Several options exist for science at GCSE, depending upon the school. GCSE Science and GCSE Additional Science cover Physics, Chemistry and Biology. Students may also take individual science subjects. For example single subject GCSE Chemistry incorporates all the Chemistry material in GCSE Science and Additional Science, together with extension modules.
I teach Chemistry and Physics for all of these GCSEs. I don’t teach Biology, though this typically seems to be the component of the Science and Additional Science GCSEs with which students have least difficulty.