SAT II Biology M : Carbohydrates

Study concepts, example questions & explanations for SAT II Biology M

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Example Questions

Example Question #1 : Macromolecules

Carbohydrates represent important macromolecules in the biochemical pathways of many organisms. 

Which of the following is/are monosaccharide(s)?

I. Glucose
II. Fructose
III. Maltose

Possible Answers:

I, II, and III

I and II

II and III

I only

I and III

Correct answer:

I and II

Explanation:

Glucose and fructose are monomeric saccharides, or monosaccharides. The carbon to hydrogen to oxygen  ratio exists in a 1:2:1 pattern indicative of a monomeric saccharide. The molecular formula of glucose and fructose is . Maltose is a disaccharide composed of two molecules of glucose.

Example Question #1 : Macromolecules

Disaccharides, such as maltose, are produced when two monosaccharides undergo a dehydration synthesis reaction.

Which of the following formulas represents a disaccharide?

Possible Answers:

Correct answer:

Explanation:

The disaccharide maltose is formed by the dehydration synthesis reaction of two glucose monomers. When simply adding the two glucose monomers together, it may be thought that the summation of the two  will be the chemical formula of maltose. However, this does not account for the dehydration synthesis reaction in which one oxygen atom and two hydrogen atoms disappear. After accounting for these molecules the chemical formula for maltose will be represented by .

Example Question #2 : Macromolecules

Polysaccharides are considered sugar moieties that include 3 or more monomeric saccharides together.

Which of the following is/are polysaccharide(s)?

I. Glycogen
II. Starch
III. Cellulose

Possible Answers:

I, II, and III

I and III

I and II

I only

II and III

Correct answer:

I, II, and III

Explanation:

Glycogen, starch, and cellulose are all polysaccharides composed of many glucose monomers linked together.

Example Question #2 : Macromolecules

Animals and plants store glucose in saccharide polymers. 

Which of the following is the polymer form of storage in plants and animals, respectively?

Possible Answers:

Plants: cellulose

Animals: glucose

Plants: sucrose

Animals: maltose

Plants: starch

Animals: glycogen

Plants: glycogen

Animals: glycogen

Plants: chitin

Animals: glycerol

Correct answer:

Plants: starch

Animals: glycogen

Explanation:

The sugar polymer form in which plants store energy is starch, whereas with animals, it is glycogen. While the other answers may in fact be sugar molecules involved in energy metabolism, they do not represent the primary sugar polymer storage molecule. Therefore the correct form of storage for plants is starch. And the correct form of storage for animals is glycogen.

Example Question #3 : Macromolecules

In which of the following molecular forms do animals store energy?

Possible Answers:

Lipids and glycogen

Lipids only

Glycogen only

Peptidoglycan only

Glycogen and peptidoglycan

Correct answer:

Lipids and glycogen

Explanation:

Both lipids (fat) and glycogen (made up of glucose molecules) store energy in animals. Lipids are used for long-term energy storage while glycogen, found in the liver and muscles, is used for short-term energy storage. Peptidoglycan is the molecule that makes up the bacterial cell walls.

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