Question 1

Which of the following enzymes catalyzes the hydrolysis of a- glycosidic linkages in starch?

Accepted Answer

A)   phosphorylase
B)   glycolase
C)   amylase C

Question 2

Enzymes that readily break starch apart cannot hydrolyze the glycosidic linkages found in cellulose. Why is this logical?

Accepted Answer

A)   Cellulose molecules are highly branched, and enzymes are too bulky to fit.
B)   Starch is held together by peptide bonds, not glycosidic linkages.
C)   The geometry of the bonds is different, and the shapes of enzyme active sites are highly specific.
D)   Starch is held together by hydrogen bonding, not covalent bonding. C

Question 3

How do the a and fi forms of glucose differ?

Accepted Answer

A)   Their linear structures differ in the location of a hydroxyl group.
B)   The oxygen atom inside the ring is located in a different position.
C)   Their ring structures differ in the location of a hydroxyl group.
D)   The a form can be involved in 1,4 and 1,6 glycosidic linkages; the fi form can participate only in 1,4 linkages. C

Question 4

Which of the following polysaccharides is made up of parallel strands joined together by hydrogen bonds?

Accepted Answer

A)   peptidoglycan
B)   glycogen
C)   chitin
D)   starch

Question 5

Which of the following carbohydrates contains a peptide bond?

Accepted Answer

A)   cellulose
B)   Carbohydrates don't contain peptide bonds; only proteins do.
C)   chitin
D)   peptidoglycan
E)   glycogen

Question 6

Which of the following enzymes catalyzes the hydrolysis of a- glycosidic linkages in glycogen?

Accepted Answer

A)   glycolase
B)   phosphorylase
C)   amylase

Question 7

Which of these best reflects the following relationship: monosaccharide versus polysaccharide?

Accepted Answer

A)   glucose versus glycogen
B)   a- linkage versus fi- linkage
C)   glucose versus fructose
D)   1,4- glycosidic linkage versus 1,6- glycosidic linkage

Question 8

Which of the following molecules would you expect to have the most free energy per gram?

Accepted Answer

A)   one with hydrogen and oxygen atoms only
B)   one with a variety of atoms that are found in cells
C)   one with carbon and hydrogen atoms only
D)   one with carbon, hydrogen, and oxygen atoms only

Question 9

Glucose C6H12O6) has a single carbonyl group - C=O) in its linear form. Based on the number of oxygen atoms in glucose, how many hydroxyl groups - OH) would you expect glucose to have?

Accepted Answer

A)   6
B)   1
C)   3
D)   5

Question 10

Which of the following linkages would you expect to find at a branch point in glycogen or amylopectin?

Accepted Answer

A)   a- 1,4- glycosidic linkage
B)   fi- 1,4- glycosidic linkage
C)   a- 1,6- glycosidic linkage
D)   fi- 1,6- glycosidic linkage

Question 11

Use the following paragraph to answer to the corresponding questions).
Masatomo Kawakubo et al. reported in Science in August 2004 that the human stomach contains a natural, carbohydrate- base antibiotic that probably protects a large portion of the population from various diseases caused by the bacterium Helicobacter pylori. This bacterium has been linked to peptic ulcers, gastritis, and stomach cancer. This naturally occurring antibiotic is described by Kawakubo as having a terminal a1,4- linked N- acetylglucosamine NAG), and it acts by inhibiting the biosynthesis of a major component of the cell wall in H. pylori. [: M. Kawakubo et al., Science 305 2004): 1003.]
-Which of the following structures is most consistent with Kawakubo's description of this antibiotic?

Accepted Answer

A)   
B)   
C)  
D)

Question 12

Kawakubo's group created a glycoprotein with a terminal NAG i.e., a protein with NAG attached to its end). Their hypothesis is that the terminal NAG-and not the protein component-is responsible for the damage to the cell wall in H. pylori. What would be the most appropriate control for testing this hypothesis?

Accepted Answer

A)   Grow H. pylori in a test tube with glycoprotein that has its terminal NAG removed.
B)   Destroy the H. pylori by exposing them to a hypotonic solution. Then add the glycoprotein and observe.
C)   Expose other species of bacteria to the glycoprotein.
D)   Grow H. pylori in a test tube in vitro)  with no glycoprotein.

Question 13

What is the difference between an aldose sugar and a ketose sugar?

Accepted Answer

A)   the number of carbons
B)   the position of the hydroxyl groups
C)   one is a ring form, the other is a linear chain
D)   the position of the carbonyl group

Question 14

When an insect is crushed, it creates a crunching sound. What carbohydrate is the most likely source of this sound?

Accepted Answer

A)   cellulose
B)   glycogen
C)   chitin
D)   starch
E)   peptidoglycan

Question 15

Synthesis of larger sugars has allowed us to study them more in depth. Which of the following are potential benefits/reasons why we would want to study oligosaccharides in detail?

Accepted Answer

A)   Oligosaccharides are embedded in the cell membrane and help transport molecules across the membrane.
B)   Oligosaccharides form the part of the membrane bilayer that controls membrane permeability.
C)   Oligosacchrides are one of the information molecules of the cell.
D)   Oligosaccharides are present on cell surfaces and are part of cell identity mechanisms.

Question 16

You isolate an organic molecule that contains C, H, O, N, and S. This molecule

Accepted Answer

A)   could be cellulose.
B)   could be a glycoprotein.
C)   could be glycogen.
D)   is a nucleic acid.
E)   is a disaccharide.

Question 17

If you were going to develop a new antibiotic, you would probably need to become an expert on which of these carbohydrates?

Accepted Answer

A)   peptidoglycan
B)   cellulose
C)   starch
D)   chitin
E)   glycogen

Question 18

Which of the following do starch and cellulose have in common?

Accepted Answer

A)   the amount of hydrogen bonding that occurs between parallel strands
B)   their main function in plants
C)   the type of glycosidic linkage used
D)   the size of their monosaccharide subunits

Question 19

Which of the following can vary among monosaccharides?

Accepted Answer

A)   the presence of a carbonyl group
B)   the presence of hydroxyl groups
C)   the number of carbon atoms
D)   all of the above

Question 20

Which polysaccharide is an important component in the structure of many animals and fungi?

Accepted Answer

A)   amylose
B)   peptidoglycan
C)   chitin
D)   cellulose

Exam 5: An Introduction to Carbohydrates