Name ______________________________________________ Per. _______Date __________
Virtual Population Biology Lab
http://www.mhhe.com/biosci/genbio/virtual_labs_2K8/pages/PopulationBiology.html
Go to the website listed above and click on the link for “Laboratory Exercise.” Read the background information
and the directions for the lab. Answer the reading questions on the first page of this sheet. All your data will be
collected in the table on the back of the sheet. Graph your data. This sheet and your graph will be taped into
your notebook. Finally, answer the analysis questions in your notebook.
Reading Questions: (Answer on this sheet.)
1. What qualifies as “ideal conditions”?
2. What type of growth pattern occurs under ideal conditions? Define this term.
3. What do we call the point at which a population’s size remains stable? Define this term.
4. What limits population growth?
5. Name at least three resources that individuals or groups of populations would compete for.
6. Explain the difference between intraspecific and interspecific competition.
7. What is competitive exclusion?
8. How do genetic differences affect competition? What will the effect be on future generations?
Experiment: Follow Procedure steps 1 and 2. Now 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 (If…then… because…)
Data Collection: Continue with the experiment, following steps 4-10, except in step 8, record your data in the
table below.
Data Table
Day
P.
caudatum
alone,
cells/mL
P.
aurelia
alone,
cells/mL
P.
caudatum
mixed,
cells/mL
P.
aurelia
mixed,
cells/mL
Explain how you tested your hypothesis.
0
2
4
6
8
10
12
14
16
Analysis: On a ½ sheet of graph paper, make a line graph for each of the different samples: P. caudatum alone,
P. caudatum mixed, P. Aurelia alone, and P. Aurelia mixed. Make sure you follow all the rules for making a
graph. Each bacteria sample should be a different color and you should provide a key. (Tape into notebook.)
Analysis Questions: (Answer in notebook.)
1. For each of the cultures grown alone, what type of growth line is shown over the first several days? What
type of growth line occurs over the entire time period of the experiment?
2. On what day did the Paramecium caudatum population reach the carrying capacity of the environment when
it was grown alone? How do you know?
3. On what day did the Paramecium aurelia population reach the carrying capacity of the environment? How
do you know?
3. 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?
4. Describe what happened when the Paramecium populations were mixed in the same test tube. Do the results
support the principle of competitive exclusion? Explain.
6. What do you think would happen if you added a third species of Paramecium to the mixture? Why?
7. Identify and explain two limiting factors in this experiment.