Re: how do the ratios of hydrogen to oxygen atoms compare in fructose and glucose

Both fructose and glucose have the same molecular formula:
C6H12O6

So they are both sugars composed of 6 Carbon atoms. A sugar with 6 
Carbon atoms is referred to as a "hexose". They both have a ratio of 12 
Hydrogen atoms to 6 Oxygen atoms.

So, the ratios of hydrogen to oxygen atoms in fructose and glucose are the 
same:  2 atoms of hydrogen to 1 atom of oxygen.

The difference between glucose and fructose is in their structures - 
hexagon vs pentagon - which might best be seen with a diagram.

This diagram is from this webpage, which you might want to visit for   
more information on this topic:

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Carbohydrates.
html



Notice that glucose has it's 6 carbon atoms arranged in a hexagonal 
(six-sided) ring, but that one of the 6 points of the ring is occupied by an 
oxygen atom . There is a CH2OH group linked to a carbon 
atom near the oxygen atom in the ring.

Fructose has a pentagon shape, similarly having one of the 5 points 
occupied by an oxygen atom. There are two CH2OH groups 
linked to  the carbon atoms nearest that oxygen atom in the ring.