CHAPTER 13 INVESTIGATION: DESIGN YOUR OWN PLANT EXPERIMENT
*Abiotic Factors and Plant Growth*
Many factors affect plant growth. Is it possible to test some in a laboratory setting? In this investigation you
will choose an abiotic factor and attempt to test how (or if) it affects the growth of radish seedlings. You
will also determine if pH levels have an effect on duckweed.
*PROBLEM*
How do abiotic factors affect plant growth?
*MATERIALS*
* radish seedlings and
* labels
* marker
* water
* 4 cups
* ruler
* potting soil
* abiotic factors to test (you pick)
* Any materials you may need for YOUR experiment
*PROCESS SKILLS*
* Designing Experiments
* Collecting Data
*Procedure - Part 1 - Abiotic Factors and Radish Seeds*
1. Choose an abiotic factor to test on the growth of radish seedlings. Possible factors include amount of
sunlight, amount of water, soil type, light color available to plants, or solution added to soil.
2. Determine a way to vary the factor you have chosen. Be sure to include at least three different
settings of your variable and to keep all other factors constant. Don't forget to have one of your
plants be a "control" to compare to. Write out the abiotic factor you are testing, and a procedure for
your investigation.
Abiotic factor:
Procedure:
3. Obtain 4 cups, soil, and 4 radish seeds. Label one cup "Control" and the remaining three "A," "B",
and "C", or list the abiotic factor that is different in each cup. Remember what each cup contains.
4. Each day make an observation of your plants. Mention whether the seed has germinated, height of
plant (in cm), color, and number of leaves present.
5. Continue the measurements for a period of 8 class days. Use the same method to repeat
measurements each day. Be sure to keep plants watered with exact amount if needed.
6. Record all data you generate in the a well-organized data table. Copy the chart below 4 times, one
for each plant.
Plant: ________
Day 1 - _________
Day 2 - _________
Day 3 - _________
Day 4 - _________
Day 5 - _________
Day 6 - _________
Day 7 - _________
Day 8 - _________
Germinated (Yes/No)
Color
Height (cm)
# of Leaves
*Analyze and Conclude - Answer on your paper*
1. Identify Variables: What are your independent and dependent variables in Part 1? What are your
constants? What is your control?
2. Operational Definitions: On the basis of your procedure, what dependent variable do you think will
be the most reliable to monitor plant progress in Part 1? Why?
3. Graph Data: Make a line graph to present the data you obtained on plant growth in Part 1. Attach it
to your paper. The X-axis should be Day, and the Y-axis should be height in cm. Make a line for
ALL four plants. What trend do you notice in your graph? Make sure your scale is correct.
4. Conclude: By studying your data in Part 1, what can you conclude about how (or if) your variable
affects the growth of radish seedlings?
5. Experimental Design: What possible sources of error may have occurred in Procedure 1? Why
might they have occurred?
6. Extension: How would you design an experiment to determine whether a specific biotic factor
influences plant growth?