Radical changes to GCSE and A-level exams are to be introduced so that even essay-dominated subjects will be marked electronically, the man in charge of the "modernisation" of England's exams system has said.
Papers for subjects such as English and history will be scanned electronically and examiners will then mark individual questions, rather than whole scripts.
Critics, who include leading independent school heads, fear that the changes will lead to the dumbing down of exams and therefore of teaching.
Writing in this week's TES, Cynthia Hall, president of the Girls' Schools Association, says there is a danger of downgrading examining to "a multiple-choice exercise that could be done by the proverbial monkey".
The changes mean that electronic marking, being trialled at the Edexcel exam board, will be dramatically extended and many more papers will be marked by unqualified undergraduates rather than teachers.
The plans were revealed by Jonathan Ford, managing director of the new National Assessment Agency, at a meeting of private-school headteachers last month, and will be hugely contentious.
A chief examiner for one of Edexcel's rivals said: "The concern is that this represents a dumbing down of the examination process. That the boards could say, 'we want more multi-choice type question and answers'."
The assessment agency believes the moves will help improve accuracy, partly because the use of technology will allow questions to be marked more than once, and help it address chronic shortages of examiners.
It also believes that with component marking where examiners mark individual questions, rather than whole scripts, the grading process will be more accurate, as examiners focus on tightly-defined mark schemes.
But headteachers who attended the joint GSAHeadmasters' and Headmistresses' Conference meeting where the comments were made, are worried.
In her article, Ms Hall says examiners needed to be able to see whole scripts to get a proper feel for candidates' work.
There are serious worries, she argues, that the demands of the marking process will drive the content of exams, leading to a greater focus on short answers in traditionally essay-dominated subjects.
"My fear is that lower-order assessment will necessitate lower-order questions and that lower-order teaching will follow.
"We need to develop the professionalism of our teacher examiners, not downgrade the job."
Martin Stephen, HMC chairman, said: "This is the tail wagging the dog. It appears the examination system is being designed for the convenience of marking, rather than addressing the need to assess higher-order skills, such as extended argument."
Edexcel and the NAA emphatically deny that there will be any "dumbing down", arguing that exams should be designed around pupils' assessment needs. Short answers are not currently widespread in English and history.
In this summer's e-marking trial by Edexcel more than a million GCSE and A-level scripts were scanned and marked question by question by examiners at computer screens. But English was not included in the trial.
A spokesman for the assessment agency, a branch of the Qualifications and Curriculum Authority set up to lead the pound;140 million modernisation of the exams system, said there would be no "dumbing down".
"There's no question of papers being designed to make marking easier. It has always been the intention to trial digital scanning and component marking in subjects where it is feasible," he said.
"Component marking allows complex questions to be sent to the most experienced and knowledgeable senior markers. It also allows questions with straightforward right and wrong answers to be dealt with by more junior markers. This increases the speed of processing and the accuracy of marking."
In Edexcel's trial, undergraduates working in dedicated centres, marked short questions in eight GCSE and GNVQ subjects this year, including maths, science, French and Spanish. English GCSEs were also marked electronically, but the subject was not part of the short-answer experiment. The board views the scheme as a great success.
Other boards have used students in recent years for conventional marking and say this has been successful. Mike Tomlinson, the former chief inspector of schools who investigated 2002's A-level regrading crisis, has backed the use of non-teacher examiners.