Name: _____________________________________ Date: __________ Class: ______
Review
B.7FG: Evolutionary Mechanisms and Complexity
B.7F: Analyze and evaluate the effects of other evolutionary mechanisms, including genetic
drift, gene flow, mutation, and recombination.
Supporting Standard
B.7G: Analyze and evaluate scientific explanations concerning the complexity of the cell.
Supporting Standard
1. There are five mechanisms of biological evolution: natural selection, genetic drift,
gene flow, mutation, and recombination. The molecular effects of the
mechanisms of evolution increase or decrease genetic diversity in a population.
2. Genetic Drift is the change in a gene pool due to chance; it is the change in
frequency of allele from one generation to the next and is unpredictable. It tends
to limit diversity.
3. Gene flow is the movement of alleles into or out of a population. It reduces the
gene diversity between populations, but increases the diversity within
populations (it makes populations more similar.)
4. Mutations are changes in genes and increase diversity. They are the raw
materials for evolutionary change.
5. Recombination by sexual reproduction results in new combinations of alleles and
individual genotypes in each generation. Since alleles are independently and
randomly segregated, new gametes combined in the creation of new zygotes
have genetic variation.
6. The Endosymbiotic Theory states that mitochondria and chloroplasts were once
free-living prokaryotes that formed a symbiotic relationship within eukaryotic
cells.
7. The Oparin-Haldane Hypothesis poses that organic molecules existed in a
‘primordial soup’ millions of years ago and became surrounded by a membrane
to create the first living organisms. Other hypotheses for the origin of
biomolecules include the Iron-Sulfur World Theory and RNA World.
Vocabulary
bottleneck effect, emigration, Endosymbiotic theory, founder effect, gene flow, genetic
drift, immigration, independent assortment, Oparin-Haldane Hypothesis, recombination,
Fundamental Questions
Use the Key Concepts information as well as the information in your Stemscopedia
beginning on page 75 to answer the fundamental questions below.
1. How do the mechanisms of evolution change diversity of populations?
2. Why are mutations the raw materials for natural selection?
3. How does recombination increase genetic variation?
4. What theories have been developed to explain the complexity of cells?
Analysis
Complete the following in the space provided.
1) Make a Thinking Map or Venn Diagram to compare and contrast gene flow and genetic
drift.
2) Choose whether a Bottleneck Effect has more affect on a small or large population;
defend your answer.