Larger animals retain heat better.

32. What research showed tree height isn’t why giraffes have long necks?

• Studies found they often eat at shoulder height and fight for mates.

33. Why do female giraffes also have long necks?

• Sexual selection likely played a role for both genders.

Lecture 08

34. Difference between categorical and continuous traits?

• Categorical: Discrete (e.g., Mendel’s peas).

• Continuous: Range of values (e.g., height).

35. Why do recessive traits disappear in F1?

• Dominant allele masks it; it reappears in F2.

Lecture 09

36. What did Hardy-Weinberg find?

• Allele frequencies stay constant unless influenced by evolution.

37. What does p² + 2pq + q² describe?

• Frequency of genotypes in a population.

38. What does 1/10,000 PKU births mean for genotype?

• q² = 1/10,000, so q can be calculated.

Lecture 10

39. What is genetic drift?

• Random allele changes in small populations.

40. Define: bottleneck & founder effects

• Bottleneck: Drastic population reduction.

• Founder: Small group starts a new population.

41. Example of founder effect?

• Tristan de Cunha’s isolated genetic traits.

42. Most likely outcome of a mutation in a gene?

• Neutral or harmful effect.

Lecture 11

47. Define:

• Gene pool: The total genetic diversity in a population.

• Phenotype: Observable traits of an organism.

• Genotype: The genetic makeup of an organism.

• Gradualism: Evolution occurs slowly over long periods.

• Darwinian fitness: An organism’s ability to survive and reproduce.

• Heritability: The proportion of trait variation due to genetics.

• Macroevolution: Large-scale evolutionary changes (e.g., new species).

• Microevolution: Small genetic changes within a population.

• Adaptive radiation: Rapid diversification into different environments.

• Homologous chromosomes: Paired chromosomes with corresponding genes.

• Alleles: Different forms of a gene.

• Sexual dimorphism: Physical differences between sexes.

• Lekking: Males gather in an area (lek) to display for females.