A. Graphs, Tables, and Calculations
i. Produce one bar graph showing the mean total phosphorus concentration (μg/L) in each flask. Use two different styles to differentiate between initial and final samplings. Pair the initial and final measurements for each flask side-by-side to ease your comparisons. Add error bars equal to ± the standard deviation.
ii. Produce one bar graph showing the mean phosphate concentration (μg/L) in each flask. Use two different styles to differentiate between initial and final samplings.
Pair the initial and final measurements for each flask side-by-side to ease your comparisons. Add error bars equal to ± the standard deviation.
1.State your hypothesis(es). Do the data support or reject your hypothesis(es)?
2.Explain what is meant by the phrase “phosphorus can be too much of a good thing.”
What are beneficial properties of phosphorus in aquatic environments? What are negative properties of phosphorus when it is excess in an aquatic environment?
3.List three components of a good experimental design. Next to each one, describe what we did (be specific) in Lab 3 to exemplify it.
Note: things like “posing a question,” “testing a hypothesis,” “following a procedure,” and “being careful” are not what I’m looking for here, as these are basic to any study. Think about our class discussions and more substantial concepts we talked about.
4.Based on your graphs, which treatments experienced changes in total phosphorus
and phosphate concentrations that are likely to be of scientific interest?
How can you tell, given inherent measurement error(uncertainty) surrounding the treatment means? Based on your knowledge of the phosphorus cycle and the organisms in your treatments (or not!), explain all the key changes that occurred.
5.Define measurement error. Why is it a part of any scientific study, no matter how “careful” you are as a scientist? Discuss two likely, specific sources of measurement error for this experiment that could account for the variation in treatment means you calculated. I’m not looking for things like “my lab partner didn’t follow the procedure correctly.” I want more substantiative answers here: you’re dealing with lots of replicated data: pretend you personally collected it all yourself.
6.Calculate the mean amount of particulate phosphorus(μg/L) at the end of the experiment in the algae only treatment. Where is this phosphorus located?
Where do you think this phosphorus was located at the beginning of the experiment, and what form was it in then?
Explain how you arrived at your answer and report the result. Hint: set up a new column in the Excel spreadsheet containing the raw data from the experiment. Use Excel to compute your answer quickly.
7.How would evaporation of water out of the treatment flasks during the week-long experiment, if unaccounted for, affect measurement of both total phosphorus concentration (μg/L) and the total mass (μg) of phosphorus in a flask? Note these are not the same thing!
8.Looking at the total phosphorus results in the algae + Daphnia treatment, are we violating the law of physics that states that matter (elements) cannot be created or destroyed? Why or why not? Hint: Think about what is being collected (or not) when you take your total phosphorus water sample from the flask.
C. Style, Clarity, and Mechanics
1. Complete heading provided
2.Length is appropriate; questions are answered concisely
3.No distracting punctuation, spelling errors, grammar, or mechanics (assignment
reads clearly and smoothly)
4.Graphs/tables are legible and thoughtfully displayed, with descriptive titles and proper labels with units
Phosphorus Concentration In Aquatic Environments
Length: 4 pages (1103 Words)
Part B: Questions
The first set of the hypotheses was based on the mean total phosphorus concentration (μg/L) in the flasks. The null and alternative hypotheses were framed as follows:
Null hypothesis: The initial and final measurements for the mean total phosphorus concentration (μg/L) were not significantly different in each flask.
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