Monosaccharides  are  the  simplest
   carbohydrates.
<P>
   Aldoses and ketoses are structural isomers.
<BR><LI> Aldoses have a carbonyl at the end of the carbon skeleton.
<BR><LI> Ketoses have the carbonyl within the skeleton.
<P>
   Glucose and galactose each has an asymmetric carbon and are
<BR><LI>
	  + stereo isomers.