In DNA replication theory, which hypothesis proposes that parental DNA is broken into fragments and each daughter molecule contains interspersed mixtures of old and new DNA throughout both strands?

Introduction / Context:Before the Meselson–Stahl experiment, multiple models were proposed for how DNA duplicates. This question distinguishes among conservative, semi-conservative, and dispersive replication models.

Given Data / Assumptions:

• The hypothesis described says parental DNA is fragmented.
• Daughter DNA strands are mosaics: both strands contain alternating old and new segments.

Concept / Approach:Match the described mosaic pattern to the formal model names. The dispersive model uniquely predicts mixed old/new DNA along both strands after each round.

Step-by-Step Solution:1) Conservative: parental duplex remains intact; a wholly new duplex is made. Not a mosaic.2) Semi-conservative: each daughter duplex has one old strand and one new strand; strands are not internally mixed.3) Dispersive: both strands in daughters consist of interspersed old and new DNA fragments, matching the description.

Verification / Alternative check:Meselson–Stahl density data excluded pure conservative after one generation and later excluded dispersive due to observed strand patterns after additional generations and nicking/denaturation tests.

Why Other Options Are Wrong:Conservative and semi-conservative do not predict internal mixing of old/new along the same strand; “evolutionary theory” is not a DNA replication model.

Common Pitfalls:Confusing “semi-conservative” (one old + one new strand) with “dispersive” (mosaic within each strand).

Final Answer:Dispersive theory