Scientists have a number of concerns regarding the GCSE
Some GCSE science questions do not require any understanding of science or how science works, a group of leading science bodies has warned.
The umbrella group Score said some questions could be taken as general knowledge, and the amount of maths covered was "woefully inadequate".
Science GCSE was re-launched in 2006 to make it more relevant to everyday life and encourage more pupils to take it.
Ministers said British pupils were the best in Europe at maths and science.
Score is an association of six scientific bodies, formed in 2006.
Its review of Science GCSE, sat in England, Wales and Northern Ireland, was to look at whether the new qualification was fit for purpose.
It looked at several areas: accurate science, how much mathematics was involved, the new "how science works" component, the types of questions and responses involved, and knowledge required.
It analysed 79 exam papers.
Score found some allowable answers which did not reflect correct science, and some indications that the mathematics required was "limited".
Its report says: "The full range of mathematics skills and techniques included within the specifications was not examined; the percentage of questions requiring mathematical knowledge was low."
Some awarding bodies awarded too many marks for "how science works", the scientists found, and on occasions these questions resembled general knowledge, they said.
GCSE science divided the science community when it was re-worked in 2006, with some thinking it was lowering the standard required and others praising the increased relevance to today's world.
In March this year, a report by the exams regulator Ofqual urged the government to take immediate action over falling standards in science GCSE.
It raised concerns about multiple choice answers, also picked up by the Score report.
Ministers in England said after the Ofqual report that they accepted there were problems with GCSE science.
Sir Alan Wilson, chair of Score, said: "Science is a quantitative subject yet the amount of maths in the exams varied widely and was generally woefully inadequate.
"There were also parts of some questions which did not require any knowledge of science or 'how science works' to answer them.
"While these general knowledge questions were not widespread, it is astonishing that there are any examples.
"The failings outlined in the report must now be addressed as we cannot afford to fail the young people who are working so hard to get their science qualifications.
"We must ensure that those qualifications are as robust as they can be."
Other members of Score include Sir Martin Taylor, vice-president of the Royal Society, who led the review.
He said: "Our future prosperity will depend on us producing generations of world leading scientists who will develop the technologies on which we can build a strong and resilient economy.
"That requires science education at all levels that is of the highest quality.
"If we have science exams that do not test the quality of mathematics needed to do good science or if we have questions that do not require scientific knowledge to answer them then we do not have an examination system that is fit for purpose."
A spokeswoman for England's Department for Children, Schools and Families said: "Our pupils are doing well in science, as shown by the results of the 2007 Timms study.
"Britain's young people came out top in Europe in maths and science, which is a tremendous achievement."
But she stressed the parallel efforts that were being put into the study of the three separate sciences - chemistry, biology and physics.
"We want to make sure we are doing all we can to stretch the best pupils who will be our scientists, engineers and innovators of the future.
"That is why we are introducing a range measures to attract more pupils into studying all three sciences, support teachers to deliver these specialist subjects and provide extra science prizes for the brightest pupils."
Most pupils do not study the separate sciences. In England they are entitled to be taught them - but schools are not obliged to offer them.