Hey there!
Pluto crossed Neptune's orbit. However, their paths do not actually cross, they just swap positions.
Hope that helps!
~Autumly
Answer:
Semi-conservative
Explanation:
Meselson–Stahl experiment proved that DNA replication is a semiconservative process, feeding E. colo bacteria with different types of Nitrogen isotopes (N14 and N15).
Changing the type of radioactive compound in different times of bacteria grow, they could observe that both of the isotopes were present on the bacteria culture.
Basically, if the bacteria present both of them, the DNA was replicated semiconcervely.
Guess what? they show both! (See the image for more information)
The definitions of "sector 3" and "stratum D", the layout of the sectors,
and the behavior of the strata would go a long way toward explaining
that mysterious absence.