Dr. Reichler’s Bio 301L   MWF 9-10am    Print Name:_____________KEY_______
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 common ancestor.

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 behavior.

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 pts)
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 competition.

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?
(8 pts)
Female humans can detect compatible HLA genes by odor.  A strong perfume might mask the smell of an incompatible mate.

13. Would siblings have the exact same HLA genes?  Why or why not? (4 pts)
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 pts)
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.