Biology 112
The Effects of Acid Rain on Seed Germination
Name: ______________________________ Date: _______________
Background Information:
When fossil fuels and metal ores containing sulfur undergo combustion (burning), the sulfur is
released in the form of a poisonous gas called sulfur dioxide which then enters the
atmosphere. Another dangerous gas called nitrogen oxide gets released into the atmosphere
by combustion of fossil fuels in vehicles and power plants. It also gets released by fertilizers
used on farms. These poisonous gases combine with water droplets in the atmosphere and fall
as acid rain. Acid rain can be up to 40 times more acidic than normal rain. Years ago, scientists
hypothesized that the presence of acid rain has a direct effect on terrestrial plant mortalities.
In this lab, you will test this hypothesis by exposing seeds to acid rain to determine if
germination is influenced.
Forming a Hypothesis:
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Materials:
acid rain
graduated cylinder
seeds
beakers
2 Mini-Petri dishes
pH paper
filter paper
scissors
Setting up a Controlled Experiment:
1. Obtain two Petri dishes one labeled R (rain) and AR (acid rain).
2. Using scissors cut the filter paper to fit the bottom of each Petri dish.
3. Count out 40 healthy looking seeds and randomly scatter exactly 20 seeds into each
Petri dish taking care that each seed is in contact with the filter paper.
4. Measure 5 ml of (rain) water using the graduated cylinder. Gently pour the water
into the Petri dish labeled rain and place the cover on top.
5. Take a piece of pH paper and test the pH of the water in the decanting beaker.
Record your results in table # 1.
6. Measure 5 ml of acid rain using your graduated cylinder. Gently pour the acid rain
into the Petri dish labeled acid rain and place the cover on top.
7. Take a piece of pH paper and test the pH of the acid rain in the decanting beaker.
Record your results in table # 1.
8. Place both Petri dishes in the window and observe your results in 24 hours.
9. Clean up your work station and rinse graduated cylinder with water.
What was the manipulated or independent variable in this experiment?
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What was the responding or dependent variable in this experiment?
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State at least 5 variables that were held constant during this experiment.
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Which Petri dish was the control group in this experiment?
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Which Petri dish was the experimental group in this experiment?
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Recording and Analyzing Results
Water
pH Paper
Describe the appearance of
the seeds after 48 hours
Total Number of Seeds
Total Number of Seeds That
Germinated
Percent of Seeds That
Germinated
Table # 1
Acid Rain
In the space below, sketch a germinated seed using a dissecting microscope located on your
bench. Please note: ALL MICROSCOPE SKETCHES ARE TO BE DONE IN PENCIL.
State a Conclusion:
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State any possible sources of error:
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