Methodology of Science Writing Samples (OMSB9)

Instructions: Complete all of the tasks listed below.  There is no page limit or requirement, but your submission is estimated to be 3-4 pages (including figures).  Simply put: write as much or as little as you need to complete each task.  You should submit your assignment to the eCollege dropbox in the appropriate basket before the deadline.  Be sure to include your last name in the title of the document that you upload.  If you have any questions, including needing clarification or a helpful push in the right direction, please contact your instructor.  Good luck!

1. (Not included in this sample)

2. Consider a hypothetical study of the number of heterotrophic species in 45 different communities across the globe – 5 from each of the 9 terrestrial biomes covered in the text (pp. 386-390).  Using Data Set 1 (see note at the bottom), construct a histogram with 10 intervals.  Explain how it was constructed, including a calculation of the range of observations.  In a paragraph or two, explain what the histogram shows and discuss where communities from the different biomes are likely to be found within it.

3. Now we’ll zero in on the community that has 15 heterotrophic species.  How does this community compare to the average community?  Make comparisons using all three of the measures of central tendency – the mean, median, and mode – explaining how each measure is determined and noting any differences between them.  Name 2-3 biomes that this community is likely to come from and say why.

4. Data Set 2 (see note at the bottom) shows the results of a more detailed investigation of this community, one in which the populations (in individuals/km²) of the different species were estimated.  Describe a procedure one might have used to carry out such an investigation (i.e. in order to obtain data of that kind).  Briefly explain what would be good about the procedure you suggest as well as what problems with it you foresee. 

5. Do the best job you can of characterizing the trophic level of each of the 15 species, explaining the assignments you make.  Remember the following:

·         There are generally no more than 4 levels of consumers in a community.

·         The total population at one level will be roughly 5-20% as large as the total population one level below.

·         A species can occupy more than one trophic level simultaneously.  (Ask yourself: what would that mean for its relative population size?) 

For the purposes of this exercise, also assume the following (which are in fact quite unrealistic):

·         Most species occupy a single, unambiguous trophic level.

·         Each species at a given trophic level is equally common (i.e. its population size is similar to other species at that level).

6. Make a circle graph showing the relative abundance in this community of organisms categorized by trophic level.  Your graph should encompass all 15 species, so include hybrid categories (e.g. primary/secondary consumer) if you found them useful/necessary.

7. Explain the concept of a keystone species.  Describe how one might conduct an experiment (or series of experiments) to test whether one of the 15 species in this community is a keystone species.  What sort of data would one look for?  And if there is a keystone species, what could account for its playing that role?  (Feel free to discuss specific examples of keystone species here if you like).     

8. (Not included in this sample)

Writing Assignment #4

Instructions: Complete all of the tasks listed below.  There is no page limit or requirement, but your submission is estimated to be 3-5 pages.  Simply put: write as much or as little as you need to complete each task.  You should submit your assignment to the eCollege dropbox in the appropriate basket before the deadline.  Be sure to include your last name in the title of the document that you upload.  If you have any questions, including needing clarification or a helpful push in the right direction, please contact your instructor.  Good luck!

Part I:  Chemistry of the Carbon Cycle

Use the chemistry terms we have learned this semester to give a richer, more informative explanation of the carbon cycle than we were able to give last semester. Some topics to include:

• The chemical basics of the primary form of atmospheric carbon
• The major carbon-containing molecules in the biotic reservoir of the cycle
• Where in the carbon cycle one would primarily expect the occurrence of dehydration reactions and hydrolysis reactions, respectively
• The connection between carbon in the biotic reservoir and carbon found in fossil fuels

Important notes:

(i)     One of your main goals in this section should be brevity – aim to explain things as efficiently as possible, focusing on the major points and leaving out unnecessary details

(ii)   You should explain things at a level appropriate for this class – that is, if you know a lot more about chemical bonding/reactions, leave that information out! If you have studied certain organic molecules (or reactions involving them) in detail elsewhere, leave that information out!

(iii) A simple way to think of this: your goal is to write a helpful explanation for fellow students in this class who are, say, preparing for an exam on the current material.

Part II:  Membranes

(A) Describe the chemical structure of a phospholipid and explain how that helps to account for the structure and function of cell membranes.

(B) A researcher hypothesizes that cell membranes are permeable to a certain substance X, i.e. that X can pass freely through such membranes.  If this were true, the concentration of X inside and outside cells would be expected to be roughly equivalent.  To test this hypothesis, the researcher has taken a very large number of readings of extracellular fluid (the fluid outside of cells), measuring the concentration of X.  The researcher has analyzed the results and determined that the data is normally distributed with a mean of 1.66 mg/dL and a standard deviation of 0.12 mg/dL.  Now the researcher has begun to take readings of intracellular fluid (the fluid within cells), measuring the concentration of X, and so far has gotten the following results (in mg/dL):

1.26, 1.33, 1.37, 1.42, 1.62, 1.75

·         First, what characteristics would the data concerning extracellular concentration have to exhibit to justify the conclusion that it is normally distributed?

·         Second, while the researcher’s hypothesis suggests that extracellular and intracellular fluid can be considered a single statistical population, are any of these 6 intracellular observations unlikely (or highly unlikely) to have come from the same general population as the extracellular readings?  In other words, for each of the 6 intracellular observations listed, determine whether it is statistically significant.  Explain your judgment, including any necessary calculations. (And be sure to note whether you used a one-tailed or two-tailed test and why).

·         Third, would your assessment of statistical significance change for any of these observations if the extracellular data had come from a sample of 25 observations rather than from a much larger sample?  Why or why not?

·         Fourth, based just on the intracellular results so far – admittedly too small a sample! – what seems to be going on with cell membranes and substance X?

Good luck!

Writing Assignment #5

Instructions: Complete all of the tasks listed below.  There is no page limit or requirement, but your submission is estimated to be 3-5 pages.  Simply put: write as much or as little as you need to complete each task.  You should submit your assignment to the eCollege dropbox in the appropriate basket before the deadline.  Be sure to include your last name in the title of the document that you upload.  If you have any questions, including needing clarification or a helpful push in the right direction, please contact your instructor.  Good luck!

Part 1: Glycogen Levels in Animal Tissues

The following is a description of an experiment conducted to study the glycogen levels of 5 tissues, arbitrarily labeled as tissues A, B, C, D, and E. 

INTRODUCTION

Glycogen is the major long-term energy storage molecule in animals. Begin your response by describing the structure of glycogen and explaining how the energy stored within it is accessed and put into usable form by the cell.

METHODS
10 rhesus monkeys were imported from India and quarantined for 90 days before they were used for experiments. The monkeys were 2 to 4 years old and were fed a commercial stock diet while at MSB Laboratories.  The modification of the Failor-Hoshi method was used to assay the glycogen content of the five tissues, A, B, C, D, and E.

RESULTS
The glycogen concentrations (in milligrams of glycogen per gram wet weight) for the 5 tissues of the monkeys are presented in the following table:
 

DATA ANALYSIS
(i) Estimate the mean glycogen concentration for each tissue with a 95% confidence interval. Carefully explain (a) the general significance of a confidence interval and the reasoning behind how it is calculated (i.e. why it has the particular formula it does), and (b) how you found the confidence interval in these cases, providing at least one sample calculation.

(ii) Estimate the difference between the means of tissue A and tissue B, again with a 95% confidence interval.

CONCLUSION

Draw conclusions from this data, including an identification of the two tissues in which glycogen is highly enriched.  Why might glycogen be enriched in these tissues?  (Feel free to do a little research to help you with this section; there is no need to cite sources as long as you put things in your own words).

Part 2: Amino Acid Composition of Proteins

First, explain in a paragraph how the ultimate structure of a protein depends on its amino acid sequence.

(The remainder of this assignment is not included in this sample).