David

Planning an Experiment—Biology Trimester Investigation Plan due on Friday, April 27th

EACH STUDENT IS RESPONSIBLE FOR WRITING UP A CLEAR PLAN FOR YOUR INVESTIGATION, EVEN IF YOU ARE WORKING IN A GROUP.

Question(s) for investigation:

Does phosphate limit nutrition for algae growth? If it does, how does it affect it?

Independent variable and how it will be measured:

In four test tubes, different amount of phosphate will be dropped, and hopefully, each amount of phosphate dropped into the tubes would affect the growth of algae differently.

Dependent variable(s) and how it (they) will be measured:

The dependent variable will be the growth of algae in each different test tubes. The growth will be measured by the length of algae. If the growth is not shown through the length, it will be measured by the weight.

Variables held constant:

The same pond water The same environment (such as temperature) The same type of phosphate The same kind of test tubes The same amount and kind of algae

List of Materials and Sketch of the Setup:

Dropper pipette Algae culture 4 test tubes with stoppers Test-tube rack 50-ml graduated cylinder Pond water Glass-marking pencil 10% trisodium phosphate solution

Who else will work on this investigation? Who will be responsible for collecting materials to get started and when will all materials be ready to begin? Procedure/Method:

1. Get things prepared. 2. Use a dropper pipette to put 20 drops of algae culture into the four test tubes each. 3. Add 19mL of pond water to each test tube. 4. Use the glass-marking pencil to label one as “control”, and to label the others the amount of phosphate added. 5. Close the tips of the test tubes with stoppers and put them in a sunny place. 6. Wait for a week. 7. Observe the test tubes.

Data:
 * Make a blank data table which you plan to fill out during the investigation
 * What other data do you expect to include in a report of your results?


 * **Amount of phosphate** ||
 * Control ||
 * 2 drops ||
 * 4 drops ||
 * 6 drops ||
 * =Algae growth= ||  ||   ||   ||   ||   ||
 * =Algae growth= ||  ||   ||   ||   ||   ||

Expectations: · What do you think might happen and why? In my opinion, since phosphate is environmentally dangerous thing, phosphate might affect the growth of algae. I think it would slow down the growth of algae, slowing it more and more down as the amount of phosphate is added.

· What other results do you imagine might happen and what would they mean?

I think when the amount of phosphate reaches to a certain point, it might stop growing. If the amount of phosphate exceeds the enough amount, the algae would not be able to handle it and just stop growing.

Communication: I will first tell the people what kind of substance phosphate is, and explain how it affects the growth of algae.
 * How will you plan to communicate your work clearly to others?

I expect to figure out the relationship between algae growth and phosphate, and also if the other result I guessed is correct.
 * What do you expect to accomplish in EACH of the next three class periods in which you can work on this investigation?

At first, I thought phosphate would slow the growth of an algae because it is environmentally dangerous substance. However, from searching throughly on the Internet, I found out that phosphate stimulates and quickens the growth of algae, resulting in water poisioning. This fact is totally different from what I had expected.