Population Ecology
Scientific Background
In nature, organisms interact, and these interactions often effect ecosystem dynamics
and population sizes. The predator-prey relationship is an important interaction among
populations in all ecosystems.
Writing Task
Document A shows the population sizes of three species: a small herbivore, a larger
herbivore, and a carnivore. Describe the information provided by the graph and how
each species affects the sizes of the others.
In your essay, be sure to complete the following tasks:
- Identify the curve that represents each of the species listed in Document A and give
examples of possible organisms within a forest ecosystem that might represent each
species.
- Describe the changes in the population densities of these three species over time.
- Explain what would happen to population B if population C were to disappear.
(Documents A through C are related to this Writing Task.)
Each Gateway Test form is constructed with the following features:
 Scientific Background
 An overview of the Writing Task
 Two to three specific bullets that must be addressed in each response
 Scientific documents for analysis and interpretation
DOCUMENT A
DOCUMENT B
DOCUMENT C