Biology, chemistry and physics may be taught as separate subjects leading to three separate GCSEs. Another approach is to teach integrated science (biology, physics and chemistry, plus a bit of geology and astronomy); integrated science can be taken as either a single or a double GCSE, though few independent schools offer the single.
Plainly the two different systems suit different children. Those wanting to take a science A-level will usually need either the relevant single-subject GCSE or the double award integrated science GCSE and both systems are widely available in independent schools. There is also a GCSE in ‘scientific literacy for the 21st-century’, which covers issues including global warming and mobile phone technology and which will not be adequate for A-level study. Curricular debate and development continues.