Name: _______________________________ Hour: ________________
LS2-1 Checkpoint Review
1. Sketch a graph of logistic growth and explain the important parts of the graph.
Exponential phase: rapid growth, no limits on growth.
Transitional phase: growth slows, limiting factors start
to have an effect on the population.
Plateau phase: growth stops, population size stabilizes
2. Sketch a graph of exponential growth.
3. Name and describe the density-dependent limiting factors discussed in class.
Competition – crowded populations compete for resources and mates. Denser
populations compete more since resources are used more quickly.
Predation – an increase in prey will result in an increase in predators and vice-versa.
Herbivory – (preying on plants) same dynamic as predation with fluctuating populations
Parasitism and disease – denser populations are more efficient at transmitting disease
from one individual to the next.
Stress from overcrowding – overcrowding leads to competition and death of individuals
who cannot adapt.
4. Name and describe some density-independent limiting factors from class.
Density-independent limiting factors are factors that affect a population regardless of
size. Examples include most natural disasters like floods, hurricanes, etc. since
population density does not play a specific role in whether the population is affected.
5. Could you describe some density-independent limiting factors as being more like densitydependent limiting factors? Explain.
Yes, because once a natural disaster like a hurricane reduces the available resources,
organisms will compete for the remaining resources. This behavior is one of the densitydependent limiting factors since population density determines whether or not there is
competition. The natural disaster artificially increased the population density.
6. What is carrying capacity? What determines the carrying capacity?
Carrying capacity is the maximum number of individuals of a species an environment can
support. It is determined by the presence of limiting factors.
7. Describe the role that density-dependent and independent limiting factors play in determining
the carrying capacity.
Density-dependent limiting factors, such as amount of food, affect populations once they
reach a specific population density. Once these factors prevent further growth of a
population, it has reached its carrying capacity. Density-independent factors may change
the carrying capacity by either removing or adding resources. For example, a hurricane
reduces the amount of food and living space in an area, thereby reducing the carrying
capacity of many species. However, the hurricane adds large amounts of water to an
area, thereby producing new breeding grounds for mosquitoes and increasing their
carrying capacity.