Final answer:
The claim that composite transposons require both arms to have a functional transposase is false. Only one functional transposase is necessary for the transposition of the entire composite element.
Step-by-step explanation:
The statement "Composite transposons need both arms to have a functional transposase" is false. Composite transposons, or Tn elements, are made up of two insertion sequences (IS elements) that flank a central region, which may carry additional genes such as antibiotic resistance genes. For transposition to occur, only one of these IS elements needs to contain a functional transposase gene. The transposase produced can facilitate the movement of the entire composite transposon. An example of a component of a composite transposon that lacks this enzyme yet can still transpose is the maize Ds element, which requires the autonomous Ac element to provide the necessary transposase.