Download exam1v2sep5_2012

Exam 1 GENE/BIOL 3000
Student ID# 810________________
Please write your full name on the back of the final page.
This exam has 6 sets of problems, on 6 pages. Pay close attention to point totals in
allocating your time. NO CALCULATORS. If you aren’t comfortable with the
math, show your work as intended so we know what you were trying to do, or
explain the concept verbally.
Please answer the questions as succinctly as possible but write as legibly as possible.
We will not grade the back of the pages, so limit your answers to the space provided.
Use PEN ONLY; we will not regrade any exams written in pencil.
1. Using illustration and/or short answers, explain the four postulates underlying
Darwin’s theory of natural selection. LABEL ANY DRAWINGS CLEARLY! (3 points
each, total of 12 points)
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2. Short Answer problems, use the space provided
A. Looking at wild populations of
finches, you measure beak depth of
the parents at each nest, tag all of the
offspring that hatch from that nest,
and measure beak depth of the
offspring from each nest the
following year when they are fully
grown. You do this twice and find the
relationship shown in the graph at
right. Explain TWO other factors that
must be considered before
determining whether this trait is
heritable (4 points).
B. Two species of shrimp differ at a fraction 0.07 of the nucleotides in a particular
mitochondrial gene. One is found in the Caribbean, one in the Pacific, and a separate
analysis suggests that they are each others closest relatives. If the Panamanian Isthmus
arose 3.5 million years ago, what is the mutation rate at this gene (6 points)?
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3. True or False? Circle the correct answer (2 points each, 12 points total)
A. Natural selection influences the survival of individuals but populations change and
evolve over time
TRUE
FALSE
B. Cicada wings and bird wings are homologous
TRUE
FALSE
C. At a single locus with two alleles, an individual homozygous for allele A1 produces
white flowers, while either heterozygotes or homozygotes for allele A2 produce blue
flowers. This is an example of additive genetic variation
TRUE
FALSE
D. Phenotypic variation in a population is caused by both environmental and genetic
factors
TRUE
FALSE
E. Humans have selected for marine fishes to grow more slowly
TRUE
FALSE
F. UGA is both a university and a stop codon
TRUE
FALSE
4. Provide one-sentence definitions for the following words, but be thorough (3
points each, total of 18 points)
A. heterozygosity
B. homology
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C. paralog
D. transversion
E. irreducible complexity
F. life history
5. Short Answer problems, use the space provided
A. In the case of the major histocompatibility complex (MHC) in the human genome as
discussed in class, what are two ways that Hardy-Weinberg equilibrium is violated (4
points)?
B. In a standard deck of 52 cards, there are 4 equally represented “suits”: spades, clubs,
hearts, diamonds. If I ask you to “pick a card, any card” what is the probability you pick a
diamond? (2 points)
When your friend is asked to do the same, what is the probability that BOTH OF YOU
have picked a diamond card? (2 points)
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5B continued: What is the overall probability, before either of you pick a card, that the
two of you will have picked cards of different suits? (4 points)
Explain how these questions are pertinent to evolutionary biology (4 points).
C. Why is population size important for evolution, and derive a mathematical description
of this important role (6 points)
D. Explain why we think most mutations are deleterious. First, what type of experiment
has been used to evaluate this hypothesis? (2 points)
What is the primary difference between control and experimental conditions in this
experiment? (3 points)
What is the typical outcome of these experiments? (3 points)
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6. Multiple Choice (3 points each, 18 points total)
A. Kermode bears (white individuals of Ursus americanus) are thought to:
1.
2.
3.
4.
be the result of hybridization with polar bears
have a competitive advantage with dark-furred bears when fishing
have originated during the Oligocene
both 1 and 2 are true
B. We learned about reverse transcriptase in the HIV genome because:
1.
2.
3.
4.
RNA is damaged by this protein, preventing infection
some variants are less likely to mistake AZT for thymidine
this enzyme requires special nucleotides such as AZT for synthesis
This is responsible for the disease in contemporary banana populations
C. Selection coefficient:
1. Ranges from 0 to 1
2. Represents the proportional difference in reproduction or survival between
genotypes
3. Depends on the environment in which it is tested
4. Only meaningful for heritable traits
5. All of the above
D. Polyploidy is a result of:
1.
2.
3.
4.
transversion
speciation
genome duplication
decreased fitness
E. Not a condition for Hardy-Weinberg equilibrium to be met:
1.
2.
3.
4.
no mutation
effectively infinite population size
allelic variation
random mating
F. Alleles that are homozygous lethal persist because of:
1.
2.
3.
4.
orthology
Small fitness consequences
synonymous mutations in coding regions
when rare they are usually in heterozygotes
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