An AS-level biology exam sat by pupils in England, Wales and Northern Ireland last month contained a mistake, it has been revealed.
The exam paper was set by Edexcel and was worth one mark out of a possible 425, the BBC reports.
However, the exam board has reassured students that no one will be disadvantaged by the blunder.
"The marks for this paper will be adjusted during marking and standardising to ensure no candidate is disadvantaged and full details about how this was dealt with will be published in the mark scheme and examiner's report," Edexcel said in a statement.
However, one student wrote to the BBC expressing concern over the length of time wasted trying to figure out the solution to the question.
This come just days after it emerged that an AS-level business studies exam set by the Assessment and Qualifications Alliance contained an 'impossible question'.
Posted by Katy Kearns