Identifying the Environmental Culprit Harming Amphibians

(http://www.mhhe.com/biosci/genbio/tlw3/virtual_labs/lab31/labs/lab31/home.html).
Please read "Explore the Issue Being Investigated" and "Gain an Overview of the Experiment". You will also need to read the original research paper to answer some of the questions, but it is short and easy to read. Then run the virtual experiment exploring the original paper looking at the relationship between UV-B light and amphibian survival. Do all the steps, reading all the parts carefully. You will need to know the information to answer the questions. Fill in the answers to the lab report as you do the experiment. When you get to the end (step 6), click on the Deformities button at the bottom of the page to carry out another experiment on the effect of UV-B on amphibian deformities. At the end of that one, click on the ‘run a related experiment’ button at the bottom of the page to look at the effect of DNA repair enzymes on UV-B damage to amphibians. You must have results from 3 different experiments to get full points for this lab.
Please use complete sentences and proper grammar and spelling throughout your lab report. Answer questions thoroughly and completely to get full credit.
Experiment 1: Does UV-B radiation cause deformities or decreased survival in amphibians?
I. Hypothesis
State your hypothesis (copied from the lab)

II. Results

1. Provide a screen shot of the graph showing the analyzed data both with and without the UV-B shield. Crop down to just the graph and enlarge it.
2. In your own words, describe this data, including numbers (i.e., what the survival rate was after a certain number of days). Do not provide any interpretation, just summarize the important trends in the data (do not list every data point, those can be seen from the graph). Describe how the survival of UV-B shielded and UV-B unshielded eggs and larvae change over time, including the final survival rates at the end of the experiment. Be thorough and specific. Several sentences are required for a good answer.
3. At what point in time do you begin to see a difference between the two treatments?
4. At what point in time would you say that the difference in the two treatments becomes significant?

III. Conclusions
In part 5 of the virtual lab, called Drawing Conclusions, you are given 4 statements that are possible conclusions for this part of the experiment. Explain, referring back to the data, why you DID or DID NOT select each of the 4 statements as conclusions. Use actual data, i.e., numbers of days or percentages of surviving animals, as appropriate. Some answers come from the introductory material and original paper.

1. The survival rates of the animals exposed to UV-B radiation were affected immediately upon exposure to UV-B radiation.
2. The shielding of UV-B radiation allowed a large majority of eggs to develop and survive the duration of the experiment.
3. The mylar shield was 100% effective in blocking all UV-B radiation.
4. UV-B radiation had dramatic effects on reducing the survival rates of the UV-B unshielded animals.

IV. Questions
Please answer the following questions concerning this experiment.

1. Experiments performed in the lab showed an effect of UV-B irradiation on survival rates, why was it important to show that the same results occur in field experiments?
2. The animals used in this experiment routinely lay their eggs in open shallow water. Do you think they would experience similar problems of decreased survival rates if they laid their eggs under rock shelves that line the edges of the lake?
3. What were the independent and dependent variables in this experiment?
4. What is the function of the mylar shield in this experiment? What is the function of the acetate shield? Explain which is the experimental treatment and which is the control and why the control is needed. Make your answer specific to this experiment, not just a general statement about the function of controls.
5. Do your results support or reject your hypothesis? Explain

Experiment 2: Does UV radiation cause deformities or decreased survival in amphibians?
I. Hypothesis
Re-state the hypothesis from the first experiment.

II. Results

1. Provide a screen shot of the graph showing the analyzed data both with and without the UV-B shield. Crop down to just the graph and enlarge it.
2. In your own words, describe this data, including numbers (i.e., percentages and number of days). Do not provide any interpretation, just summarize the important trends in the data (do not list every data point, those can be seen from the graph). Describe how the number of UV-B shielded and UV-B unshielded animals with deformities changes over time, including the beginning and end points.
3. For how many days did the shielded and unshielded animals show approximately the same number of deformities?
4. From days 6-14 was the rate of increase in deformities in the unshielded eggs constant or accelerating over time? Base your answer on the analysis line. (Note that a straight line shows a constant rate of increase and a J-shaped line shows an accelerating rate of increase.)

III. Conclusions
In part 5 of the virtual lab, called Drawing Conclusions, you are given 4 statements that are possible conclusions for this part of the experiment. Explain, referring back to the data, why you DID or DID NOT select each of the 4 statements as conclusions. Use actual data, i.e., numbers of days or percentages of surviving animals, as appropriate. Some answers come from the introductory material and original paper.

1. UV-B radiation had no significant effect on the occurrence of developmental deformities in the animals.
2. Developmental deformities were uncommon in the UV-B shielded animals.
3. Decreasing the exposure of the eggs to UV-B radiation significantly reduces the occurrence of developmental deformities.
4. Differences in temperature contributed to the occurrence of developmental deformities in the UV- B unshielded animals.

IV. Questions
Please answer the following questions concerning this experiment.

1. What is the importance of the relationship between UV-B radiation and deformities in developing salamander embryos?
2. Not all amphibian species are affected by UV-B radiation. Can you think of biological or environmental measures that might be exhibited in these non-UV-B sensitive amphibian species that confers protection on them from UV-B radiation?
3. Do your results support or reject your hypothesis? Explain

Experiment 3: Do DNA Repair Enzymes Protect Amphibians from UV-B Damage?
I. Hypothesis
State the hypothesis for this experiment (copied from the lab but different than the first two)

II. Results

1. Provide a screen shot of the graph showing the analyzed data both with and without the UV-B shield. Crop down to just the graph and enlarge it.
2. In your own words, describe this data. Do not provide any interpretation, just summarize the important trends. Describe the relationship between increasing photolyase activity and survival rates for shielded and unshielded animals, including the starting and ending points.
3. Which level of photolyase had the greatest difference between shielded and unshielded animals? Which had the lowest difference?
4. Which line showed a greater slope, indicating a greater effect of increasing photolyase on survival rate? III. Conclusions
   In part 5 of the virtual lab, called Drawing Conclusions, you are given 4 statements that are possible conclusions for this part of the experiment. Explain, referring back to the data, why you DID or DID NOT select each of the 4 statements as conclusions. Use actual data, i.e., numbers of days or percentages of surviving animals, as appropriate.
5. Animals with lower levels of photolyase activity had lower survival rates when exposed to UV-B radiation.
6. Species with low photolyase activity had just as low survival rates whether shielded or not shielded from UV-B.
7. The level of photolyase activity had no effect on animals that were unshielded.
8. There is a general positive correlation between the levels of photolyase activity and protection from UV-B radiation.

IV. Questions
Please answer the following questions concerning this experiment.

1. For some species with very high photolyase activity there was no effect on survival rates whether there was or was not a UV-B shield. Why do you think this is the case?
2. Based on these results, would you expect any species that has a low level of photolyase activity to be at risk from UV-B radiation exposure?
3. Some species with low photolyase activity in fact are not subject to damage by UV-B radiation in their normal environment. Can you explain why this might be the case?
4. Why do you think that the amount of photolyase was more important to the survival of unshielded animals than shielded animals?
5. Do your results support or reject your hypothesis? Explain.