The most common usage for the pilus in bacteria is to:

The insects were the first organisms to

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?