I know exactly what you're talking about, holl. I received an additional four marks over my raw assessment mark, but I think it would have been a lot more had my class bothered to complete assessments, attend class, or complete set homework and exams. Most decided to walk out during the CSSA Trials and I had seen a few walk out of the HSC Exams, if I'm not mistaken.
Our average at school had been below 50, which is very disappointing to see - in any course (I think our average was less than 50, in terms of assessment marks alone, in Chemistry as well). I figure, like you, that if my classmates had given it a fair go, our marks would have been a lot better as a group, rather than on an individual basis.
I was the 'most enthusiastic' about our exams and the subject throughout the year (as had been the case in previous years, Years 9-10 Computing Studies and Year 11 Preliminary IPT). Being the only one who cares, to use your words, is very disappointing in a class where 95% of your classmates don't listen, don't do what they're told and generally run riot.
I'm not entirely pleased with my marks, as you no doubt would have known by now, but there's nothing else I can do to change anything. My teacher would have been a little disappointed in my final HSC mark, but I suppose it is an expected minimum mark, from my perspective (as top student in IPT, two years running).