Exam setters have warned geography teachers not to "cherry pick" syllabus topics after an investigation into this summer's GCSE found some pupils appeared not to have studied all subject areas.
Schools had complained that the exam was particularly hard, but the OCR board said that could be because some topics, such as trade and meteorology, were not being fully covered.
Teachers suggested there were too many questions on subjects they thought were marginal, making it difficult for pupils who had revised "mainstream" subjects.
OCR's geography chief examiner conceded the balance of the exam's content may not have been "ideal". However, he said: "Trade and meteorology do not appear to be popular, but they are on the specification (of what should be taught) and teachers must be careful that they don't 'cherry pick' from the content to suit their own preferences."
"Having said this, we want to make the candidates' examination experience a positive one and perhaps the balance of the content in the papers was not ideal this time around."
The GCSE also appeared more difficult because teachers were entering less able candidates for the higher paper, the chief examiner concluded. The report on the higher paper acknowledged the comments about challenging questions, but said: "Overall, the feedback from examiners has been unanimous in stating that the paper was at an appropriate level of difficulty for the majority of candidates."
In coursework, the principal moderator praised much "excellent work" in geographical investigations. "Many are a joy to read and are beautifully presented and communicated using ICT skills of the highest order.
Phenomenal strides have been taken ... over the past few years. For this, everyone involved deserves praise."