AP LAB 12 WRITE-UP GUIDELINES

Due Fri, 4/8 orThurs, 4/7by 5 for 5!

Title

I. Introduction

  • Explanation of the importance of oxygen availability to aquatic ecosystems including reasons it’s often a limiting factor
  • Purpose & Hypothesis for Part A, including justification for your hypothesis
  • Purpose & Hypothesis for Part B, including justification for your hypothesis

II. Materials & Methods

  • Description of procedure followed in Parts A, B
  • Specific procedure available on my web page
  • For a complete . . .

III. Data

  • Part A

Construct a data table for individual data with columns for Temperature, DO, % Saturation

Construct similar data table showing averages for Class Data

Construct a graph using Class Data

  • Part B

Construct a data table showing DO reading for Initial & Dark BOD bottle set-ups

Show the calculation for Loss of Oxygen Due to Respiration

Re-construct data table at the bottom of page 141 showing Table Data with number of rows corresponding to # of L bottles set-up

Re-construct data table on page 142 for Class Data

Construct graph showing Net vs Gross Productivity using Class Data

IV. Questions

  • Answer the following in complete sentences . . . you do not need to re-write the question, but it should be re- stated in your answer.
  • Refer to the line on your graph that represents Net Productivity. Provide an explanation for its direction and slope, including the point at which the rate of respiration equals the rate of photosynthesis.
  • Explain the difference between gross and net productivity, including how they were calculated in this lab.
  • Two researchers, one at Toolik Field Station in northern Alaska and the other at LaSelva Biological Station in Costa Rica, are studying populations of aquatic arthropods in freshwater pools during July. The researcher in Alaska determines an average of 280 arthropods per m3 of water in the pools she is studying. The researcher in Costa Rica determines an average of 125 arthropods per m3 at his study site. In terms of the current lab, what are two factors that account for this difference? Explain.
  • Describe at least three important general characteristics of arthropods, including the evolutionary importance of each.
  • Discuss how (a) wind and (b) altitude affect DO concentration.
  • Explain the principle of the Winkler method in determining dissolved oxygen concentration. Please note: You do not need to include all of the chemistry behind this method . . . just an overview of the steps involved.
  • Eutrophication is created by large run-offs of nitrogen and phosphorus into an aquatic ecosystem. Although it can occur naturally, it is typically a man-made problem and it is the reason detergents high in phosphates were banned years ago. The enriched concentrations of N and P stimulate a) algal blooms, leading to b) explosions in bacterial populations, followed by c) decreases in populations of larger aquatic plants and fishes. Explain this 3-part sequence of events . . . why does each event occur?
  • Although there are negative consequences when too much N and P are available, they can also be limiting factors in a community. Describe why all organisms need these two minerals and how they are naturally recycled in an ecosystem.

V. Conclusion

  • Re-address purpose for Part A, B . . . in other words, did we accomplish our purpose?
  • Were your hypotheses supported or refuted according to your data and/orclass data?
  • Error Analysis