Needs to be answerd right away, a mutagen is a)a living thing that has undergone a mutation. b)an agent that causes a mutation in dna. c)a mutation that has affected one gene. d)a chemical that can poison living cells.

Match the correct terms to their descriptions a system in which only energy but not matter is exchanged frozen water in snow part of geosphere that includes only soil a thin layer between the troposphere and the stratosphere cryosphere tropopause closed system pedosphere