Download UNR ID Number: BIOL 191 FALL 2005 Midterm 1 Form A

Print Name:
UNR I.D. Number:
BIOL 191 FALL 2005 Midterm 1 Form A
IMPORTANT: Be certain to indicate on your answer card (scantron) the form letter that
appears above (Form A or B).
Part 1, Multiple Choice (75 points); Choose the single best response (A,B,C,D or
E) to each question.
1. According to the theory of evolution put forward by Charles Darwin,
A. hereditary information is encoded by particulate factors that do not blend in
offspring.
B. individuals in a population vary in characteristics that affect their ability to survive
and reproduce.
C. genetic drift causes maladaptation in large populations.
D. organisms develop heritable adaptations through the use and disuse of
characters.
E. the DNA replicator is the fundamental unit of evolution.
2. According to the graphs below,
A. HIV strains isolated from different human hosts (patients) are identical in their
level of resistance to the drug AZT.
B. in both patients, HIV resistance to the drug AZT has increased through time
within the lifespan of the human host.
C. level of HIV resistance varies between different hosts but does not evolve in
response to AZT treatment within a host.
D. after 16 months of treatment, AZT has no effect on HIV viability in Patient 2.
E. (All of the above)
Form A, page 1
Print Name:
UNR I.D. Number:
3. Non-random mating is an evolutionary force that
A.
B.
C.
D.
E.
changes gene frequencies but not genotype frequencies.
changes genotype frequencies but not gene frequencies.
is only effective in small populations.
is only effective in large populations.
is just a theory that is unsupported by any data.
4. In a population that is in Hardy-Weinberg equilibrium for two alleles (A and a), 36%
of the individuals show the recessive trait. What is the frequency of the Aa genotype
in the population?
A. 0.24
B. 0.40
C. 0.48
D. 0.52
E. 0.60
5. Alleles that increase their transmission to the next generation by sabotaging
gametes carrying alternative alleles
A. are unknown in nature because selection always acts for the good of the species.
B. are called meiotic drive alleles.
C. are called genomically-imprinted genes.
D. are called transposable elements.
E. exhibit a mode of transmission that is best described as horizontal.
6. Negative frequency dependent selection occurs when
A.
B.
C.
D.
E.
the fitness of a genotype increases as it becomes more common.
selection favors individuals at the two extreme ends of a phenotypic distribution.
the fitness of a genotype decreases as it becomes more common.
selection favors individuals near the center of a phenotypic distribution.
genetic drift results in the fixation of common alleles in small populations.
Form A, page 2
Print Name:
UNR I.D. Number:
7. Many strains of the bacterium, Myobacterium tuberculosis, have developed
increased resistance to antibiotics over the last 20 years. What is the scientifically
best-supported explanation for how this has occurred?
A. Natural selection, acting on heritable variation existing in the original bacterial
populations, has increased the representation of resistance alleles through the
generations.
B. Genetic drift, acting in large populations, has led to the fixation of antibioticresistance alleles.
C. By increasing the mutation rate for resistance, antibiotics have generated
heritable mutations that enable bacteria to neutralize antibiotics.
D. By striving toward greater resistance, the bacteria have acquired heritable
resistance to antibiotics.
E. The evolution of antibiotic resistance remains a major unsolved puzzle in modern
biology.
8. The fundamental difference between the sexes that acts to generate more intense
sexual selection on males in the great majority of animal species
A.
B.
C.
D.
can be traced back to the effects of testosterone on fetal development.
involves greater brain development in males.
is not amenable to scientific investigation.
is a consequence of males being the heterogametic sex in all multicellular
species.
E. is a consequence of the two sexes producing gametes that differ greatly in size
and energetic content.
9. The excellent fossil record of horses shows that modern horses, which have one toe
on each foot, evolved from ancestors that had multiple toes. A trait such as the
modern horse’s single toe that differs from the ancestral trait in the lineage is called
A. a derived trait.
B. a paraphyletic trait.
C. an outgroup trait.
D. a molecular trait.
E. a primitive trait.
10. A single brother/sister pair of troglodytes escape political persecution on the planet
Zulton to establish a new population on a previously uninhabited planet. This
provides an example of
A.
B.
C.
D.
E.
autopolyploidy
founder effect.
heterozygote superiority.
sexual selection.
sympatric speciation.
Form A, page 3
Print Name:
UNR I.D. Number:
11. Scarlet macaw individuals from populations in Ecuador and Costa Rica never mate
in large aviaries (natural enclosures) even though artificial insemination experiments
demonstrate that between-population fertilizations produce viable and fertile hybrid
offspring. This provides an example of
A.
B.
C.
D.
E.
heterozygote superiority.
prezygotic reproductive isolation.
postcopulatory sexual selection.
postzygotic reproductive isolation.
sympatric speciation.
12. In the harlequin beetle riding pseudoscorpion,
A. females typically produce broods of offspring sired by several males.
B. over short time intervals between mating, females readily mate with novel males
but tend to reject previous mates.
C. females that engage in polyandry give birth to more offspring than females
restricted to mating with a single male.
D. females that engage in polyandry suffer a lower rate of spontaneous brood
abortion than females restricted to mating with a single male.
E. (All of the above).
13. Rare dispersal and colonization of an island from a mainland can result in
A.
B.
C.
D.
E.
parapatric speciation.
peripatric speciation.
sympatric speciation.
synoptic speciation.
vicariant speciation.
14. An ancestral species and some but not all of its descendent species is called
A.
B.
C.
D.
E.
a deme unit.
a monophyletic unit.
a paraphyletic unit.
a super population.
ontogeny recapitulates phylogeny.
15. A shared, derived character of the class Mammalia (mammals) is
A.
B.
C.
D.
E.
claws.
fur.
jaws.
lungs.
vertebrae.
Form A, page 4
Print Name:
UNR I.D. Number:
Part 2, Definitions (25 points) Use complete sentences to provide detailed definitions (or
descriptions) of the following terms or phrases:
1) Stabilizing selection (define and discuss its implications for evolution): refers
to selection that favors the intermediate (average or median ok) phenotype (3
points); stabilizing selection does not change the mean of a phenotypic distribution
(1 point) but it reduces the variance (1 point).
2) Genetic drift (define and point out what it does and when it might be
important): refers to changes (or alterations) in gene frequency due to chance
events (3 points). Genetic drift reduces genetic variation as the result of the
extinction (loss) of alleles (1 point) and its effects are most important in small
populations (1 point).
3) Microevolution versus macroevolution: microevolution refers to evolutionary
processes (mutation, drift, gene flow, natural selection) occurring at the population
level or below (3 points). Macroevolution refers to evolutionary changes occurring
above the species level (2 points) (e.g., speciation, diversification of lineages, mass
extinctions, etc.).
4) Sensory exploitation model of sexual selection by female choice: refers to a
situation in which males exploit pre-existing biases in the female’s sensory system to
increase their attractiveness (5 points). Give partial credit (2 points) for an example
without the definition. For example, male euglossine bees produce a pheromone
(chemical signal) that smells like an orchid. This increases the likelihood that
females will be attracted to the male because they are fooled into viewing the male
as a possible as a nectar and pollen source.
5) Monophyletic group: refers to an ancestral species and all its descendent species
(5 points). Again, give partial credit (2 points) for an example without the definition.
For example, mammals or birds but not reptiles.
Form A, page 5
Print Name:
UNR I.D. Number:
Part 3, Extra Credit (12 points)
1. Discuss the four main premises of Darwin’s theory of evolution by natural selection.
1. Many more individuals are born than survive (based on Malthus' ideas, an
economist) (COMPETITION) (3 points)
2. Individuals vary in their characteristics (phenotype) and in the struggle to survive,
some individuals are more successful than others (VARIABILITY) (3 points)
3. These survivors pass on their characteristics to future generations
(HERITABILITY) (3 points)
4. Repetition of this process generation after generation gradually transforms the
species (based on Lyell's ideas, a geologist) (ITERATION) (3 points)
Give a total of 4 points total for just the terms: competition, variability, heritability
and iteration.
Form A, page 6