Which soil horizon, also known as the zone of accumulation, is enriched in clay, iron oxides, silica, carbonate, and other materials?
A) A Horizon
B) B Horizon
C) C Horizon
D) O Horizon
E E Horizon

Which of the following statements is true? a. the main cause for speciation is an increase in gene flow. b. organisms that reproduce asexually are not considered part of a species. c. on a tree of life diagram, speciation is shown by the merging of two different lineages. d. the size of the geographic area inhabited by a population can cause speciation.

Compare and contrast region e in the illustration above with region d. describe the physical characteristics of each region.

Which of these is an example of land degradation? a. containers designed to store pollutants leak. b. fertilizers provide too many nutrients to crops. c. garbage is buried so the land can be reclaimed later. d. a drought kills all the plants in an area, leaving bare land