Yes, they do. For your universtities they need an indication from your AS grades ofc they look at them, how else do they consider your place they can't tell the future. But they can roughly assume what you "may" get in A2 if you get a D at AS in maths for example and they want a A overall, it doesn't seem like you can get it if AS is much easier and say you can get that A.
Focus on these, don't be a fool and not revise for them cause you cba.
We all are scared, but if you revise for them well enough there's no reason to be.
My 2 cents for u