Refer to the graph showing changes in atmospheric CO2 concentrations in the Northern Hemisphere beginning in 1960.        What is the overall trend in CO2 concentration, and what causes the yearly seasonal fluctuations?

Which group of animals is endothermic?

Before Hurricane Katrina devastated New Orleans in 2005, humans had vastly changed the area. They had destroyed wetlands, extracted oil and gas (which led to sinking of the ground), constructed dams and levees, dredged, and built channels for ship traffic. Also, rising sea levels had caused the death of some cypress swamps. These changes suggest that development of New Orleans destroyed which major ecosystem service that might have lessened the hurricane’s devastation?

An example of a trait controlled by multiple alleles is  

An area with moderately low precipitation and moderate temperature that may feature a chaparral as a biome subset.

Amoebas, foraminiferans, radiolarians, and heliozonas are all classified as _____.

The grinding apparatus of the digestive system of the crayfish is/are the

During succession, two plant species become established at different times. Species A is a perennial with roots that secrete chemicals to maintain a distance between members of the species and similar species. Species B is a low-growing annual with nitrogen-fixing bacteria in its root nodules. Which (if either) of these two species most likely appears first during succession, and why?

An imported plant escapes from a greenhouse and begins to grow outdoors. Unnoticed at first, it proliferates and its seeds begin to spread. After several years, it occurs in the wild in several states. The plant grows faster than many native species and is difficult to eradicate. Which is the most likely result of this plant’s introduction into the ecosystem?

A survey of a pond community identified 57 different species that made up the community. This number can best be described as a measure of the community’s