Dr. Reichler’s Bio 301L MWF 11am-noon
Exam #3 May 2, 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. What was unusual about finding tools along with the bones of H.
florensiensis? (6 pts)
They have relatively small brains but
the tools indicate higher brain function.
2. When would a rod (the neurons that perceive light in human eyes) use
more energy (ATP), when there is light or darkness? Why? (8 pts)
In light. This is when the rod
is polar, and pumps are needed to pump positive ions out of the cell.
3. What would be the effect if none of your neurons were
interconnected? (6 pts)
There could be no decision
making. Every input would lead to only one response.
4. What information about the function of dreams was gained by
monitoring the parts of the brain that are activated during dreaming?
Dreams activate some of the same
areas that are activated when we are awake. This makes it
improbable that dreams are random.
5. Why is calcium critical for proper muscle movement? (8 pts)
Tropomyosin moves away from actin
when calcium is present allowing myosin to pull the actin filaments
6. Complex carbohydrates (sugars) are primarily composed of carbon
molecules that are eventually released as CO2. Two different
processes are involved that take place in two different places.
Where do each of these processes take place, and what part of the
process is occurring in each place? (8 pts)
Animals- chemical digestion in mouth
and/or in small intestine breaks complex carbs to simple carbs that are
then used in the mitochondria for cellular respiration and released as
Plants- carbs are produced in
chloroplasts by photosynthesis and then broken down in the mitochondria
during cellular respiration.
7. If the pumps that move H+ across the mitochondrial membrane stopped,
how quickly would ATP production stop (immediately or after a little
while)? Why? (8 pts)
ATP synthesis can continue as long as
the gradient of H+ exists. It will take a little while for the
gradient to equalize and stop ATP synthesis.
8. If the genes leading to homosexuality are the same for male and
female homosexuality, can Sexually Antagonistic Selection explain the
inheritance of these genes? Why or why not? (8 pts)
Yes. Sexually Antagonistic
Selection says that the genes for homosexuality would reduce
reproduction in one sex and increase it in another. One gene that
had a different effect in the two sexes would be explained by Sexually
9. How did mutating a gene in flies demonstrate a connection between
the nervous system and lifespan? (8 pts)
Flies that lacked a sense of smell
10. Is physical digestion harder for carnivores or herbivores?
Why? (6 pts)
Herbivores need to break down the
hard cellulose cell wall to get to the nutrients which is harder than
breaking down the proteins and soft tissue of an animal.
11. Plants don’t have muscles. At the cellular level, what is one
difference between movement in animals and plants? (6 pts)
Any one of: Plant movement
often involves growth instead of cells moving. Plants move by
moving water, animals by contracting cells. Plants don’t use
actin, myosin, or tropomyosin for movement.
12. What would you do to a plant if you wanted to starve it to death,
and why would it starve? (6 pts)
Put it in darkness or with a lack of
CO2. It needs light and CO2 to do photosynthesis and make sugars,
its food source.
13. What are two different signals that plants communicate with other
organisms? (8 pts)
Any two of: The plant is being
eaten is communicated to other plants via jasmonic acid or to
wasps. Plants over other plants communicate their presence by the
far-red light that gets through.
14. 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)
Either: Yes, by making plants
resistant to stresses such as insect attack etc, less chemicals need to
be added. No, herbicide resistant plants do not decrease
herbicide use, and these are the most common GM crops.
Bonus: What is one hypothesis about why students born at
different times of the year might score differently on exams, and what
is one experiment that could disprove this hypothesis? (3 pts)
Any one of: Younger students do
poorly; hold some students back and see if they do better. Day
length makes a difference; do similar experiment in southern
hemisphere. Food availability is having an affect; give
mothers/toddlers vitamins and see what happens.