Are carbohydrates polysaccharides

Some are, some are not.

There are four kinds of carbohydrates, or sugars:

1. Monosaccharides consist of one molecule (examples include glucose, fructose, galactose, xylose, ribose, etc.)
2. Disaccharides consist of two molecules (examples include sucrose, lactose, maltose, etc.)
3. Oligosaccharides consist of a few molecules (examples include fructo-oligosaccharides, galactooligosaccharides, mannan oligosaccharides, etc.)
4. Polysaccharides consist of many molecules (examples include starch, glycogen, cellulose, pectins, etc.)