Yes, there are! You can find links to the suggested answers in "Teacher notes" section of each unit:
Teacher notes contain a number of useful bits of information, including printable handouts in PDF format, as well as model answers!
With our original unit format, answers to all lessons are bundled into a single PDF:
The new unit format breaks answers up and they can be downloaded on a per-lesson basis:
Double Helix Lessons by CSIRO
DHL groups them together like this: