Which statement is true of arteries? a. they prevent blood from flowing backwards b. they carry oxygen-poor blood toward the heart c. they become smaller as they move away from the heart d. they have walls that are one cell thick

Vegetation that grows along the floors of tropical and temperate forests is called undergrowth. how is the undergrowth of a tropical rain forest most likely to differ from the undergrowth of a temperate forest? a. a tropical rain forest's undergrowth most likely experiences periods of dormancy during colder weather. b. a tropical rain forest's undergrowth most likely experiences periods of dormancy during rainy weather. c. the undergrowth of a tropical rain forest most likely requires less sunlight. d. the undergrowth of a tropical rain forest most likely requires more sunlight.

Animals such as pronghorn antelope, bison ans badgers dot to the landscape. where are these animals located?

Consider the model of the oxygen cycle on earth. the majority of earth's oxygen reservoirs are found in the a) atmosphere. b) biosphere. c) hydrosphere. d) lithosphere.