Research Question: How does fertilizer effect the growth of Lemna (Duckweed)? Hypothesis

Дата канвертавання22.04.2016
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Research Question: How does fertilizer effect the growth of Lemna (Duckweed)?
Hypothesis: If there is more fertilizer in the water, then the Lemna will grow faster, because water normally has minerals of phosphate, nitrate and potassium in limiting supply. If a fertilizer containing phosphates, nitrates and potassium is added to the water then these factors will not be limiting anymore and faster growth will occur.




  • Pure water

  • 4 cups or Petri dishes

  • Stock fertilizer

  • 100ml of each solution below:

  • ½ concentration fertilizer (8 drops/100mL)

  • ¼ concentration fertilizer (4 drops/100mL)

  • 1/8 concentration fertilizer (2 drops/100mL)

  • 1/16 concentration fertilizer (1 drops/100mL)


  1. In pairs set up the following containers.

  2. Each solution should have 2 cups with 100ml of fluid in it. Label carefully.

  3. Make a mark on the outside of the cup of the fluid level. This level must always be kept – so if evaporation occurs it will not have such an impact on your results.

  4. Add 10 leaves of duckweed (Lemna) to each container. Ideally add 10 individual leaves.

  5. Each week record in a table the number of leaves (fronds) in each container.

  6. You will be collecting data for 3-4 weeks.


Collect and record a sheet of class data and to use as additional trials for this experiment.

Draw up a neat table of your data.

Process and manipulate your data.

Graph your processed data.
Discussion /Conclusion/Evaluation:

Using the hypothesis at the beginning of the sheet make a conclusion and evaluate the experiment and give errors and ideas for improvement.

Experimental Problem #2 (Original Problem)

These experiments should be original. Some possible ideas:

*Design an experiment that could be used to compare the effects of nutrient enrichment on two different bodies of water
*Design an experiment to determine what types of household items might be contributing to cultural eutrophication (i.e.: many detergents contain phosphorus, lawn fertilizer contains nitrogen).
*Design an experiment to determine whether or not there is a marked difference in the biological consequences of continuous low-level nutrient enhancement and sudden high-level nutrient enhancement.
Materials Available

Research Question:__________________________________________________________________________________________________________________________________________________________________________________?


Independent Variable: What are you adding/changing in your experiment?_________________________

Dependent Variable: What are your measuring? How do you know eutrophication is occurring?________________

Controls: What aspects are you keeping the same in each group? _________________________

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