Final answer:
DNA polymerase recognizes an incorrect base during DNA replication because hydrogen bonds cannot properly form between mispaired bases, and through its proofreading function, it excises the incorrect nucleotide before adding the correct one.
Step-by-step explanation:
The question is centered on how DNA polymerase can recognize an incorrect base during DNA replication. DNA polymerase is an enzyme that synthesizes DNA molecules from deoxyribonucleotides, the building blocks of DNA. When DNA polymerase encounters a base that has been incorrectly paired, the correct base-pairing is not formed because hydrogen bonds cannot properly be established between the incorrect bases. Additionally, DNA polymerase has a proofreading function where the enzyme reads the newly added base before adding the next one, and if a mispairing is detected, it performs a cut at the phosphodiester bond holding the incorrect nucleotide and then excises it with its 3' exonuclease activity. Once the incorrect base is removed, the correct base can then be incorporated into the DNA strand.