Download Evolution Study Guide Part 2

Evolution Study Guide #2
Name
Period
Answer the following questions RSQ unless the questions asks for a list or has a fill in the blank spot.
1. Read and highlight important information: Generally, organisms contain two sets of genes, one contributed by each
parent. Specific forms of genes called alleles may vary between individuals. Examples of alleles for eye color include
blue (b), brown (B), green (g), etc. An organism’s genotype is the particular combination of alleles it carries for a
trait. An individual’s genotype, together with environmental conditions, produce its phenotype. Phenotype
includes all physical, physiological, and behavioral characteristics of an organism, such as eye color or height.
Natural selection acts directly on phenotype, not genotype. This works because in populations some organism’s
adaptations, or fitness, allow the organism to survive and produce more offspring. The result of natural selection,
though, is a change in allele frequency because of phenotype. The pressures from the environment select for
survival. Pressures from the environment may include temperature, color of background, presence of water,
predation, etc.
2. Does natural selection operates on phenotype, genotype, or alleles?
.
3. What is the definition of a gene pool? (page 483)
4. Describe allele frequency and how the frequency of alleles relates to evolution.
5. Do dominant traits always become more common in a population? (Think about human populations- brown hair,
blue eyes, etc). (page 483)
Notes: What are the three main sources of genetic variation?
1. Mutations- changes in the genetic material (base pairs). Each of us is born with approximately 300 mutations.
These mutations can be neutral (no effect), negative (possible disease), or beneficial. Mutations are important for
evolution only if they are mutations in the germ cells because these genes pass onto future generations.
2. Genetic Recombination and Sexual Reproduction is the most common way of genetic variation. Remember each
chromosome pair moves independently during meiosis. In humans, who have 23 pairs of chromosomes, this
process can produce 8.4 million gene combinations! Even more combinations if crossing-over is considered.
3. Lateral Gene Transfer- not important for human evolution, but extremely important to single-celled organisms.
Lateral gene transfer is the transfer of genetic material to from one individual to another individual. Many of these
organisms do not reproduce by sexual reproduction, so lateral gene transfer provides variability or diversity of the
population. Bacteria have three main methods of lateral gene transfer where bacteria can “pick” up new genessome with important survival coding ability. Lateral gene transfer is the main mechanisms of antibiotic resistance.
6. Define single gene trait and provide one example7. Define polygenic traits and provide one example-
Note: Blood type is an example of polygenic traits – ABO
8.
Write steps to explain the process of how insect populations become resistant to pesticides. (Use your knowledge
of natural selection to help). (page 487)
9. Fill in the table of methods of natural selection (page 489)
Selection Type
Definition
Example
Graph
Directional
Stabilizing
Disruptive
Fill in the correct type of selection
A brown mouse survives on the brown forest floor more often
A medium gray insect survives on the gray rocks, but the white and black insects are reduced in population because they
are more visible
A population of finches with many types of beaks over times is reduced to those with small beaks due to the availability
of small seeds and large beaks because of the availability of large seeds. Those with intermediate size beaks have a
difficult time feeding
10. Define genetic drift: (page 490).
11. What causes the bottleneck effect?
12. THINK: Why might endangered species be more likely to “suffer” from the bottleneck effect and be more likely to
go extinct?
13. Describe the founder effect using the example in the book.
14. Define species:
15. Summarize below each of the isolating mechanisms that may cause speciation. Provide examples for each type.
(page 494-495)