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Unit 8, Evolution Study Guide
Topics
History of earth:
1. Redi, Needham, Spellanzani, and Pasteur all performed experiments concerning spontaneous generation. List the
basic experimental design of each scientist. Redi – Tested how many flies appeared in the meat when the jars were open
and when they were closed. Spallanzani and Needham tested how many microbes grew in the broth of the flasks. But
in each experiment they could not find a way to allow air in and not the microbes. Pasteur was the person who finally
accomplished this with his swan necked flask and allowed air in but no mircrobes proving sponateous generation could
not occur.
2. What is meant by chemical evolution? Organic molecules formed from inorganic in the beginning of the earth.
3. Which scientists performed experiments simulating Earth’s early conditions and the formation of organic compounds
from inorganic compounds? Miller and Urey
4. In terms of the first life forms that existed on Earth, which type of organism came first, autotrophs or heterotrophs?
Heterotrophs- organisms that must obtain materials and energy.
5. Explain what is meant by (biological) evolution. Descent with modification
6. True or false, evolution can happen within a lifetime?false
7. True or false, individuals can evolve in their lifetime? false
8. How did Lamarck believe that evolution occurs? Use the example of the giraffe’s long neck to help explain your
answer. He thought that over time the giraffe’s stretched their necks to reach the food and finally they evolved to have
long necks. This is not true.
9. Explain Darwin’s theory of natural selection. In other words, how did Darwin think evolution happened. Use the
example of the giraffe’s long neck to help explain your answer. Over time those Giraffe’s with long neck breed together
and those with shorter necks died off.
Natural and Artificial Selection: (2 mechanisms for how evolution can occur)
11. In ostriches, there are 2 types: ones that run fast and those that run slowly. The fast birds can reach up to 50 miles
an hour. Jackals love to eat ostrich, and they can reach speeds of up to 35-40 miles per hour. Due to predation and
other factors, not all ostrich produced live to the age of reproduction.
a. What ostrich will natural selection select AGAINST? _______slow ostrichs___________ FOR? ________fast
ostriches_______
Darwin's points: Identify the points in the scenario above.
Overproduction (more offspring produced than survive). Overproduction of ostriches that run faster
Population has heritable variation. __the ostriches because some are slow and some are fast
Struggle to survive______those ostriches with slow running speed
Differential Reproduction (those with better variation survive and reproduce) : those birds that run the fastest.
How the population will change over time.____eventually only those that run fastest will survive
12. List all of the sources of variation that we talked about that can lead to evolution.
Mutations, gene flow, natural selection, artificial selection, genetic drift, sexual selection
13. What does fitness mean in terms of natural selection and evolution? Those organisms best suited to their
environment will survive.
14. What is an adaptation? A change in the organism due to some outside force.
15. Compare and contrast artificial and natural selection. In natural selection, “who” does the selecting of traits? In
artificial selection, who does the selecting of traits. Environment selects for traits in natural selection. Humans select
for traits in artificial selection
16. Give some examples of how artificial selection is used. Corn, broccoli, dog breeds (look at notes)
Gene Flow, Genetic Drift, Sexual Selection: (3 more mechanisms for how evolution can occur)
17. What is gene flow? Give an example of it. Migration of genes from one place to another.
18. In general, what is genetic drift and how does it lead to evolution? Gene frequency that changes by chance.
19. Compare genetic drift with natural selection in terms of how each leads to evolution. Both show changes in genetic
variation.
20. What is sexual selection. How is it similar to and different from natural selection? Sexual selection is random and is
based on who an organism chooses as a mate.
21. With sexual selection, which traits get passed on more over time? Those traits that are most favored when
reproducing.
22. Why is sexual reproduction so common despite all of its costs? Because an organism wants to pass on its traits.
Evidence of evolution
23. List and describe all the different types of evidence for evolution that we discussed.
Fossil record, embryology, anatomy, DNA, biogeography
24. What can we determine from the following piece of fossil evidence?
there was once a time when dinosaurs roamed the earth.
25. What two things does biogeography look at/compare? How does biogeography act as a source of evidence for
evolution. (hint, use the Galapagos Islands as an example).
The finches all had different beaks but they were still all finches. So there must have been some common ancestor for
the finches.
26. Label each of the following anatomy images as homologous, analogous, or vestigial, AND explain what you can
conclude based on each.
A
Homologous
B
vestigial
C
analogous
28 What form of evidence is shown below and how do we analyze it/what can we conclude from it?
Because the DNA is all similar we must have descended from
a common ancestor.
Speciation
29. What is speciation and what is the key component needed for speciation to occur? When a new species arrises
from another one. Isolation must occur.
30. The two types of isolation that we discussed are geographic and reproductive. What is geographic isolation and
what are some causes of it? What is reproductive isolation and what are some different causes of it? How can each
form of isolation cause new species to form?
Geographic isolation is when populations are split apart due to some mountain, river, or earthquake. Some physical
characteristic that separates them. Reproductive isolation is when they can no longer interbreed and therefore can no
longer produce offspring.
31. When speciation occurs due to geographic isolation, it is known as what? Allopatric speciation
32. When speciation occurs due to reproductive isolation, it is known as what? Sympatric speciation
33. Be able to make conclusions about the mating behavior of different frog species based on a diagram of frog mating
seasons (shown below). In other words, based on the diagram, be able to determine the most likely reason that certain
species of frogs don't mate.
Different mating season, different mating calls, or different anatomy.