Imagine a root which has to grow exposed to air above ground. It would dry out quickly, so a cuticle should be added. This would make these roots superior for growth of plants in a wide range of very dry places which are now inaccessible, or nearly so, for vascular plants.
Work Step by Step
This is a very wide-open question (this chapter has a number of questions in it which need rewriting, but you have to use it). To start, pick one of the structures to redesign, and think about it's normal purpose. Then try to imagine a stressful situation and how to modify the structure to survive that.