If the same base pairs are used to code for all organisms, why is there so much vairation among organisms

If a strand of dna has 35% thymine. what is the percentage of cytosine, adenine, guanine?

What organ is the first to receive nutrients that have been absorbed from the digestive tract?

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