The "value and credibility" of the new national curriculum will be undermined by the rapid expansion of academies and free schools, leading figures in science education have warned.
Standards are at risk because of the freedoms being handed to schools, with the danger that science lessons could be skewed by groups that hold "particular beliefs".
Rigorous inspections of lessons in academies and free schools will be needed to ensure high-quality provision, according to the Association for Science Education, the Institute of Physics, the Royal Society, the Royal Society of Chemistry and the Society of Biology.
"It is worrying that the academies and the new free schools will not have to follow the national curriculum," the associations, which work in partnership as Score (Science Community Representing Education), wrote in evidence to the national curriculum review.
"The curriculum cannot claim to be truly 'national' if different types of schools are to be under varying obligations.
"When the national curriculum was introduced, it applied to 93 per cent of students in the maintained sector. Today, the rapid growth in academies, and possibly free schools, means that within a few years, a substantial proportion of five to 16-year-olds are likely to sit outside the national curriculum." This undermines its "perceived value and credibility", the submission said.
Score chair Graham Hutchings said the growth in academies and free schools, meant "large numbers" of pupils might not be offered the national curriculum, which is due to be introduced from 2014.
"I'm sure that's not what the Government wants, and newly independent schools might well follow the national curriculum, but we don't know that yet," said Professor Hutchings, who lectures in physical chemistry at Cardiff University.
Annette Smith, chief executive of the Association for Science Education, said there was concern that growing numbers of pupils would lose the "entitlement" of the national curriculum.
She also said that groups with particular religious beliefs might use their exemption from the national curriculum to skew what they teach.
"We are concerned that if people want to set up academies and free schools on account of particular and single-issue beliefs, they can do so without constraint," she told The TES.
"Inspections must make sure schools are not using these freedoms to the detriment of young people."
The warning follows an application for a free school to be run by the Everyday Champions Church in Newark, Notts, which said it wanted to teach creationism across the curriculum. Education secretary Michael Gove has said that the Government would consider free school applications from creationist groups.
A spokesman for the Department for Education said it trusted teachers to use their expertise to do the best for pupils.
"Academies must provide a broad and balanced curriculum and they are inspected by Ofsted to ensure that standards are high," he said.
"Science will remain as a compulsory part of the new national curriculum, which will form a national benchmark of excellence for all schools - including academies.
"Science is a key part of the new English Baccalaureate, which will make sure that all children can access the core academic subjects."
ON TRACK FOR 2012
Education secretary Michael Gove announced his intention to review the national curriculum for five to 16 year-olds in January. An advisory committee will "guide" the review and an expert panel will also help to find evidence and contribute towards its content.
The first phase will develop new programmes of study for English, maths, science and PE. Ministers will consider the proposals at the end of this year and the public will be consulted during 2012. The new curriculum will be taught from September 2013.