It's been said but for posterity...
Physics, like Bio, doesn't test you directly on what you learnt, but a lot of the underlying foundations of what you'll learn in Year 12 will be assumed knowledge. So they may test you on something in the syllabus from year 12 that required assumed knowledge from Year 11.
Ancient History, I can't quite remember. I vaguely remember things crossing over (as cem has said), and again there is an element of assumed knowledge, but they can't examinate you on something from the Year 11 syllabus if you haven't crossed over and done the same/similar topic in Year 12.
I see you're in year 11 at the moment, so I wouldn't be too worried about the HSC just yet. Get the best marks you can for Year 11, and it will be a good indicator of what you'll need to improve on in the HSC.
Some hints:
For physics in year 12, keep all of your prac reports. You will be examined randomly on atleast one prac you do.
Ancient History, more of a focus on primary sources. You've learnt the basic stuff in Year 11, Year 12 from what I remember was rehashing that, but substantiating it with primary sources (so historians/pictures/reports from the era you're studying)
Rarely do schools make you do one lot of ancient societies in year 11 and then completely different ones in year 12.