1.4 Carbohydrates

Learning objectives

1.4A—Describe the structure and function of carbohydratesDescribe the structure and function of carbohydrates.• Monosaccharides (simple sugars) are the monomers for polysaccharides (complex carbohydrates). These monomers are connected by covalent bonds to form polymers such as complex carbohydrates, which may be linear or branched.- Exclusion: The molecular structure of specific carbohydrate polymers is beyond the scope of the AP Exam.

Monosaccharides are simple-sugar monomers. Cells connect monosaccharides with covalent bonds to form polysaccharides, or complex carbohydrates. A polysaccharide contains many connected monomers and can have an overall linear or branched organization.

Structural level	Description
Monosaccharide	One simple-sugar unit, such as glucose
Polysaccharide	Many monosaccharide units joined by covalent bonds
Linear polymer	Units form an overall unbranched chain
Branched polymer	The chain contains branch points

Illustrative carbohydrate	Representative biological function
Starch	Energy storage in plants
Glycogen	Energy storage in animals
Cellulose	Structural material in plant cell walls

When a prompt describes repeated sugar units joined into a large molecule, identify a polysaccharide. Then use evidence about storage, cell-wall structure, or branching to connect the general polymer organization with function rather than treating all carbohydrates as interchangeable sugars.

The molecular structures of specific carbohydrate polymers are explicitly outside AP Exam scope. Know the monomer–polymer relationship, covalent connection, linear or branched organization, and representative functions; do not infer a required detailed structural formula.

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