The exam board Edexcel took the action after an investigation revealed that the student, who has not been named, plagiarised three-quarters of his or her assignment from the internet.
The student lifted an essay - "Memory: how do we remember what we know?" - direct from the website of the Centre for the Study of Intelligence, a part of the US Central Intelligence Agency. A second essay, also on memory, was taken from Ohio state university's psychology department's website.
The student, from a school in Wales, has been disqualified from one unit of the qualification. But the board decided not to bar them from re-sitting the unit, even though the extent of the plagiarism was sufficient to warrant disqualification from the whole exam.
An Edexcel spokesperson said: "These two plagiarised parts represent the bulk of the candidate's coursework and is clearly not work for which they can receive any personal credit.
"The candidate has been warned that any repetition would undoubtedly result in total disqualification and future debarment from entry to any Edexcel examination."
As The TES has reported, tens of thousands of essays are now available on the internet, through sites such as Study-Area.com and CourseworkHelp.co.uk.
However, it's not so simple to cheat. Several teachers have said that fraudulent work is relatively easy to spot because it often tends not to read like anything the pupil has written before.