Carbohydrates
Carbohydrates are energy-storing molecules like sugars and are used in cellular respiration to produce energy (via reactions that break high-energy bonds).
Monosaccharides
Monosaccharides (monomers) like glucose or fructose are simple sugars comprised of hydrogen, oxygen, and carbon.
Polysaccharides
Polysaccharides (polymers) are formed when multiple monosaccharides chain together and are used for more extensive energy storage as well as structural purposes (i.e. cellulose in plant cells).
Much of the reactions concerning polymer synthesis are dehydration reactions (they release water).