Lab: Writing Assignment
How does ethylene affect ripening of fruit?
This assignment requires you to evaluate a hypothesis and communicate the results of your study on the production and effects of ethylene on ripening of fruit. 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.
ASSIGNMENT: Please respond to the following questions to complete your laboratory write up. For this assignment you will only focus on the plant ripening data. 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 below. 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: 12, 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 sheet.
Hypothesis and Prediction – Part 1
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 how ethylene is produced and how the exposure to ethylene affects the ripening of fruit.
Results – Part 2
2. How did the treatment to which you exposed your fruit affect the firmness of the fruit as measured by the penetrometer over the three weeks that you collected data? Answer this question by creating a bar graph for the data in Table 4 (Note: only graph difference between baseline and post-treatment average!). If you need assistance building a graph, there is a Guide to Graphing resource available on your Moodle lab course site.
Analysis- Part 3
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 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 how hormones affect plants? 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.
Graph: The graph is a visual representation of the data you gathered while testing your hypothesis. Remember that:
• A graph needs a concise title that clearly describes the data that it is showing.
• Data must be put on the correct axes of the graph. In general, the data you collected (representing what you are trying to find out about) goes on the vertical (Y) axis. The supporting data that that describes how, when or under what conditions you collected your data goes on the horizontal (X) axis. (For this reason time nearly always goes on the X-axis).
• Axes must be labeled, including the units in which data were recorded
• Data points should be clearly marked and identified; a key is helpful if more than one group of data is included in the graph.
• The scale of a graph is important. It should be consistent (there should be no change in the units or increments on a single axis) and appropriate to the data you collected
Analysis: You need to evaluate your hypothesis based on the data patterns shown by your graph. Remember that:
• You use data to determine support or refute your hypothesis. It is only possible to support a hypothesis, not to “prove” one (that would require testing every possible permutation and combination of factors). Your evaluation of your hypothesis should not be contradicted by the pattern shown by your data.
• Refer back to the prediction you made as part of your hypothesis and use your data to justify your decision to support or refute your hypothesis.
• In the “if” part of your hypothesis you should have provided a rationale, or explanation for the prediction you made in your hypothesis (“then” part of hypothesis”). Use this to help you explain why you think you observed the specific pattern of data revealed in your graph.
• You should consider all of the data you collected in examining the support (or lack of support for your hypothesis). If there are unusual data points or “outliers” that don’t seem to fit the general pattern in your graph, explain what you think those mean.