Pupils took to social media on Tuesday expressing their confusion after what appeared to be a business studies question featured in a biology exam paper.
A question in the AQA Biology exam reportedly asked pupils to define an "independent company", with streams of children later complaining about the 'unfair' question on Twitter.
Within hours of pupils completing the exam, more than 100,000 tweets about it were sent, but the exam board insists there was no mistake in the question's inclusion.
Jack Green, 16, a pupil at South Hunsley School in North Ferriby, East Yorkshire, said pupils were "worried" about their grades as they thought the exam was markedly different to the syllabus they had been taught in class.
As well as the 'independent company' question, Jack said there was also a question about 15-year-olds' favourite alcoholic drink.
An AQA spokeswoman said that the 'independent company' question was one of several on the subject of drug trials, and that the underage drinking question was in a section on alcohol abuse.
The exam board said that both questions were included on the syllabus.