Download Unit 8 Study Guide Answer Key

Unit 8 Evolution & Classification
Study Guide
Part 1 (LT 9, 11-12, & 17)
1.
What does a theory explain in science?
Why we see what we see in nature
2.
What does the theory of evolution explain?
The unity & diversity of life
3.
List the 8 different evidences for evolution we discussed in class.
Biogeography, Fossil Recors, Extinctions, Homologous structures, Analagous Structures, Vestigal
structures, DNA, Embryology
4.
5.
What are two ways fossil records can be dated? Briefly explain both (what isotope is used most
frequently & why).
Relative dating (older layers deeper under ground)
Radiometric dating (half-lifes of isotopes…C14 commonly used b/c plants & animals absorb it.
What is considered a mass extinction (population level)?
60% population dies
6.
Draw a timeline of the big events in earth’s history (oldest fossils? mass extinctions & when do we see a
sudden explosion of different body types?)
Prokaryotes 3.5 billions year old!! Creataceous, Triassic, Permian, Devonian, Ordovician….present time
Cambrian explosion!
7. What percentage of species that have ever lived are extinct?
99%
8. What benefit comes from extinctions?
Opens up niches for other populations
9. Define homologous and analogous structures? List at least one example for each.
Homologous similar structures because of a common ancestor (ex bat wing & whale flipper. Both
mammals & structure of bones similar…even function ->movement)
Analagous  similar function, but NOT b/c of a common ancestor (insect wing & a bat wing)
Part 2 (LT 1 & 2, 6 & 16)
10. Who recognized that the interaction of an organism with its environment was important in an evolutionary sense?
Both Darwin & Lamarck
11. What was Lamarck’s theory of evolution?
That individual organisms develop adaptions that get passed on (ex: giraffes stretching its neck longer,
passes it on…it would be like saying that you could pass on your 6-pack to your children)
12. Define “Descent with Modification”.
Descent from a common ancestor…with changes….why species are so diverse, yet still similar
13. What are three limits to Natural Selection?
Limited to existing variations (can’t select for something that’s not present
Constraints due to history (nat selection has already selected the most fit individuals…finding
something “new & improved” is difficult
Trade-off in changes (ex: cheetahs w/longer legs legs frail & break easily=death)
14. What does the term “fitness” mean?
Best able to survive and pass on genes… NOT STRENGTH!!!!
15. In order for Natural Selection to occur, what are some necessary conditions?
Not enough resources, survival of the fittest and variation in the gene pool
16. What does natural selection act directly on?
The individual (the alleles in each individual genotype)
17. How is fitness affected by human activities? Give an example.
Humans change the environment  variation that is most fit selected for….human are a selective pressure on
populations (pollution, loss of habitat, hunting, etc)
18. Define Directional selection.
Individuals at one extreme are more fit
19. What would a graph look like for a population that is going through Directional Selection?
20. Define Stabilizing selection.
Individuals in the middle are more fit
21. What would a graph look like for a population undergoing stabilization selection?
22. Define Disruptive selection.
Individuals in middle are less fit—eliminated
23. What would a graph look like for a population undergoing disruptive isolation?
Part 3 (LT 3 & 7 & 8)
24. What are two types of Genetic Drift? Explain each below.
Founder’s effect (new population will carry different allele frequencies from original population b/c only the
alleles of the “founders” of the new population will be passed on)
Bottleneck effect (when some disaster wipes out a large portion of the population and leaves only a few to
reproduce  reduces diversity)
25. What is the definition of microevolution?
A change in allele frequency
26. In gene flow, genes are being exchanged between different_____________populations________________.
27. What are three sources of genetic variation? Briefly define each. Circle the major source of variation.
Mutations mistakes in replication, rare
Gene shuffling  mesoisis & crossing over MAJOR SOURCE!!!!
Polygenic traits  Polygenic traits ->controlled by many genes
28. All of the members of a population have the same
gene pool
, which determines their
phenotypes.
29. When members of the same population interbreed, what happens to the gene pool?
No change in gene pool ….allele frequencies same
30. What would be the impact on evolution if mutations stopped occurring?
No new variations could enter a population, but frequencies of existing alleles could still change
Part 4 (LT 4 & 5)
31. What are the 5 requirements for Hardy Weinberg Equilibrium?
Large Population; Random Mating; No Natural Selection; No Migration; No Mutation
32. Write down the Hardy-Weinberg Equation & label each part Homozygous Dominant, Heterozygous, and
Homozygous Recessive.
p2 + 2pq + q2
HD (p2 ), Hetero (2pq), hr (q2)
33. As the allele frequency of p increases, what happens to q?
It decreases
34. If the dominant allele is present in a gene at a frequency of 60%, what is the frequency of the recessive allele?
40%
35. Cystic fibrosis is caused by a recessive allele. If 91% of the population does not have cystic fibrosis, what is the
frequency of the dominant allele? The recessive allele? What percent of the population is heterozygous?
91% is the Dominant geneotype 100%-91% Q2 =.09 q=.3
p+q=1  1-.3=.97  p = .97
Dominant allele (p) .97, Recessive allele (q)  .3, Hetero (2pq) .582 or 58.2%
Part 5 (LT 14 & 16)
36. List & briefly define the 5 types of prezygotic isolation.
Behavioral isolation  behavior prevents mating
Habitat/Geographic isolation  physical barrier/habitat differences or rare encounters prevent mating
Temporal isolation  mate at different times
Mechanical Isolation  morphological differences prevent mating
Gamteic Isolation  Sperm cannot survive/fuse with egg
37. List & briefly define the 3 types of postzygotic isolation
Reduced hybrid viability  hybrid dies before born or developmental impairment makes hybrid frail
Reduced hybrid Fertility  hybrid fine, but can’t reproduce
Hybrid Breakdown hybrid fine, can reproduce, but second or third generation cannot
38. Allopatric speciation results from
Geographic Reproductive Isolation_____.
Part 6 (13)
39. What is macroevolution?
Large scale changes in evolutionay patterns bigger than species
40. What is Adaptive Radiation?
Evolution of diverse species from a common ancestor.
41. Convergent Evolution?
Unrelated organisms develop similar structures
42. How does the concept of punctuated equilibrium differ from “normal” evolutionary theory?
Punctuated equilibrium says evolution can proceed both quickly and slowly.
Part 7 (15, 17-25)
43. Why do researchers think RNA came 1st?
RNA can act as an enzyme & because researchers have been able to create it in a lab
44. What evidence supports the endosymbiotic hypothesis?
Mitochondria and chloroplasts both have their own DNA, which is similar to bacteria
45. What did Miller & Urey’s experiment prove?
That conditions are early Earth were favorable enough to form molecules needed for life
46. All organisms use the same genetic code. What does that tell you about their relationship?
They share a common ancestor
47. Hemoglobin is a common protein, whose amino acid sequence is known. There are 20 amino acids different
between a dog and a rattlesnake hemoglobin structure. There are 10 amino acids different between a dog and a
coyote. Rattlesnakes and coyotes have 25 amino acids different in their hemoglobin structure. Which 2 species
are more closely related? Justify your answer (complete sentences!!)
Dog and coyote, less difference between the two
48. What distinguishes one branch from another in a cladogram?
Derived characters
49. What is an outgroup?
A group that does not have a recent common derived characteristic, used for scale
50. Using the Cladoragm above, circle a taxa.
51. Using the Cladogram above, draw a square around the sister group of turtles.
52. Using the cladogram above, draw a triangle over a common ancestor (node).
53.
Using the cladogram below, what two organisms are the closest relatives? The furthest?
Closest: flies & butterflies, furthest: Flies & beetles
54. What ancestor gave rise to both nonseeded and seeded plants in this phylogenic tree?
55. According to the phylogenetic tree to the right,
which organism would you expect to not have
an amnion (membranes around their embryos
during development)?
Lungfish & amphibians
56. Using the table, draw a cladogram of species 1-5 (hint, identify your outgroup first).
First vascular plants