What benefit does the size of the Earth serve? 

A)  Its size keeps it in orbit at a constant distance from the sun. 
B)  Its size provides enough gravitational mass to keep the light gaseous molecules in its atmosphere from flying off into space. 
C)  Its size keeps the iron-nickel core solid. 
D)  Its size prevents transfer of geothermal energy to the surface of the planet.

Phytoplankton flourish most abundantly in the bathyal zone on the ocean.

Which organism is considered a tertiary consumer? 

A)  jellyfish 
B)  zooplankton 
C)  phytoplankton 
D)  osprey

Which of the following is true about the formation and migration of meanders?

A) most floodplains do not preserve evidence of the former position of meanders
B) flow velocity is highest when water takes a shortcut around the inside of a bend
C) meanders migrate inward as sediment is deposited on the inside bend
D) migration of meanders back and forth can help form a floodplain
E) none of these