Final answer:
The faulty parallel structure is in the fragment 'preserves using whole fruit', as it does not match the 'is made by' construction of the other parts of the series. It can be corrected by revising it to 'is made with whole fruit preserves'.
Step-by-step explanation:
The portion of the sentence that contains a faulty parallel structure is "preserves using whole fruit". This fragment does not follow the pattern established by the other fragments in the series, which begin with "is made by". To correct the parallelism, it could be revised to match the structure of the other parts, for instance, as "is made with whole fruit preserves".
Parallel structure is important in English as it improves readability and ensures that similar ideas are expressed in the same grammatical form, providing clarity and balance to writing. Mixed-construction sentences can negatively impact the coherence of a text, thus effective revision is crucial.