PRACTICE QUIZ
Checkpoint LS2-1
“I can use data to explain that living and non-living resources affect the carrying capacity of an
ecosystem
1. Define Carrying Capacity and give an example:
Carrying Capacity is the maximum number of individuals of a species an environment can
support. For example, a petri dish will only support a certain number of bacteria (about
21,000 in our lab that we graphed).
2. Answer the following questions by looking at the graph below.
(Months)
a. What is the carrying capacity in this environment?
Approximately 1,000 individuals.
b. At approximately what time did exponential growth begin?
At approximately 20-40 months.
c. At approximately what time did the transition phase begin?
At approximately 60-70 months.
d. At approximately what time did the plateau phase begin?
At approximately 70-80 months.
3. Define a density-independent limiting factor and provide one example.
A density-independent limiting factor is a factor that affects all populations in similar
ways, no matter the population size or density. An example is a natural disaster, like a
flood.
4. Define a density-dependent limiting factor and provide one example.
A density-dependent limiting factor is a factor that depends on the amount of organisms
in a unit area. An example is a resource, like food, or a disease.
5. In class, we discussed limiting factors as being two groups, density-independent and densitydependent. How could you argue that there are no true density-independent factors? Explain
your answer and be sure to include examples.
There may be no true density-independent limiting factors because they affect
populations by removing a resource (like food, water, living space, etc.) which then
engenders competition among the remaining organisms. Competition is a densitydependent limiting factor.
6. Which density-independent factor do you believe is the most harmful to a population of
squirrels in an urban area? Why did you make this choice?
Answers vary. Possible answers could include traffic, weather, etc.
7. The following 3 questions pertain to human populations.
a. What density-dependent factor do you believe to be the most harmful to humans?
Answers vary.
b. Why did you make this choice?
Answers vary.
c. What are humans doing to address this problem?
Answers vary.