Instructions: Choose the best answer. You can check your answers by clicking on "see the answers" at the bottom of the page. I highly suggest that you practice with these questions, read the chapters in the book related to the material, and go to the textbook's website to take the practice quiz for each of the chapters that your notes correspond to (http://www.brookscole.com/biology_d/).
1-3. Use the following description to answer the questions.
A population of pine trees is located near
the coastline. Some individuals in the population
have a trait that causes their needles to
grow longer than the other individuals in the population.
The long-needled trait is an advantage over
the short-needled trait because those trees with
long needles are better at shading out other
trees, and, thus, reducing competition for water near their
roots. The frequency of the long needled
trait is 75%, the frequency of the short-needled trait is
25%. During the next year a hurricane
comes ashore and removes 1/3 of the population.
After the hurricane, the frequency of long-needled
individuals is 34% and short-needled
individuals is 66%.
1. The change in the frequency of the long-needled and short-needled
traits over time is
a. evolution
d. directional selection
b. genetic drift
e. disruptive selection
c. stabilizing selection
2. The process that led to an increase in the frequency of short-needled
trees in the 2nd year was?
a. evolution
d. directional selection
b. genetic drift
e. disruptive selection
c. stabilizing selection
3. If the trees remain undisturbed for many generations, which of
the following processes are likely to
cause a change in the frequency of long vs. short needled trees?
a. stabilizing selection b. genetic drift
c. directional selection d. disruptive
selection e. both b and c
4. Gene flow can have a large or small effect on the frequency
of traits in the new population depending on?
a. the direction of change in disruptive selection
d. the number of individuals in the population
b. how often the new individual breeds in
the population
e. both b and d
c. the difference in generation time between
two species
5. Allopatric speciation is the most common mode of speciation
because it?
a. provides a barrier to gene flow
b. occurs in populations that are adjacent
to each other
c. occurs in populations that are found in
the same area
d. occurs in populations that are isolated
from each other
e. both a and d
6. The common ancestors of many large mammals (such as horses
and camels) originated in North America, some populations migrated to
Siberia via the Bering land bridge, those populations became geographically
isolated from the populations in North America, the land bridge disappeared
due to rising sea levels, the populations in North America eventually went
extinct while the populations in Siberia survived to develop into the current
species of large mammals. What model of speciation accounts for the
development of new species after the land bridge disappeared?
a. temporal isolation
b. sympatric
c. mechanical
d. parapatric
e. allopatric
7. Polyploidy in plants can lead to rapid reproductive isolation
through?
a. changes in the number of chromosomes
d. both a and c
b. how many seeds are produced
e. none of the above
c. gametic reproductive isolation
8. When DDT (a pesticide=kills insects, particularly mosquitoes)
was first introduced, insects were very susceptible to it. However,
over time, insects ìdevelopedî resistance to this pesticide.
The development of resistance to DDT by insects was the result of?
a. special mutation created by the DDT
b. natural selection on insects that already
had resistance to DDT (survived to reproduce) vs. those that did not have
resistance (died
before reproducing)
c. allopatric speciation
d. inheritance of the resistance during a
mosquitoís lifetime.
9-10. Sickle cell anemia is a serious disease in humans that causes the red blood cells to change shape (sickle) and results in a reduced ability of the red blood cells to carry oxygen to the cells of the body. People with sickle cell anemia are homozygous recessive for the trait (aa), and usually die before they are old enough to reproduce. People who are heterozygous for the trait (Aa) also suffer some of the effects, but not to the extent of those that are homozygous recessive (aa). People who are homozygous dominant for the trait (AA) do not suffer any effects of sickle cell anemia. The AA and aa traits are considered the extremes, while the Aa is the intermediate form (since they do have some effects of the trait). In regions of the world where the disease malaria is present (malaria is the 3rd leading cause of death in these regions), people who have the trait Aa are at an advantage (survive longer than individuals with AA or aa), individuals with aa are at a disadvantage because of sickle cell anemia (die before reproducing), and individuals with AA are at a disadvantage due to death from malaria. In regions where malaria is present the frequencies of individuals with each trait in the human population are approximately 30% AA; 50% Aa; and 20% aa. In regions where malaria is not present the frequency of individuals in the human population with each trait is approximately 60% AA; 30% Aa; and 10% aa.
9. Which process is responsible for the change in the frequency
of the sickle cell allele in areas with malaria?
a. evolution
d. stabilizing selection
b. genetic drift
e. directional selection
c. disruptive
selection
10. Which process is responsible for the change in the frequency
of the sickle cell allele in areas without malaria?
a. evolution
d. stabilizing selection
b. genetic drift
e. directional selection
c. disruptive
selection