They can estimate how old the universe is by testing rocks from different planets and comparing ages and comparing with our earth so since we know approximately how old are earth is we can tell how old the universe is
A swamp has an exess in trees and stuff where as a marsh doesn't
Amino group, carboxyl group, hydrogen atom, and variable group (represented with R). The r-group is a side chain and amino acids are grouped together by their side chains. The product of these groupings may be hydrophobic or hydrophilic.
