2007 AQA Biology GCSE (3 modular tests, spread out over 12 months so you only need to revise a few topics at a time) 28 marks out of 45 (62%) on the first paper gets you an A* Grade. Subsequent papers are expected to be graded on the same basis.
1982 JMB Biology O Level Paper (Exams cover all of two year syllabus) 80.1% required for a Grade A, according to the examiners report.
Dumbing down? No, no, no. The pupils are just getting cleverer.
The two kids that I feel sorry for are:
1) The highly intelligent pupil who has worked hard and would always have answered 95% of the questions correctly. They receive no real recognition of their talent.
2) The kid who scrapes a 'C' Grade and is told how clever they are. They are encouraged to study the subject further and later discover after wasting much time and effort that they have no real academic ability whatsoever. They have been completely conned.
Oh, for non teachers- A* is the grade above A nowadays (Don't ask me why)