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:
- 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
- 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!
- 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 structureand 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?