Structural features common to carbohydrates?

This question appears to be your typical high school Molecular Biology question from the questions at the end of the chapter.

Inorder to answer one must first understand some basics in approaching Bio and Molecular Chemistry.

1.  Know your steriochemistry i.e. Fischer projections.  To  accomplish this lets look at glyceraldehyde below in Fischer projection.

      H
       !
      C=O  (carbonyl group + H = aldehyde)
       !
 H--C--OH
       !
       CH2OH

So glyceraldehyde is an aldotriose i.e. aldehyde sugar.  Lets do another one say, dihydroxyacetone below.

CH2OH
 !
C=O  (carbonyl group with no H, so its a ketone)
 !
CH2OH

So, dihydroxyacetone is a ketotriose, a ketone sugar.

2. Sugars and starches are related in that a starch is a polysacharide i.e.many sugars linked together by unique glycosidic linkages.  So what is a glycosidic link?

The easiest way to answer this question is by drawing a diagram, which may be quite challenging in this format.
 
Lets take alpha maltose for example

(get your text book or other reference so you can see the ring structures and better visualize what I am telling you here. )              

The glycosidic linkage is represented by the oxygen O between the two ring structures.  Now the protocol for naming these little gems is to start counting on the ring from the carbon immediately to the right of the oxygen in the ring (not the oxygen between the two rings).  So maltose has the name 1,4 for the carbons connected by the glycosidic linkage.  Ah, but it does not end here since the hydroxyl group on carbon 1 can be either facing up over the ring (beta) or down under the ring (alpha).  So the complete name is alpha 1,4 maltose or beta 1,4 maltose.

Now, lets take a look at your homework.  

Starch has what common feature with the other sugars? Remember, to be a complex or compound sugar  (two or more sugars), they must be connected.  So what connects them, and that is the answer to what starch has in common with the others.

Glycogen, comes from glucose. Now you take it from here.

Sucrose is a compound sugar composed of fructose and what other sugar linked together?  Watch the glycosidic bond on this one as it employs all of the naming aspects stated above.

Maltose, did this one as the example.

Fructose, see glucose.

Xylose, it is an aldotriose; but count your carbons carefully.