Heteropolysaccharides are complex carbohydrates composed of different types of monosaccharide units. They play various structural and functional roles in living organisms. Among the given options, heparin, peptidoglycan, and chondroitin sulfate are heteropolysaccharides.

Heparin:
- Heparin is a highly sulfated heteropolysaccharide that is primarily found in the granules of mast cells and basophils.
- It consists of repeating disaccharide units composed of glucuronic acid and N-acetylglucosamine.
- The glucuronic acid residue is sulfated at various positions, giving heparin its negatively charged nature.
- Heparin is known for its anticoagulant properties and is commonly used as a medication to prevent blood clotting.

Peptidoglycan:
- Peptidoglycan is a major component of bacterial cell walls and is found in both Gram-positive and Gram-negative bacteria.
- It is composed of repeating disaccharide units called N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM).
- These disaccharide units are linked through β-1,4-glycosidic bonds.
- The NAM residues are cross-linked by short peptide chains, forming a mesh-like structure that provides rigidity and shape to the bacterial cell wall.

Chondroitin Sulfate:
- Chondroitin sulfate is a sulfated heteropolysaccharide mainly found in the extracellular matrix of connective tissues, such as cartilage, bone, and skin.
- It is composed of repeating disaccharide units consisting of N-acetylgalactosamine (GalNAc) and glucuronic acid.
- The disaccharide units are sulfated at various positions, giving chondroitin sulfate its negative charge.
- Chondroitin sulfate provides structural support and elasticity to tissues, and it is often used as a dietary supplement for joint health.

Cellobiose:
- Cellobiose is a disaccharide composed of two glucose units linked by a β-1,4-glycosidic bond.
- It is not a heteropolysaccharide as it consists of identical monosaccharide units (glucose).
- Cellobiose is a common product of cellulose degradation and serves as an intermediate in the breakdown of cellulose by cellulase enzymes.

In summary, heparin, peptidoglycan, and chondroitin sulfate are heteropolysaccharides, whereas cellobiose is a disaccharide composed of identical monosaccharide units.