Dr. Reichler’s Bio 301L MWF 9-10am Print
Exam #2 October 25, 2006
Read each question carefully and don’t hesitate to
ask if a question seems unclear. If possible, answer each
question in the space provided, but if needed, continue on the
back. If you use a drawing as part of your answer, be sure to
also include a written explanation. These questions have specific
answers, although for some, more than one answer is possible. To
receive full credit you must clearly and fully answer the question
being asked. This exam is worth 103 points with the points for
each question noted in parentheses.
1. Are the data on birth weight and finger length in agreement with
each other in regards to male sexuality? Why or why not? (8 pts)
The data agree. Both show
changes in the trait in homosexual subjects with additional older male
biological siblings. Birth weight declines and so does the
index:ring finger ratio with older male biological siblings.
2. Using twin studies, researchers showed that IQ is not purely
environmentally determined. What additional evidence showed that
genes have an effect on mental aptitude? (8 pts)
Flies with mutations in certain genes
showed impaired ability to learn.
3. What is one difference and one similarity between human’s reaction
to people of different skin colors and our reaction to spiders? (8 pts)
Similarity: The fear of spiders
and people of different skin color remained after the negative
reinforcement was removed (they both seemed to be fear relevant).
Difference: Given a different
group identity, people ignored skin color, but there is no way to make
spiders fear irrelevant.
4. If in the past some African men migrated to Asia and had offspring
with the Asian women, would you expect to see evidence of this in the
mitochondrial DNA? Why or why not? (4 pts)
No, mtDNA is only passed on through
mothers. So the African men would not have contributed any mtDNA
to the Asian population.
5. How does determining the oldest common ancestor of humans disprove
the “Multiregional” or “Out of Africa” hypotheses? (8 pts)
The hypotheses differ in the time of
initial migration from Africa, and thereby the time of our oldest
6. Would you expect identical twin voles to have similar or different
reproductive behaviors? Explain. Would it matter if they
grew up in different environments? (8 pts)
Similar reproductive behaviors.
Monogamy and non-monogamy is primarily determined by receptors to
oxytocin/vasopressin, and the twin voles have the same DNA and
therefore the same reproductive behaviors. Changing the
environment will not change their genes, and will not change their
7. Would introducing sterile male voles be an effective population
control in prairie or montane voles? Why or why not? (8 pts)
In prairie voles it would be more
effective because they are monogamous, and the females might stay with
their mate even if they are not able to reproduce. Montane voles
are non-monogamous and therefore it would not wark because the females
will likely mate with several males.
(Alternate answer) The prairie
voles may only be socially monogamous, and therefore the females may
have EPCs which would allow them to reproduce.
8. Male seahorses incubate their developing offspring in a pouch.
Why would this change the male seahorse’s perspective on monogamy? (4
The male seahorses are limited in how
many offspring they can have at a time, therefore they put more
resources into reproduction, more like females of other species.
9. Would you expect males in a non-monogamous species to have
relatively large or small testicles compared to males from a monogamous
species? Explain. (8 pts)
Large. They need to make enough
sperm to compete with other males that the females are mating with.
OR Small. If they are
physically larger than other males they may be able to physically
compete for access to females, and therefore not need to have sperm
10. When would a female looking for good genes be willing to accept an
EPC (extra pair copulation) with a male that is not her partner? (8 pts)
Her partner may not have the best
genes, and so she might except an EPC from a male with better genes.
11. What is a male behavior that would be evolutionarily favorable for
females? Explain. (8 pts)
Helping care for the offspring,
providing resources for the offspring, would help increase the
probability of successful offspring.
12. How could wearing strong perfume or cologne cause someone to choose
an incompatible mate?
Female humans can detect compatible
HLA genes by odor. A strong perfume might mask the smell of an
13. Would siblings have the exact same HLA genes? Why or why not?
No. We inherit the different
HLA alleles from each parent, and each parental gamete is unique so
that each offspring has unique combinations of genes.
14. Why do seedlings not germinate when exposed to far-red light? (8
Any one of: They can detect
that they are in the shade of another plant. This is poor quality
light for doing photosynthesis. Phytochrome, which needs to be
activated for seedling germination, is inactive in FR.
Bonus: If a plant lacked phytochrome would it grow taller or
shorter? Why? (3pts)
Taller. Phytochrome must be
activated by R to cause the plant to grow shorter. Without
Phytochrome there is not signal to grow shorter.