Ch. 14
How Biological Diversity Evolves
Name ___________________
Period _____
California State Standards covered by this chapter:
Evolution
7. The frequency of an allele in a gene pool of a population depends on many factors and may be stable or unstable
over time. As a basis for understanding this concept:
a. Students know why natural selection acts on the phenotype rather than the genotype of an organism.
b. Students know why alleles that are lethal in a homozygous individual may be carried in a heterozygote and
thus maintained in a gene pool.
c. Students know new mutations are constantly being generated in a gene pool.
d. Students know variation within a species increases the likelihood that at least some members of a species will
survive under changed environmental conditions.
8.
Evolution is the result of genetic changes that occur in constantly changing environments. As a basis for
understanding this concept:
a. Students know how natural selection determines the differential survival of groups of organisms.
b. Students know a great diversity of species increases the chance that at least some organisms survive major
changes in the environment.
c. Students know the effects of genetic drift on the diversity of organisms in a population.
d. Students know reproductive or geographic isolation affects speciation.
e. Students know how to analyze fossil evidence with regard to biological diversity, episodic speciation, and
mass extinction.
Read the appropriate section in the textbook and lecture notes before answering the following questions. You
must put all answers and definitions into your own words for full credit.
Macroevolution and the Diversity of Life
1. macroevolution:
2. speciation:
Origin of Species
3. How does the biological species concept define a “species”?
4. In what way is the understanding of the biological concept of species important for understanding the
theory of evolution?
5. How do prezygotic barriers isolate the gene pools of species?
6. How do postzygotic barriers isolate the gene pools of species?
7. Describe each prezygotic barrier that can lead to speciation and give a specific example.
Prezygotic Barrier
Description
Specific Example
a) Temporal
isolation
b) Habitat isolation
c) Behavioral
isolation
d) Mechanical
isolation
e) Gametic isolation
8. hybrid:
9. Describe each postzygotic barrier that can lead to speciation and give a specific example.
Postzygotic Barrier
Description
Specific Example
a) Hybrid
inviability
b) Hybrid sterility
c) Hybrid breakdown
10. allopatric speciation:
11. Describe some causes of geographic isolation:
12. The more mobile an animal, the more formidable a new geographic barrier must be for
___________________ speciation to lead to different species on opposite sides of the barrier.
13. sympatric speciation:
14. polyploidism:
15. Explain the theory of punctuated equilibrium.
16. What evidence exists to support this theory?
17. How does the punctuated equilibrium model account for the relative rarity of transitional fossils
linking newer species to older ones?
Earth History and Macroevolution
18. Where are most fossils found?
19. The type of rock formed by fine particles, such as mud and sand, that contains many fossils is
________________________________.
20. trace fossils:
21. geologic time scale:
22. How is the relative age of a fossil determined?
23. radiometric dating:
24. What is the “half-life” of a radioactive isotope?
Look at the drawing of layers of rock. Each letter stands for a fossil find. Answer the following
questions about the drawing.
D
A
C
B
25. Which fossil, the one at point A or point B, is older? Explain.
26. Which fossil, the one at point A or point D, is older? Explain.
27. Compare the relative ages of fossils found at point A and point C. Explain your answer.
28. Compare the relative ages of fossils found at point B and point C. Explain your answer.
Carbon-14 is a radioactive isotope with a half-life of 5,600
years. Use figure 1 to answer the following questions
regarding Carbon-14.
Figure 1. The decay rate of Carbon-14
29. You have found a fossil while digging in your
backyard. You take it to a local paleontologist who uses
radiometric dating on it. The levels of carbon-14
indicate that it is approximately 29,000 years old. How
many half-life reductions have occurred since the
organism died?
30. You find another fossil (lucky you). It is determined that there have been 3.5 half-life reductions
since the organism died. How old do you estimate the fossil to be? (Show all math work!)
31. A paleontologist estimates that when a particular rock formed, it contained 12 mg of the radioactive
isotope potassium-40. The rock now contains 3 mg of potassium-40. The half-life of potassium-40
is 1.3 billion years. From this information, you can conclude that the rock is approximately how
old? (Show all math work and put a box around your answer.)
32. If the half-life of iodine-131 is 8 days, how long will it take a 50.0 g sample to decay to 6.25g?
(Show all math work and put a box around your answer.)
33. mass extinction:
34. Of all mass extinctions, those marking the end of the Permian and Cretaceous periods have been the
best studied. Although a great numbers of species are lost, how does a mass extinction affect
evolution of life afterward?