I assume when you're talking about literary worlds you're referring to the unseen section (Section 1) that will come in the exam.
Treat it like an extension of short responses in advanced eng. The critical responses tend to be longer in extension (and could be worth 10, 15 or 20 marks).
Start with your broad thesis statement linking to literary worlds, and then have a second statement more direct to the question/unseen text. You should use quotes from the text provided and analyse them because this will build on to your thesis. You don't necessarily need to include critical theories for your unseen text, but it can be done if you want (I've seen exemplar responses with and without critical theories - it's more important in your essay as it's based on texts you have spent the whole year breaking down and drawing connections between them).
As for structure, you're quite free with it. You obviously need that intro statement and a concluding statement, but how you spread out your paragraphs is up to you, as long as it's cohesive. Again, depending on how many marks it's worth, the length of your response will vary. It's always a good idea to jot down a quick plan of how you want to respond to the question, and how you will use the text.
Hope this helps