What type of system represents the cycling of energy on the earth?
a. mixed system
b. open system
c. closed system
d. energy system

Tlymphocytes mature in the? a. thyroid gland. b. bone marrow. c. spleen. d. thymus.

List the advantages and disadavantages of the switch from persistent chlorinated hydrocarbon pesticides (such as ddt) to nonpersistent organophosphate pesicides. have the benefits of the switch outweighed the disadvantages? explain.

Moving down the ramp from 6 meters to