Proposals to mark GCSE students on their spelling and grammar and to scrap re-sits were published by England's exams regulator today.
Ofqual has launched a consultation on the plans, which are the latest step in the Government's plans for a major overhaul of GCSEs.
Under the proposals, from 2012 teenagers will have to sit all GCSE exams in the summer at the end of the two-year courses.
The move effectively scraps the current system, which splits GCSEs into "bitesize" units, with students assessed on these throughout the course.
Pupils will also no longer be able to re-sit exams in order to boost their marks. The only exception to this would be English and maths.
The consultation sets out plans to allow students who need these qualifications to take them in November, so that they do not have to wait 12 months for another opportunity.
The reforms, intended to toughen up GCSE exams, were first announced by Education Secretary Michael Gove last year and included in the Department for Education's White Paper.
Speaking in the summer, Mr Gove attacked the "culture of resits" that had resulted from allowing students to keep taking modules until they achieved the desired grade.
He told BBC1's Andrew Marr Show: "The problem that we had is that instead of sitting every part of a GCSE at the end of a course, bits of it were taken along the way.
"Those bits could be resat. That meant instead of concentrating on teaching and learning, you had people who were being trained again and again to clear the hurdle of the examination along the way.
"I think it's a mistake and I think the culture of resits is wrong. I think that what we need to do is make sure, certainly at GCSE, that you have a clear two-year run."
The reforms will also see students marked on their spelling, punctuation and grammar.
This will only apply to English literature, geography, history and religious studies to start with.
Ofqual's consultation sets out plans to allocate five per cent of a GCSE qualification's total marks to spelling, punctuation and grammar.
It includes assessing pupils on their accuracy, use of specialist terms and the rules of grammar.
Ofqual said the consultation on the changes will run until November 4. Officials added that they were particularly keen to hear from teachers.