Earth is comprised of four systems, or spheres. describe how these four spheres work together as a system.

Of the pollutants that form acids in the atmosphere, which is easiest to reduce? a. sulfur dioxide b. nitrogen dioxide c. ozone d. carbon monoxide

Most of the fossils found in virginia are in the coastal plain, valley, ridge, and appalachian plateau regions, best suggesting that these geographic provinces a) were once covered by seawater. b) are the oldest parts of virginia. c) have a great deal of karst topography. d) have large amounts of sedimentary rock.

What is the definition of genes? a. small rna chains that transfer a specific amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation b. sections of dna a cell copies as rna strands to make specific proteins during transcription and translation c. molecules of rna encoding a chemical blueprint for a protein product