Blood is an aqueous solution and will easily dissolve polar, hydrophilic molecules. Nonpolar molecules, however, do not easily exist in this solution and require a bound polar group, such as a carrier protein, to exist in equilibrium.

Proteins, carbohydrates, and nucleic acids all contain polar groups, allowing them to dissolve in the blood. Lipids, however, are nonpolar and require transport proteins. Steroids are a class of lipids and will require protein assistance for transport in the blood.

Sucrose is a carbohydrate, glycine is a polar amino acid, and ATP is a polar nucleic acid derivative.

Amphipathic molecules contain both polar and nonpolar regions, making them an extremely diverse class with an array of functions. For example, bile is an amphipathic molecule whose nonpolar region interacts with fats and whose polar region interacts with the aqueous environment of the small intestine.

Most lipids are entirely nonpolar and hydrophobic. Phospholipids, however, are formed from a glycerol molecule bound to two hydrophobic fatty acid tails and a hydrophilic phosphate head. This structure allows phospholipids amphipathic properties. Most notably, phospholipids are able to interact with the aqueous environments in the cell cytosol and extracellular environment, while maintaining the hydrophobic region of the cell membrane that acts as a semipermeable barrier.

Triglycerides are considered nonpolar. Glutamate is an acidic amino acid with highly polar properties. Maltose is a six-carbon sugar (carbohydrate) and is highly polar.

Lipids have a variety of functions in the human body, one of which is the storage of energy for later use. This function is accomplished by triglycerides (also called triacylglycerols), which belong to the class of glycerolipids.

Fatty acids synthesized in the human body always have an even number of carbon atoms usually between 12 and 28. Odd-numbered fatty acid chains will occasionally be found in plants and marine animals.

A phospholipid is made up of two fatty acids and a phosphate group with an R-group attached to a glycerol backbone. The phosphate group allows for one end of the molecule to be polar while the fatty acids allow for the other part to be nonpolar. Phospholipids are a major component of the bilayered cellular membrane 

Carbohydrate monomers (monosaccharides) can be joined together with either alpha or beta linkages. Humans have the enzymes necessary in order to break down alpha linkages, but not beta linkages. Cellulose is a polysaccharide in which the monomers joined together by beta linkages, so humans cannot digest cellulose. Some bacterial species are capable of cleaving these linkages and have developed symbiotic or mutualistic relationships with animals. These bacterial species inhabit the mammalian digestive tract, cleaving beta linkages and gaining protection from the outside environment.

The size and branching pattern of a carbohydrate do not affect its ability to be digested.

The two most common polysaccharides found in plant cells are starch and cellulose. Starch is the primary source of energy storage, while cellulose is used to construct the plant's cell walls.

When a monosaccharide becomes cyclic in form, the anomeric carbon can have its hydroxyl group pointing in the same direction as the methoxy group, or oriented in the opposite direction. This orientation determines whether the sugar is considered alpha or beta.

Carbohydrates are linked together to form disaccharides and other polysaccharides through glycosidic linkages. A glycosidic linkage is one in where two sugar molecules are bridged by an oxygen atom. Peptide linkages are found between amino acids and phosphodiester bonds are found between nucleic acid monomers. Ionic bonds involve the complete transfer of one or more electrons from one species to another. Hydrogen bonds are weak intermolecular and intramolecular forces that contribute to the stability of many substances such as liquid water.

Glycogen and starch molecules are connected by alpha linkages. Glycogen and starch can be digested by humans because we have an enzyme capable of separating these linkages to produce monosaccharides. Cellulose on the other hand is connected through beta linkages. These beta linkages allow for the polysaccharide to form straight chains which can serve structural purposes such as plant cell walls. Cellulose, however, cannot be digested by humans because we do not have enzymes capable of severing these linkages.