Dr. Reichler’s Bio 301L   MWF 11am-noon    Print Name:______KEY_________________
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? (6 pts)
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 together.

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 CO2.
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 Antagonistic Selection.

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 lived longer.

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.