Define Ecosystem Boundaries Practice Test

Ecosystem model: Students are modeling a city park meadow. A dashed boundary outlines a 30 m × 30 m meadow patch. Inside are grasses, clover, bees, butterflies, rabbits, soil, puddles after rain, and sunlight. Outside are a line of trees that shade part of the meadow, a dog-walking path where dogs sometimes chase rabbits, and air pollution from a nearby street. The students write: “System boundaries are chosen for modeling purposes.”

Which boundary best represents the ecosystem being studied if the goal is to measure how shade affects flower growth in the meadow patch?

Ecosystem model: A class is modeling a prairie grassland plot that is a 20 m × 20 m square marked with flags (the boundary is a dashed square). Inside the boundary are grasses, wildflowers, grasshoppers, prairie dogs, hawks flying overhead, fungi in soil, soil moisture, and rocks. Outside the boundary are a road (noise and dust), a stream 50 m away that affects groundwater, and a cattle pasture that sometimes brings grazing animals onto the plot. The class states: “System boundaries are chosen for modeling purposes.”

Which statement about boundaries is supported by the ecosystem model if the goal is to study how grazing changes plant height inside the plot?