Lettuce Seed Dose/Response
Bioassay
Data Form
Name __________________________
Date __________________________
Chemical tested ___________________________
100% concentration _____________________ mg/L
Length of experiment _____________________ days
Constants (such as temperature and light)
______________________________________
Table 2a.
Seed Germination Data
|
Concentration (%) |
Concentration (mg/L) |
# Seeds
Germinated/Dish |
Average # Seeds
Germinated |
||
|
Control |
|
|
|
|
|
|
0.001% |
|
|
|
|
|
|
0.01% |
|
|
|
|
|
|
0.1% |
|
|
|
|
|
|
1% |
|
|
|
|
|
|
10% |
|
|
|
|
|
|
100% |
|
|
|
|
|
Table
2b. Radicle Length Data
|
Concentration (%) |
Radicle Length(mm) |
Average Length
(mm) |
||||||||||||||
|
Control |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
0.001% |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
0.01% |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
0.1% |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
1% |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
10% |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
100% |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Make bar
graphs of the averages you calculated in Tables 1a and 1b:
Name __________________________
Some
questions to consider: (Please answer using full sentences.)
1. Did at least 80% of the seeds in the control
dishes germinate? If not, what would
you recommend doing differently next time to try to get a better germination
rate?
2. Did lettuce seed germination respond in a predictable way to
concentration? Describe any trends you
observed.
3. Do any of your data not fit the trends you observed? If so, can you think of any reasons why these data might lie outside the range you would expect?
4. What is your estimate of the TC50 based on your lettuce seed germination data?
TC50 = ___
What is your estimate of the TC50 based on your radicle length data?
TC50 = ___
Which shows a greater response to the chemical you tested:
germination rate or radicle length?
Describe any similarities or differences that you noticed in trends
between these two indicators of toxicity.
5. What can you conclude about the toxicity of
the substance you tested? Is this what you expected? Was your hypothesis
supported by the data?
6. If other students carried out a dose/response
experiment using the same chemical, did their data follow the same trends as
yours?
7. Based on this experiment, would you say that
lettuce seed germination or root length would provide a useful bioassay for
water samples from the environment? Why or why not?
8. If you were going to repeat this experiment, what would you do differently? How might you improve the experimental design to reduce the variability of your data or lead to more reliable results?
© NSTA. Cornell Scientific Inquiry
Series. For use with Assessing Toxic Risk, Protocol 2.