Question

select the true statements. all four dna nucleotides have identical nitrogenous bases. all four dna nucleotides have identical 5-carbon sugars. all four dna nucleotides have identical phosphate groups.

Explanation:

• For the statement "All four DNA nucleotides have identical nitrogenous bases": The four DNA nucleotides have different nitrogenous bases (adenine, cytosine, guanine, thymine), so this statement is false.
• For the statement "All four DNA nucleotides have identical 5 - carbon sugars": Each DNA nucleotide has deoxyribose as the 5 - carbon sugar, so this statement is true.
• For the statement "All four DNA nucleotides have identical phosphate groups": All DNA nucleotides have the same phosphate group structure ($\ce{ - O - P( = O)( - O^ - ) - O - }$), so this statement is true.

Answer:

• All four DNA nucleotides have identical 5 - carbon sugars.
• All four DNA nucleotides have identical phosphate groups.