Virtual Lab: Population Biology

  1. Type in the lab url (
  2. The left side of the page contains background information and instructions in the “Question” area. On the bottom of the page are the following icons for your use: “Journal” (these are questions that may be answered/submitted to your instructor), “Calculator” (working calculator function), “Data Table” (where you may be submitting your collected data from the exercise), “Audio” (turns sound on/off) and “Print” (prints the screen).
  3. Read the information in the window that initially opens, and when you are through close the window by clicking the “X”. You can reopen the window for further reference by clicking the “Information” button found on the laboratory area. Next, please read the background information within the “Question” area, continuing on to the procedure information posted there as well.
  4. At this point, you are ready to begin the lab exercise. Click on the purple bulb of one of the pipettes to begin transferring your first culture. Remember to follow the directions given to you in the “Question” as well as in the “Post-Lab Quiz and Lab Report” areas, and refer back to the notes in the “Information” area if necessary.
  5. Complete the exercise as directed, recording any data or information needed in your “Data Table” and/or “Lab Report”.
  6. When you are finished, please answer all of the questions found at the end of the “Post-Lab Quiz and Lab Report”.

*****This lab has instructions on the left hand side and also contains pages to enter data and questions. Due to the trouble with submitting documents and data this way, it is preferable to just turn in a handwritten or typed copy. Print this out for copies, or use the Word Document to type directly into the tables (preferred).

Data Table
P. aurelia grown alone, cells/mL / P. caudatum grown alone, cells/mL / P. aurelia grown in mixed culture, cells/ mL / P caudatum grown in mixed culture, cells/mL
Day O
Day 2
Day 4
Day 6
Day 8
Day 10
Day 12
Day 14
Day 16
Journal
1. What are the objectives for this experiment? (you can summarize)
2. Make a hypothesis about how you think the two species of Paramecium will grow alone and how they will grow when they are grown together.
3. Explain how you tested your hypothesis.
4. On what day did the Paramecium caudatum population reach the carrying capacity of the environment when it was grown alone? How do you know?
5. On what day did the Paramecium aurelia population reach the carrying capacity of the environment? How do you know?
6. 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?
7. 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 briefly explain what competitive exclusion is)
8. Explain how this experiment demonstrates that no two species can occupy the same niche.