Every A-Level paper is marked against assessment objectives rather than against a list of facts. AO1 rewards knowledge and understanding, AO2 rewards applying it to the specific context in the question, and AO3 rewards analysis and evaluation. The weighting between them varies by subject and by paper, and it is published in the specification. Most lost marks are AO2 and AO3 marks: the candidate knew the content and answered in general terms rather than about the case, the source, or the data actually given.