Final Answer:
Smaller fragments of DNA migrate further in an agarose gel during electrophoresis because they experience less resistance from the gel matrix.
The gel matrix acts as a sieve, and smaller fragments can more easily navigate through the pores, allowing them to travel a greater distance in the electric field compared to larger fragments.
Step-by-step explanation:
The final answer reiterates that smaller DNA fragments encounter less hindrance from the gel matrix, which functions like a sieve. The explanation emphasizes that smaller fragments can navigate through the gel pores more easily, leading to a more extended migration distance during electrophoresis.