The A-level exam has become "hollow preparation" for university, by undermining independent study and original thought, says a think tank.
The Reform group claims exam modules have created a "learn and forget culture" - which it likens to using a sat-nav rather than map-reading skills.
It says universities should ensure the quality of A-levels, taken by pupils in England, Wales and Northern Ireland.
Ministers said the extended project and the new A* would address concerns.
The Reform report analysed the views of academics in English, mathematics, chemistry and history.
Researchers said academics reported today's students as having inferior reasoning skills to those who started courses in the 1990s.
They complained of "high maintenance" students who sought constant advice.
Dr Dewi Lewis, chemistry admissions tutor at University College London, said frequent assessment favoured the "shallow learner".
"Candidates are led through the exam in a sort of quiz or puzzle style, with lots of opportunities to jog their memory," he told Reform.
Professor Bailey, professor of statistics at Queen Mary, London University, told Reform researchers: "The most important change in exams over the period 1951-2008 is that sitting a mathematics A-level paper now is more like using a sat-nav system than reading a map.
"If you read a map to get from A to B, you remember the route and learn about other things on the way. If you use a sat-nav, you do neither of those things.
"The questions in the 2008 paper are heavily structured in this way and the result is that students will retain very little knowledge and develop very little understanding."
Prof Bailey also said today's students were given hints and instructions on exam papers.
The Reform report criticised the introduction of modular A-levels, saying this had broken up the coherence of a course - "limiting the ability of teachers to ensure a thorough understanding of the subject".
"The ability to resit reinforces the mindset that success at A-level is actually about a narrow achievement in six separate mini-courses," the report said.
The think tank concluded that universities should resume control of public exams, "restoring their intellectual rigour".
"Historically universities have played a key role in upholding exam standards; in the first half of the 20th Century they took a leading role in setting school examinations," the report said.
"This link has become weaker over time, with academics giving way to teachers and playing a progressively reduced role in the exam setting process."
Elizabeth Truss, deputy director of Reform, said today's students were being badly let down by the A-level system.
"They are not developing what they really need: A spirit of independent enquiry and confidence that will set them up for university and later life," she said.
Director general of the Russell Group, which represents top universities, Dr Wendy Piatt, said: "Russell Group universities take a keen interest in ensuring that UK qualifications are sufficiently robust and academically challenging so that students have the skills and knowledge to benefit most effectively from our courses.
"We are therefore willing to consider any way we can contribute to improving the means by which students are taught and assessed."
Iain Wright, the minister with responsibility for reform for 14 to 19-year-olds, said: "The changes we are making to A-levels ensure that A-level papers contain more open-ended questions, requiring greater thought and more detailed written replies.
"We are introducing new extended projects, which will encourage independent research, planning and study skills - exactly the sort of skills needed at university.
"The new A* will also encourage the best students to demonstrate the upper limits of their ability."