Which of these are measures of quantity?
3 moles of sand grains on a beach
25-pound bag of sugar
16 gigabytes of memory
2-liter bottle of soda

#7 how does the structure of amino acids allow them to form a polypeptide? each amino acid has an amino group and a carboxyl group. each amino acid has a hydrogen atom and a carboxyl group. each amino acid has a carboxyl group and an r group. each amino acid has an r group and a hydrogen atom.