How did oxygen generation by Elodea vary in dark and light conditions?
This assignment requires you to evaluate a hypothesis and communicate the results of your
experiment O2 generation by Elodea under different conditions. The questions below are meant to
guide you to reporting the key findings of your experiment and help you think through how to
explain the findings and draw conclusions from them in a scientific manner. Because you’ve
already had an opportunity to practice these skills once, this assignment is worth 16 points.
ASSIGNMENT: Please respond to the following questions to complete your laboratory write up. For this
assignment you will only focus on O2 generation experiment. Make sure that your write up is accurate, and
clearly written so that it is easily readable.
A grading rubric is provided on the second page of this assignment. To earn full points on your write up,
you must provide answers that align to the “meets” column of your grading rubric as well as meeting all
“Quality of Writing and Mechanics” elements described in the rubric. There are also some tips on pages 3-4
of this assignment to help you succeed.
• Type your responses, using 1.5 or double spacing.
• Include the section headings (Hypothesis, Results, Analysis) and question number (example: 1, 2, 3,
etc) in your answers but do not rewrite the question.
• Graphs may be made with a computer program (example: Microsoft excel, Mac numbers, etc) or may
be neatly produced with a ruler on graphing paper.
• Print out the cover sheet on page 2 of this assignment, read and sign the academic honesty statement,
and submit it with your write up. Your instructor WILL NOT accept a write up without the signed cover
DUE DATE: Your write up is due at the beginning of class next week. Late assignments will have 1 point
deducted per day up to 5 days, at which point the assignment will be assigned 0 points.
Hypothesis and Prediction – Part 1 of Rubric
1. What did you think was going to happen in this experiment and why? You may find it helpful to state your
answers to these questions as an “if-then” hypothesis-prediction. Be sure you have included a biological
rationale that explains WHY you made this hypothesis/prediction. Think about what is required for and
what is produced by the process of photosynthesis.
Results – Part 2 of Rubric
2. How much O2 was generated by Elodea in dark and in light conditions? Answer this question by creating
a bar graph that shows the results of your experiment. If you need assistance building a graph, there is a
Guide to Graphing resource available on your Moodle lab course site.
Analysis- Part 3 of Rubric
3. Explain why you think that the results shown in your graph support or refute your hypothesis (remember
we never “prove” anything in science). Consider all your data and the overall data pattern as you answer
this question. Don’t ignore unusual data that may not seem to fit into a specific patterns (“outliers”).
Explain what you think might be behind these unusual data points.
4. What is the biological significance of your results? What biological concepts explain completely why these
events happened in the experiment? How do these results help you understand the process of
photosynthesis? Think about giving a specific example.
References- Mechanics Checklist
5. Provide at least one full citation (make sure you include an in-text citation that pinpoints where you used
this resource) for a resource you made use of in performing the experiment, understanding the concepts
and writing this assignment. (Perhaps your lab manual? Your textbook? A website?) If you used more
than one resource, you need to cite each one! If you need help with citations, a Guide to Citing References
is available on your Moodle lab course site.
Please print out and submit this cover sheet with your lab writeup!
Lab Writeup Assignment (1) Assessment Rubric- 16 points total Name: ________________________________________
Element Misses (1 point) Approaches (3 points) Meets (5 points)
___Hypothesis is unclear and hardto-understand
___Hypothesis is not testable
___No biological rationale for
hypothesis or rationale is fully
___Hypothesis included is clearly
stated, but not specific or lacks
__Hypothesis is testable, but not in a
feasible way in this lab
___Some foundation for hypothesis,
but based in part on biological
___Hypothesis included is clearly
stated and very specific
___Hypothesis is testable and could
be tested within lab parameters
___Rationale for hypothesis is
grounded in accurate biological
___Graph lacks a title
___Axes are not labeled
___Variables not addressed in graph
___No key or way to tell data points
___Graph is hard to read and
comparisons cannot be made:
Inappropriate graph type or use of
___Data graphed is inaccurate or
does not relate to experiment
___Graph has a title that is not very
___Axes are either unlabeled, or
units are unclear or wrong
___Variables addressed in graph, but
not on correct axes
___Key included, but is hard to
___Graph is somewhat readable,
comparisons can be made with
difficulty: Appropriate graph type, but
not scaled well
___Data graphed is partially
accurate; some data is missing
___Graph has a concise, descriptive
___Axes are labeled, including
clarification of units used
___Variables on correct axes
___A clear, easy-to-use key to data
points is included
___Graph is clearly readable and
comparisons between treatments are
easy to make: Graph type and scale
are appropriate to data
___Data graphed is accurate and
includes all relevant data, including
controls (if needed)
___Hypothesis is not addressed
___Hypothesis is described using
language like proven, true, or right
___No explanations for data patterns
observed in graph or data does not
___No biological explanation for data
trends or explanations are completely
___Hypothesis is mentioned, but not
linked well to data
___Hypothesis is not consistently
described as supported or refuted
___Some data considered in
conclusions but other data is ignored.