After a wheat field is cleared, wild grasses and weeds begin growing. This process is considered-

Oil spills in the ocean affect marine food webs.  Animals that are initially affected by oil spills include sea otters, seabirds, and other organisms that spend most of their time on the ocean surface.

Based on the food web, how would a significant decrease in the sea otter population due to an oil spill most likely affect this ecosystem?

Refer to the illustration above. Because the two species of barnacles attempt to use the same resources, they are

Which statement best describes the differences in species diversity between an ecosystem beginning the process of primary succession and one beginning the process of secondary succession?

____     Below is an example of a segment of a natural biogeochemical cycle.  Which cycle is represented by this segment?

In an experiment, two plants are grown together for a time, and then separated.

Plant 2 is a parasite of Plant 1.

Which graph best predicts the growth of Plant 1 and Plant 2 during the experiment?

A student is studying the ecology of a playa lake, which forms after rainfall in a dry lake bed.  The table below lists the organisms that the student observed.

Which level of biological organization has the student described in the table?