Duckweed Population Growth Rate at Different pH of Water (Jennifer Kim)

2. Place about 200 mL of water in the three different cups with their respective pH levels. I used a special water filter that is able to appropriate pH levels

3. Place the cups in location where they will all be able to get equal amount of sunlight during the day.

4. Put 10 duckweed plants in each of the three labelled cups

5. Record the duckweed population in each of the three cups, once a week for two months. Remember one duckweed "leaf" is actually one duckweed plant.

Independent variable

The independent variable is pH 4, pH 7, and pH 10.

Dependent variables

The dependent variable is the number of duckweed plants.

Series

The series that will be tested is the number of duckweed plants as a function time at various pH levels.

Constants and Controls

The factors that will be held constant are the volume of water and the hours of sunlight exposure.

The control is the duckweed at pH 7.

Materials

• 3 plastic cups

• black sharpie pen

• 100 mL graduated cylinder

• duckweed which can be purchased with Carolina Biological Supply Company (http://www.carolina.com/)

Procedures

1. Label one plastic cup with pH 7. Label the second plastic cup with pH 4, and label the third plastic cup with pH 10.

2. Place about 200 mL of water in the three different cups with their respective pH levels. I used

a special water filter that is able to appropriate pH levels3. Place the cups in location where they will all be able to get equal amount of sunlight during the day.

4. Put 10 duckweed plants in each of the three labelled cups

5. Record the duckweed population in each of the three cups, once a week for two months. Remember one duckweed "leaf" is actually one duckweed plant.