Wisconsin Fast Plants® and Product Testing

Carolina Labsheets™

In this activity, students conduct experiments to determine if a commercial product effects the germination of Wisconsin Fast Plants® seed. In doing so they practice basic science skills including collecting and graphing data, interpreting data, and doing serial dilutions

Student Lab Sheet

Needed Materials*

Wisconsin Fast Plants® Standard Seed (158805)

petri dishes, 100 × 15 mm, (741250)

filter paper (712801)

consumer products for testing

plastic bags

permanent markers

test tubes and stoppers

test tube racks

graduated cylinders or other devices for measuring 100-mL quantities

graduated dropping pipets, (736988 or similar)

beakers or cups, 200 mL

Optional Materials
Hand lenses for examining the seeds for signs of germination. Small cups for distributing seeds

Procedures

Students can work in groups of five, with each student in a group being responsible for testing a different concentration of a substance.

One 45-minute class period is needed for students to set up their experiments. Ten minutes is needed each day to count and record germinated seeds.

Purchase products for testing or have students bring them from home. Pre-approve any products for suitability and safety. Suitable products are liquids or soluble materials. Avoid testing pesticides and herbicides. Also avoid strong chemical cleaners such as those designed for cleaning ovens, removing grease from concrete, or unclogging drains. Some products may be flammable or poisonous if swallowed. Carefully read any warning labels. Vinegar is interesting to test, but leaves a persistent odor on any labware it contacts. Products that might be tested include sodas, shampoos, hand cleaners, bubble baths, dish and laundry detergents, and isopropanol (rubbing alcohol). Some interesting variations are to test regular vs. diet sodas and regular vs. antibacterial detergents.

Many consumer products are very viscous when undiluted. It may take 15 minutes or more for these products to be absorbed into filter paper. For these products, have the groups prepare the full strength plate, Plate 2, before preparing the dilutions.

Preparing Test Dilutions

Set up a workstation for each group of 5 students with the following materials:

• test tube rack with 5 test tubes and 5 stoppers
• 5 dropping pipets (fewer pipets can be used if students carefully rinse them between uses)
• test substance
• beaker or cup with water
• empty beaker

Preparing Germination Plates

This can be done in conjunction with preparing the test dilutions or during a subsequent lab period.

Set up a workstation for each group of 5 students with the following materials:

• test tube rack with dilutions
• 5 dropping pipets
• 5 filter paper circles
• 5 petri dishes
• plastic bag
• beaker or cup with water
• empty beaker

Have the students place the plastic bags with completed plates under fluorescent lights. For best germination, the lights should be about 15 to 20 cm above the plates. If you will be examining phenotypes of these seedlings for genetics, lower the lights to 5 to 8 cm above the plates. Fast Plants seeds normally germinate in 2 days. Some products may inhibit but not totally prevent germination. To allow for this, students should collect germination data on 3 or more consecutive days.

Have students look at the ingredients lists on product labels. What chemicals are listed? Students can research these chemicals on the Internet to learn more about what they are and what they do. Often, it becomes apparent why a chemical is included in a product. Students can use this information in forming a hypothesis and interpreting their results.

Optional: After germination, seedlings can be planted and grown to maturity to observe the complete Fast Plants life cycle and to check for possible detrimental effects on growth and development. Other seeds can be tested to see if they react differently to the same test substances. Radish seeds (159000) work especially well. Students can graph their data as histograms.

To incorporate more math and standardize data, students can convert their raw data into percent germination.

Answer Key to Questions Asked on the Student LabSheet

Sample Data Table

Substance Tested: Dishwashing Detergent

1. What question are you investigating?
   Will dishwashing detergent keep Fast Plants seeds from germinating?
2. Write a null hypothesis for your experiment. A null hypothesis states that changing a given variable will not affect the outcome of the experiment.
   
   If Fast Plants seeds are placed on filter paper soaked with dishwashing detergent and on filter paper soaked with water only, there will be no difference in the germination.
   
   
   1. What is the expected outcome of your experiment if the null hypothesis is correct?
      The same number of seeds will germinate on filter paper soaked with dishwashing detergent as will germinate on filter paper soaked with water.
   2. What is the expected outcome of your experiment if the null hypothesis is incorrect?
      Fewer seeds will germinate on filter paper soaked with dishwashing detergent than on filter paper soaked with water. The greater the concentration of detergent, the fewer seeds will germinate.
3. What plate represents the control group of your experiment?
   The plate containing seed on filter paper soaked with water.
4. What represents the experimental group(s)?
   The plates containing seed on filter paper soaked with dishwashing detergent.
5. What is the independent variable (sometimes called the experimental variable or manipulated variable) of your experiment?
   The concentration of dishwashing detergent used to soak the filter paper.
6. What is the dependent variable of your experiment?
   The number of seeds that germinate.
7. Did the outcome of the experiment support the null hypothesis?
   The results do not support the null hypothesis. More seeds germinated on filter paper soaked in water than on filter paper soaked in dishwashing detergent, and the more concentrated the detergent, the fewer seeds germinated.

Student Lab Sheet