Dr. Reichler’s Bio 301M   MWF 9-10am    Print Name:_________KEY___________
Exam #2   March 28, 2007

    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. How could changing your eating habits have an effect on global warming? (6 pts)
Energy is lost in each consumer.  Eating plants instead of meat uses less resources including less fossil fuels, and burning fossil fuels increases atmospheric CO2 which increases global warming.

2. CO2 is released into the atmosphere by certain activities and taken out of the atmosphere by other activities.
a) What are two changes that would reduce CO2 output?  Describe what you would change, and why that would reduce CO2 emissions. (6 pts)
Any two of:  Increase energy efficiency- much of the energy produced is lost.  More efficicent use of energy would mean less burning of fossil fuels.  Use more non-fossil fuel energy sources such as solar, bio-fuels, or nuclear- burning fossil fuels releases CO2 that contributes to global warming.  

b) What are two changes that would increase CO2 removal from the atmosphere?  Describe what you would change, and why that would increase CO2 removal from the atmosphere. (6 pts)
Any two of:  Plant more plants- plants use CO2 in photosynthesis removing it from the atmosphere.  Increase efforts for CO2 sequestration such as storing it underground, etc.- these efforts will help reduce the greenhouse effect.

3. Ice reflects heat while soil tends to absorb heat.  One concern about melting glaciers is that exposing more soil will speed global warming.  Why? (8 pts)
Increased absorption of solar energy will further tip the balance of incoming and outgoing energy towards increased global temperatures.

4. Would the insertion of a gene into a plasmid work if the plasmid was cut with one restriction enzyme and the gene of interest was cut with a different restriction enzyme?  Why or why not? (8 pts)
No, matching sticky ends are needed for the two pieces of DNA to be connected.  Different restriction enzymes would leave different sticky ends.

5. Why has genetically modifying plants been proposed as a way to reduce contamination of the environment?  Has this advantage been realized?  Why or why not? (8 pts)
If the plants are insect, disease, stress, or herbicide resistant than spraying less chemicals should be needed.
Either:  No, the increased use of herbicide resistant plants has not changed the input of herbicides, and/or the spread of genetically modified plants by reproduction may be as dangerous as the contamination by chemicals.
Yes, using plants resistant to various stresses has meant less application of chemicals.

6. How could an animal species be changed to increase their carrying capacity?  What would be changed and how would that increase the carrying capacity? (8 pts)
The animals could be made smaller so that they would use less resources.  If each individual used less resources, then more individuals would be able to exist given the resources available.

7. What would be the larger number:  the number of animals for a sustainable existence or the number of animals for humans to derive some direct benefit?  Explain. (8 pts)
The number of animals for humans to derive some benefit would be a larger number because there would need to be enough animals for humans to use and enough for the species to remain sustainable.

8. What is one reason that the number of animals needed to maintain a sustainable population would change? (8 pts)
The resources available to that species could change, up or down, and that would change the species carrying capacity.

9. Where does the membrane of an envelope virus come from? (6 pts)
The virus takes part of the cell’s membrane as it exits the cell.

10. Exchanging body fluids with someone who is infected with HIV does not always result in passing on the HIV infection.  What would lower the risk of passing on the HIV infection even in cases where body fluids are exchanged? (8 pts)
If the infected person has very little circulating virus, if the virus is primarily in the lysogenic phase.

11. Would changing behaviors of unmarried Africans make a major change in HIV infection levels?  Why or why not? (8 pts)
Not a significant change.  Sex before marriage is less common in Africa than in the US.  Most infections are occurring during marriage.

12. How could viruses be used to genetically modify humans? (6 pts)
During the lysogenic cycle the virus injects its DNA into the host cell’s DNA, in this way the virus could insert a gene of interest in humans.

13. Is it more dangerous to set the minimum number of individuals for an animal species too high or too low?  Why? (6 pts)
Too low, too few individuals could lead to the species entering the extinction vortex.


Bonus:  How could global warming affect agricultural production?  (3 pts)
Global warming will lead to changes in climate, such as changes in rainfall, which will lead to changes in agricultural yield.