Single-strand breaks in a DNA molecule are most likely to lead to which outcome?

• A. Automatic repair
• B. Partial repair with possible negative effects to the DNA molecule
• C. Non-repair that can lead to mutation, carcinogenesis, or cell death
• D. Repair without negative effects to the DNA molecule

Answer: (D)

Single-strand breaks are handled by dedicated repair systems in the cell, which quickly and accurately restore the DNA backbone. When this damage is repaired before the DNA is replicated, the original sequence is restored without introducing changes, so there are no negative effects on the molecule. This is why the most likely outcome is repair without adverse effects. If the break remains unrepaired and replication occurs, problems such as mutations or cell death can arise, but those are outcomes of unrepaired damage, not the typical result when repair works properly.