I've just started my AS-levels, I do: biology, chemistry, maths and further maths.
I can assure you maths will be very beneficial to take.
The new science AS-levels are far more mathematical in terms of assessment (20% of marks per paper in chemistry, 10% for biology) and there is FAR more maths skills needed for the type of maths usually associated with that science at the KS5 stage.
Take biology for example (in all honesty the best example):
There is a helluva lot more maths in biology now (I think). For small scale biology (biochemistry, cells etc), simple worded equations are present in year 12 and algebraic equations (I think only 1 though) in year 13. For medium scale biology (organs etc) say hello to worded equations and some geometry. Last but FAR from least, comes large scale biology (biodiversity, evolution etc)...expect worded equations and more importantly several statistical equations and the standard type of data distribution:
- standard deviation (covered in S1 for maths)
- understanding the normal distribution (S1)
- student's t test (S3 although you can live without S3)
- correlation coefficient (same as previous)
- chi - squared test (A2 only) (same as previous).
^ these all assume Edexcel maths spec is used and OCR spec is used for science.
I personally think when it comes to maths OCR B chemistry (what I do) is disappointing compared to the challenges (sorry I love maths) they give you in OCR A biology. In chemistry just say hello to simple algebraic equations you may have covered at GCSE and geometry...
Unfortunately for some, biology and chemistry are becoming more mathematical...universities need people to have the right skills...if you want to do these subjects you will need to adapt.
Just remember the Student Room is here to help.