To gain the maths GCSE, students have to sit seven tests and submit one piece of coursework
Edexcel spokesman
It was possible to gain an A grade with a score of just 47 per cent in one of this year's GCSE exam papers, it has been revealed.
The Times Educational Supplement reported that in one Edexcel maths paper, worth a quarter of the overall marks, a grade C required just 16 per cent.
And an AQA business studies paper saw the A grade set at 47 per cent.
In total there were more than a hundred papers where it was possible to gain good GCSE grades with scores as low as 45 per cent.
Edexcel defended the grading, saying that students "have to perform consistently across all stages to gain the grade".
A spokesman added: "Edexcel's chief examiners and accountable officer are confident that the grade boundaries set this year are commensurate with boundaries from past years.
"To gain the maths GCSE, students have to sit seven tests and submit one piece of coursework.
"The marks referred to by the TES relate to the higher-tier paper and just one of seven stages.
"It does not mean that you can gain a GCSE grade C on one test's marks."
A spokesman for AQA added that the lower boundaries for some grades were required because it "became apparent that candidates had consistently found elements of this year's paper more difficult than last year's paper".
"We have to take that into account and adjust that in order to maintain the standard," he added.
However, Alan Smithers, director of education and employment research at the University of Buckingham, told the Times that the marks showed grades were "downright misleading".
"Grades are to summarise a pupil's achievements for the next stage of education and employment," he added.
"If we're giving such misleading messages, it's no wonder that teachers and employers are expressing concern."

Dods Parliamentary Communications Ltd