Name:___________________________________________Date___________ Period ________
Virtual Lab: Population
Biology
How to get there- can link directly from the Ecology
Subfolder on my website by opening the a copy of this
document called “Virtual Population Lab” and clicking on
the hyperlink: ( http://glencoe.mcgraw-hill.com/sites/dl/free/0078757134/383928/BL_04.html ).
Read the background information on the paramecium. One important thing to note is that these
two microorganisms do not feed on each other, but they do eat the same type of food (rice in this
case).
1. What are the objectives for this experiment?
Follow the directions to view the population sizes for the 3 different tubes (1 with P. aurelia
alone, 1 with P. caudatum alone and one with both species.) To make it easier to share the
counting with your table partner, click on the “Grid On” button on the microscope so that the
microscope view will be divided into sections.
Data Table
P. aurelia grown
alone, cells/mL
Day O
Day 2
Day 4
Day 6
Day 8
Day 10
Day 12
Day 14
Day 16
P. caudatum grown
alone, cells/mL
P. aurelia grown in
mixed culture, cells/
mL
P caudatum grown
in mixed culture,
cells/mL
3. Make a graph of the data using the graph paper at the end of this packet. Be sure to have the
responding (dependent) variable on the vertical axis, to include units and have even increments
for your scale. Your graph will have four lines (draw best fit curves for each set of data). Be
sure to include a key to distinguish between the different groups.
4. Explain how you tested your hypothesis.
5. On what day did the Paramecium caudatum population reach the carrying capacity of the
environment when it was grown alone? How do you know (relate your answer to the graph). ?
6. On what day did the Paramecium aurelia population reach the carrying capacity of the
environment? How do you know?
7. Explain the differences in the population growth patterns of the two Paramecium species.
What does this tell you about how Paramecium aurelia uses available resources?
8. Describe what happened when the Paramecium populations were mixed in the same test tube.
Do the results support the principle of competitive exclusion? (You may need to research the
meaning of competitive exclusion using your iPads.)
9. Explain how this experiment demonstrates that no two species can occupy the same niche.