How did oxygen generation by Elodea vary in dark and light conditions?

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

specific details

__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 clarity

Data accuracy

___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)



Scientific language

Data addressed


___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

support conclusions.

___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.

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