Download Evolution Study Sheet

Natural Selection Unit Study Sheet
Key Terms
acquired characteristics
adaptation
adaptive radiation
allele
biodiversity
continental drift
genotype
divergence
evolution
fossil
fossil record
gene flow
gene pool
phenotype
genetic drift
geographic isolation
gradualism
macroevolution
mass extinction
microevolution
selective pressures
mutation
natural selection
punctuated equilibrium
speciation
species
gene
Reading Assignments
Biology: Chapters 10, 11.1-11.3, 11.5-11.6, 12.1
Life Science: p.292-319, 324-48
Biology.com Activities (Chapters 14 & 15)
1. www.biology.com
2. Click on Biology book (left w/ iguana eye)
3. Click on Web Site
4. Login: bioyang, Password: tigers09
5. Click on Biology book again
6. Click on assigned unit, then assigned chapter
7. Practice online assessment.
Study Questions
1. Why don’t hybrids make new species? What 2 conditions must be true for a group of organisms to be
considered the same species?
2. Give examples of why individuals do not evolve.
3. How has life changed on earth? What evidence do we have for this change?
4. Draw examples of gradualism versus punctuated equilibrium.
5. Why is genetic variation so important for the survival of species?
6. How are microevolution and macroevolution different from each other?
7. What is geographic isolation? How does it contribute to evolution?
8. Describe how new species are formed.
9. What are the four factors that Darwin identified for natural selection?
10. Why is Lamarck’s evolution by acquired characteristics flawed?
11. What is the main reason for the extinction of a species?
12. What is a mutation? How does it affect evolution by natural selection?
13. How are natural selection, gene flow and genetic drift different from each other?
14. Describe how genetic drift can have negative effects on a population. How can it contribute to extinction?
15. Does evolution act on the genotype or the phenotype? Why?
State Standards Addressed:
7a. Students know why natural selection acts on the phenotype rather than the genotype of an organism. 7b.
Students know why alleles that are lethal in a homozygous individual may be carried in a heterozygote and thus
maintained in a gene pool.
7c. Students know new mutations are constantly being generated in a gene pool.
7d. Students know variation within a species increases the likelihood that at least some members of a species
will survive under changed environmental conditions.
8a. Students know how natural selection determines the differential survival of groups of organisms.
8b. Students know a great diversity of species increases the chance that at least some organisms survive major
changes in the environment.
8c. Students know the effects of genetic drift on the diversity of organisms in a population.
8d. Students know reproductive or geographic isolation affects speciation. e. Students know how to analyze
fossil evidence
The Role of Genes
** An organism’s appearance is called the __________. The traits depend on the __________, which is written
as 2 letters, or __________, the different forms of a __________. Organisms who have at least one capital
letter will express the __________ trait. Organisms who have both lowercase letters, they will express the
__________ trait.
** Evolutionary changes require changes in the __________ of a population. This means that events must
occur that cause the frequency of __________ to change. If a population has a majority of individuals brown
hair, their genotype may be ______. However if half the __________ alleles, or capital letters, disappeared
within the population, future generations will have fewer __________ haired individuals and more __________
haired individuals. The number of __________ alleles is now less than before. Therefore the __________
__________ has changed. These changes will usually occur due to changes in the mechanisms of evolution.
Variations
** Evolution will not occur unless there are __________, or small differences of the same _________, within a
population. The main cause of these are __________, or random changes in DNA. If these differences build up
over time and keep multiplying, then __________, or the development of a new __________, can result. This
means that populations have become so different from each other they can no longer __________ with each
other and produce __________ __________.
Flash Card Questions
1. What are an organism’s biological goals?
2. What is evolution?
3. What are adaptations?
4. What was Lamarck’s explanation of evolution called?
5. What was Darwin’s explanation of evolution called?
6. What are the 4 principles in Darwin’s explanation?
7. What is the difference between biodiversity and genetic variety?
8. What is the difference between an adaptation and a variation?
9. What is the term for all the genetic variations in a population?
10. Biodiversity describes the variation of this:
11. Genetic variety describes the variation of this:
12. How are changes in the gene pool significant in evolution?
13. How do adaptations affect a population?
14. What are the 2 sources of variations?
15. What are the steps to speciation?
16. Name the 3 mechanisms of evolution.
17. How does a new variation show up in a population?
18. What are the 3 barriers to reproduction?
19. Which of the evolutionary mechanisms will less likely lead to speciation? Why?
20. How does genetic drift affect a population’s variation? Why?
21. How can genetic drift lead to extinction?
22. What is the result of genetic drift?
23. What is the result of gene flow?
24. What is the result of natural selection?
25. How does gene flow prevent speciation?
26. Why is genetic variation beneficial to population?
27. What causes natural selection to happen?
28. What causes gene flow to happen?
29. What causes genetic drift to happen?
30. According to natural selection, why do species go extinct?
31. Does evolution act upon genotype or phenotype? Why?
Answer Key
1. survive & reproduce
2. All the changes that have transformed life over time
3. Characteristics that increase chances of survival or reproduction
4. acquired characteristics
5. natural selection
6. 1.) There is genetic variety in a population. 2.) Organisms tend to overproduce offspring & must compete
for limited resources. 3.) The ones that are better adapted survive & pass on their variations. 4.) The
descendants are modified because the adaptations add up and unfavorable variations disappear over time.
7. Biodiversity is the variety of many species in an area. Genetic variety refers to variations within one
species/population.
8. An adaptation is a helpful variation. Variations are different forms of one trait. They can be either helpful
or not helpful.
9. gene pool
10. variation of different species in an area
11. variation of genetic makeup in a gene pool
12. Changes in a population can lead to variations and changes to future generations
13. Adaptations lead to a better suited species.
14. mutations, genetic recombination in gametes
15. 1.) A population is geographically isolated. 2.) Adaptations in new environment add up over many
generations. 3.) Isolated group is reproductively isolated and can no longer reproduce w/ original group.
16. natural selection, gene flow, genetic drift
17. mutations
18. 1.) DNA doesn’t match. 2.) Courtship behaviors aren’t recognized. 3.) Reproductive structures don’t match.
19. gene flow; populations will have similar alleles in their gene pools
20. Random event removes/decreases a certain type of variation from the population. Less variation decreases
likelihood of adaptations.
21. If the random event kills a certain phenotype that was better adapted to the environment, then an
environmental change can kill the remaining, less suited organisms, leading to extinction of the entire
species.
22. Genetic drift decreases variations, which can lead to extinction of the species if there is no adaptation.
23. Gene flow increases variation in a population, so speciation is less likely to happen.
24. Gene flow makes populations more similar because they will have similar alleles.
25. Natural selection increases the chances of speciation if separated group becomes reproductively isolated
from the original species.
26. More variations within a population increase chances that at least a few members of the species can survive
different environmental changes, which keeps the species alive.
27. selective pressures from the environment
28. introduction of alleles to an isolated population
29. random event
30. They can’t adapt.
31. phenotype; Phenotype determines who survives & reproduces to pass on their alleles to future generations.