Dr. Reichler’s Bio 301M   MWF 9-10am    Print Name:______________KEY______________
Exam #3   May 3, 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. What part of human fear is genetically determined, and what part is environmentally determined? (8 pts)
Experiments show that we have an ingrained, genetically determined, fear of certain shapes, and other experiments show that what we fear can be manipulated by what we learn (environment).

2. If adopted children have similar abilities for playing Scrabble as their adopted parents, would this indicate a genetic or environmental basis for Scrabble ability? (8 pts)
Environmental, with no genetic relationship to their parents, the children must be picking up these skills from the environment.

3. Give a specific example of an environmental factor that affects human behavior but cannot be changed by the individual. (8 pts)
Things that occur in the womb or early childhood such as the number of older brothers.

4. Does the gap at the ends of DNA occur on the leading or lagging strand?  Explain. (4 pts)
Lagging strand.  DNA polymerase moves away from the ends on the lagging strandmaking it unable to replace the RNA primer.

5. Could insurance companies use telomere length as a reliable determining factor when issuing life insurance?  Why or why not? (8 pts)
Yes, studies in humans showed that people with shorter telomeres were more likely to die.  Telomeres get shorter by age, but also by DNA damage.
No, while there is a general correlation within one person’s lifetime of telomere length and age, it is difficult to make comparisons between people.  Also, different parts of the body have different length telomeres.

6. Describe two situations that would cause someone to have short telomeres. (8 pts)
Age causes shorter telomeres due to repeated DNA replication.  Damage to DNA also leads to short telomeres.

7. Would a virus that infected a cell with very short telomeres be able to replicate?  Why or why not? (4 pts)
No, a cell with short telomeres would be inhibited from replicating DNA.
Yes, an RNA virus could get its genetic material copied because short telomeres would not effect RNA replication.

8. Is access to plentiful food enough to increase the carrying capacity of a species?  Why or why not? (8 pts)
No, removal of waste and available space are also critical factors in determining carrying capacity.

9. What evidence indicates that the avian flu is not being transmitted by wild migrating birds? (4 pts)
Avian flu movement has moved across, or in different directions, from many migration patterns.  While some migration patterns go from Asia to the US, the avian flu has not moved into the US.

10. Why is someone who is infected with both human and avian flu strains especially dangerous for the rest of the human population? (8 pts)
When two strains of the flu infect the same cell, the strains can exchange genetic information, and in this case, might form a highly virulent flu with easy transmission between people.

11. Why would cutting down trees increase global warming? (8 pts)
Plants use CO2 from the atmosphere.  Removing plants would decrease the removal of CO2 from the atmosphere.

12. What does data about past climate change tell us about our current situation? (8 pts)
Samples from ice cores have shown several coincidences of increased CO2 levels and temperature.

13. Would you expect there to be more elk or wolves in Yellowstone NP?  Explain. (8 pts)
Elk.  The wolves are secondary consumers, and the elk primary consumers.  Because of the loss of energy as it moves through each consumer there are typically less consumers at higher levels.

14. When studying the effects of reintroducing wolves to Yellowstone NP, why did researchers measure the depth of creek and river gullies? (8 pts)
They hypothesized that the wolves were causing the elk to avoid areas with low visibility such as deep gullies.

Bonus:  Are differences in finger length thought to be related to a cause or effect of sexuality? (3 pts)
Since these differences occur in the womb, they cannot be an effect of sexuality.