How to soak lettuce seeds

Experiment 2: The Effect Of Air Pollution On Seed Germination

Experiment 2: The Effect of Air Pollution on Seed Germination

The objective for this experiment is to find out how ammonia fumes affect lettuce seed germination. This will be tested by adding an ammonia-soaked cotton ball to a resealable bag with lettuce seeds for one week and comparing the resulting germination rate to the rate of lettuce seeds in a separate resealable bag with a water-soaked cotton ball.

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Materials

6 mL Ammonia, NH3 (1) 100 mL Beaker 2 Cotton Balls (1) 10 mL Graduated Cylinder 50 Lettuce Seeds Permanent Marker (1) 9 cm Petri Dish Pipette

(2) 8 in. x 12 in. Resealable Bags 2 Weigh Boats *2 Paper Towels *Scissors *Water, H2O *You Must Provide

Procedure

1. Use the permanent marker to label two resealable bags as “Control” and “Ammonia”.

2. Then, use the permanent marker to trace the outline of the Petri dish on the paper towels two times (you should create two separate circles).

3. You will use the top and bottom halves of the Petri dish to create two germinating dishes. Cut each circle from the paper towel so that each will fit inside the top and bottom half of a Petri dish.

4. Fill the 100 mL beaker with approximately 20 mL of water. Then, use this water to fill a pipette, and use the pipette to saturate the paper towel circles in the Petri dish halves.

5. Disperse 25 lettuce seeds evenly across each wet paper towel circle.

6. Use the 10 mL graduated cylinder to measure and pour 6 mL of water into a weigh boat. Place a cotton ball into the boat and let it absorb all of the liquid.

7. Place the weigh boat and one of the Petri dish halves with the seeds in it inside the “Control” resealable bag. Snap the seal to ensure the environment is contained within the bag.

8. Use the 10 mL graduated cylinder to measure and pour 6 mL of ammonia into the second weigh boat. Place a cotton ball into the boat and let it absorb all of the liquid.

9. Place the weigh boat and one of the Petri dish halves with the seeds in it inside the “Ammonia” resealable bag. Snap the seal to ensure the environment is contained within the bag.

10. Carefully move both bags to a sunny windowsill, and leave for 5 - 7 days.

11. Record your observations in Table 4 after 5 - 7 days have passed.

Table 4: Effects of Ammonia of Seed Germination

Sample

Number of Seeds Germinated

Percent Germination (%)

Control

Ammonia

Post-Lab Questions

1. How did the ammonia influence the seed germination? Explain your answer using results from the experiment.

2. Why is it important to have a cotton ball soaked in water in a bag with the seeds as part of this experiment?

3. Why were the plants in this experiment unable to tolerate the air pollution? Propose a way to treat the air pollution in this experiment in order to create a tolerable living environment. Additional research may help you answer this question.

4. What components of an ecosystem could be affected by air pollution? Explain why.