Economic systems
natural systems.
a. operate within
b. are independent of
c. have no relation to
d. are equal to

Most of earth’s fresh water is found in oceans and seas stored in glaciers and ice caps groundwater stored beneath the surface found in lakes, rivers, streams, and reservoirs

In addition to seeds, which of the following characteristics are unique to the seed-producing plants? a) sporopollenin b) lignin present in cell walls c) pollen d) use of air currents as a dispersal agent e) megaphylls

Give three examples of plant activities that are affected by circadian rhythms and natural fluctuations in the length of daylight?