Which of the following statements are not true?

1. Transposition occurs by only nonreplicative mechanism.
2. Homologous recombination between multiple copies of a retrotransposon causes rearrangement of host DNA.
3. Homologous recombination between the repeats of retrotransposon may lead to imprecise excision.
4. Imprecise excision describes the removal of a transposon plus one of the duplicated target sequences from the chromosome.

Transposition occurs by both Replicative and Nonreplicative Mechanisms. All transposons use a common mechanism in which staggered nicks are made in target DNA, the transposon is joined to the protruding ends, and the gaps are filled. The order of events and exact nature of the connections between transposon and target DNA determine whether transposition is replicative or nonreplicative. Precise excision describes the removal of a transposon plus one of the duplicated target sequences from the chromosome. Imprecise excision occurs when the transposon removes itself from the original insertion site, but leaves behind some of its sequence.