Sometimes, Yes? but to what extent, I am not sure. If you want a remark because you genuinely feel you have underachieved a grade after working very hard, Get your paper back to see where you went wrong.
For chemistry I can't really see how there would be a very big distribution of mistakes as the mark scheme is very procise.
Biology is is more of suggest type questions, so i would assume biology has more margin of examiner error or marking mistake.
But is it work a remark if you completely balls'd it up? The chances are you will only potentially go up a few UMS, maybe a grade(realisticly). Unless you absolutely feel you nailed the exam.