Dr. Reichler’s Bio 301M MWF 9-10am Print
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
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
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
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
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