It is mainly the skills and concepts that you have learnt that will be carried on eg essay/short answer writing skills. There are exceptions of course.
30% of maths carries on.
Depending on whether you school does it or not, Projectiles carries on for physics. The bonding, gravimetric analysis, mole equations, pH knowledge, writing equation skills carry on for chem.
Sometimes, they will ask you direct questions from the year 11 syllabus or in the case of maths, a question from a lower level of maths.