AP Biology : Understanding Carbohydrates

Study concepts, example questions & explanations for AP Biology

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Example Questions

Example Question #31 : Macromolecules

The polymer chitin is made up of what carbohydrate momoner?

Possible Answers:

Glucopyranose

N-Acetylneuraminic acid

Glucose

N-Acetylglucosamine

Fructose

Correct answer:

N-Acetylglucosamine

Explanation:

Chitin is a polymer that makes up the cell wall of fungal cells as well as the exoskeleton of arthropods. It itself is made up of N-Acetylglucosamine

Example Question #31 : Macromolecules

Which of the following is a polysaccharide stored in plants?

Possible Answers:

glycogen

starch

glucose

lipids

Correct answer:

starch

Explanation:

Starch is a polysaccharide stored in plants.  Glycogen is a polymer of glucose in animals stored in the liver and muscle cells.  Lipids are molecules made mostly of carbon and hydrogen that store energy.

Example Question #31 : Understanding Carbohydrates

Which of the following is a monosaccharide?

Possible Answers:

Lactose

Fructose

Lactase

Sucrose

Maltose

Correct answer:

Fructose

Explanation:

Sucrose is made up of a glucose molecule and a fructose molecule. Knowing this gives a hint to the correct answer. Maltose is made up of two glucose molecules. Many glucose molecules joined together make up starch. Lactose is the sugar found in milk, and is made up on a glucose and a galactose molecule. Thus, all of the other sugars listed are disaccharides. Lactase is an enzyme, as shown by the "-ase" ending. 

Example Question #32 : Understanding Carbohydrates

Monomers of sugars form disaccharides and polysaccharides via what type of bonding?

Possible Answers:

Glycosidic linkage

Phosphodiester bond

Ester linkage

Peptide bond

Hydrogen bond

Correct answer:

Glycosidic linkage

Explanation:

A phosphodiester bond occurs in DNA and RNA between nucleotides to form nucleic acids. Ester linkage occurs in fats and lipids between a carboxyl group and the carbon chain. A peptide bond occurs between two amino acids to form a peptide bond. Hydrogen bonding is the interaction of a hydrogen of one molecule with either a oxygen, nitrogen, or fluorine of another molecule.

Example Question #33 : Understanding Carbohydrates

A maltose molecule can be broken down into two molecules of glucose via what reaction?

Possible Answers:

Hydrolysis

Condensation

Dehydration

Polymerization

Hydration

Correct answer:

Hydrolysis

Explanation:

Maltose is a disaccharide and glucose is a monosaccharide so the question is asking what will break the disaccharide into its respected monosaccharide. Hydrolysis is the addition of a water molecule to break the glycosidic linkage of a sugar. Dehydration reaction is a type of condensation reaction that will ultimately join two monosaccharides together via the removal of a water molecule. Polymerization is a general term with regards of monomers forming polymers through a reaction. Hydration reactions are the addition of a water molecule but do not necessarily break any bonds but are used form an alcohol.

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