The nitrogen utilized by most plants is derived from

a. soil.
b. the atmosphere.
c. nitrogen gas.
d. decayed organic matter

South america is located within which hemisphere?

In the following diagram, four different index fossils are labeled: which of the labeled fossils comes from the oldest organism? a b c d

Which of the following statements best characterizes changes to agriculture in the united states since 1900? a. increased mechanization has reduced the need for labor.b. increased mechanization has increased the need for water, thereby increasing the need for labor.increased mechanization has increased the use of land, thereby increasing the need for labor.d. increased mechanization has increased food production, thereby increasing the need for labor. select the best answer from the choices provided.