Since 1988, there has been a trend towards combining physics, chemistry and biology into one course of science - an approach adopted by the national curriculum. This is partly an attempt to break down gender divides, and prevent girls from opting out of physics and chemistry at an early age.

But this year has seen a reversal of the trend, with the numbers for separate subjects rising. The number of pupils taking chemistry went up by 6.9 per cent, biology by 5.9 per cent and physics by 6.1 per cent.

The Association for Science Education believes that this may be the result of schools allotting more than 20 per cent of the curriculum time to science and allowing bright pupils to take the subjects separately. This is possible thanks to the slimmed down national curriculum introduced by Sir Ron Dearing.

There has been pressure from academic schools, particularly in the independent sector, for keeping separate sciences. They believe the separate courses are a better preparation for A-level science.

The ASE said that, while it was in favour of combined science, the uptake in single sciences is not yet a cause for concern because all three subjects have risen equally. Moreover, combined science, which is numerically more significant, continued to rise. Only 46,446 pupils took single physics this year compared with 997,422 pupils taking combined science. Overall the science entry rose by 2.1 per cent.

Jane Wheatley, chair of the ASE, said: “What we are against is girls dropping physics and chemistry. There would be disquiet if the previous gender biases re-emerged.”