Question 1

In animals, the role of carbohydrate polymers is primarily
A) enzymes.
B) information storage.
C) energy storage.
D) body protection.

Accepted Answer

Carbohydrate polymers in animals are primarily used for energy storage. The most common carbohydrate polymer in animals is glycogen, which is stored in the liver and muscles and used as a source of energy.

Question 2

Which polysaccharide is an important component in the structure of many animals and fungi?
A) amylose
B) peptidoglycan
C) chitin
D) cellulose

Accepted Answer

Chitin is a polysaccharide that is an important component in the structure of many animals (such as insects and crustaceans) and fungi, providing structural support and protection. Amylose is a polysaccharide found in plants, peptidoglycan is found in bacterial cell walls, and cellulose is also found in plant cell walls.

Question 3

When an insect is crushed, it creates a crunching sound. What carbohydrate is the most likely source of this sound?
A) cellulose
B) glycogen
C) chitin
D) starch
E) peptidoglycan

Accepted Answer

Chitin is a complex carbohydrate that makes up the exoskeleton of insects. When an insect is crushed, the chitin in its exoskeleton creates a crunching sound. Cellulose, glycogen, starch, and peptidoglycan are not typically found in the exoskeleton of insects and would not produce the same sound.

Question 4

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?
A) 
B) 
C)

D)

Accepted Answer

The description of the antibiotic includes a terminal a1,4-linked N-acetylglucosamine (NAG) structure which is consistent with the structure shown in choice C. The other structures do not have the same terminal NAG structure described by Kawakubo.

Question 5

Cell walls are used by many different organisms for protection from their environment and structural support. These cell walls must obviously be insoluble in water, otherwise, they would dissolve the first time the organism got wet. Which of the following carbohydrates would you expect to be the most soluble in water?
A) cellulose
B) starch
C) peptidoglycan
D) chitin

Accepted Answer

Starch is a polysaccharide made up of glucose monomers and is highly soluble in water. Cellulose, peptidoglycan, and chitin are also polysaccharides but have a more rigid structure and are hence insoluble in water.

Question 6

Why do endurance athletes practice "carbohydrate loading," meaning to eat massive amounts of starch in the days leading up to a long race?
A) Starch is used as a building block for the synthesis of many other molecules.
B) Carbohydrates are reduced molecules that can provide the chemical energy required during exercise.
C) Starch can be used to synthesize cellulose and build up the cell walls of muscles.
D) Starch provides dietary fiber or "roughage" that aids digestion.

Accepted Answer

Carbohydrates are broken down in the body to provide glucose, which is used for energy. Endurance athletes require large amounts of energy to sustain prolonged exercise, and carbohydrate loading ensures they have sufficient glucose stores to meet these demands.

Question 7

Why do plants require sunlight?
A) Sunlight helps plants break down their food products so they can extract the energy stored in them.
B) Sunlight can be used directly by plants to perform a number of physiological processes.
C) Sunlight energy can be used by plants to reduce the carbon atoms in carbon dioxide.
D) Sunlight oxidizes carbon dioxide and water to form glucose.

Accepted Answer

Sunlight is essential for photosynthesis, where plants convert carbon dioxide and water into glucose and oxygen using the energy from sunlight. This process involves reducing carbon atoms in carbon dioxide to form glucose.

Question 8

Which of the following polysaccharides is made up of highly branched helices?
A) glycogen
B) cellulose
C) chitin
D) peptidoglycan

Accepted Answer

Glycogen is made up of highly branched helices, which allows for efficient storage and quick release of glucose for energy. Cellulose is made up of long, unbranched chains and is a major component of plant cell walls. Chitin is a linear polymer with a nitrogen-containing group and is found in the exoskeletons of insects and crustaceans. Peptidoglycan is a polymer that makes up the cell walls of bacteria and is composed of sugars and amino acids.

Question 9

Which of the following polysaccharides is made up of parallel strands joined together by peptide bonds?
A) peptidoglycan
B) cellulose
C) starch
D) glycogen

Accepted Answer

Peptidoglycan is a component of bacterial cell walls and is made up of parallel strands of alternating N-acetylglucosamine and N-acetylmuramic acid molecules, joined together by peptide bonds. Cellulose is made up of parallel strands of glucose molecules linked by beta-1,4 glycosidic bonds, but not peptide bonds. Starch and glycogen are both composed of glucose molecules linked by alpha-1,4 glycosidic bonds, but do not contain peptide bonds.

Question 10

Which of the following enzymes catalyzes the hydrolysis of a- glycosidic linkages in glycogen?
A) glycolase
B) phosphorylase
C) amylase

Accepted Answer

Phosphorylase catalyzes the hydrolysis of a-glycosidic linkages in glycogen. Glycolase and amylase are enzymes that catalyze the hydrolysis of different types of glycosidic linkages in other carbohydrates.

Question 11

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

Accepted Answer

Molecules with carbon and hydrogen atoms only, such as hydrocarbons, have the most free energy per gram because their bonds have the highest potential energy. This is due to both the high electronegativity difference between carbon and hydrogen, and the lack of polar groups that can stabilize the molecule.

Question 12

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?
A) as a hexose
B) as a disaccharide
C) as a polysaccharide
D) as a pentose
E) as a monosaccharide

Accepted Answer

Lactose is a disaccharide because it is composed of two monosaccharides, glucose and galactose, joined together by a glycosidic linkage.

Question 13

Which of the following enzymes catalyzes the hydrolysis of a- glycosidic linkages in starch?
A) phosphorylase
B) glycolase
C) amylase

Accepted Answer

Amylase is the enzyme that catalyzes the hydrolysis of a- glycosidic linkages in starch. Phosphorylase catalyzes the addition of a phosphate group to a molecule, and glycolase catalyzes the breakdown of glucose.

Question 14

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?
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.

Accepted Answer

To test whether the terminal NAG is responsible for the damage to the cell wall in H. pylori, a control should be used in which the glycoprotein has its terminal NAG removed. This will allow for the comparison of the effects of the glycoprotein with and without the NAG component on H. pylori cell walls. Option B is not appropriate as it does not address the hypothesis being tested. Option C is not relevant as it does not involve H. pylori, which is the focus of the hypothesis. Option D is not appropriate as it does not allow for the comparison of the effects of the glycoprotein with and without the NAG component.

Question 15

Which of the following polysaccharides is made up of parallel strands joined together by hydrogen bonds?
A) peptidoglycan
B) glycogen
C) chitin
D) starch

Accepted Answer

Chitin is made up of parallel strands of N-acetylglucosamine joined together by hydrogen bonds, giving it a strong and rigid structure.

Question 16

Which of the following categories includes all others in the list?
A) monosaccharide
B) carbohydrate
C) starch
D) polysaccharide
E) disaccharide

Accepted Answer

Carbohydrate is the broadest category and includes all other categories listed, including monosaccharides, disaccharides, polysaccharides, and starch.

Question 17

Compare the molecular formula of a carbohydrate CH₂O)_nwith that of carbon dioxide CO₂). What does the presence of hydrogen atoms in carbohydrates indicate? A) Every carbon atom in a carbohydrate is bonded to four different atoms. B) Carbohydrates are more reduced than carbon dioxide. C) Carbohydrates contain a carbonyl functional group. D) Carbohydrates are more oxidized than carbon dioxide.

Accepted Answer

The presence of hydrogen atoms in carbohydrates indicates that they are more reduced than carbon dioxide, which lacks hydrogen atoms. This means that carbohydrates have more potential energy stored in their chemical bonds, making them a good source of energy for living organisms.

Question 18

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

Accepted Answer

Glucose has a total of 6 oxygen atoms. One of these is part of the carbonyl group (C=O), leaving 5 oxygen atoms to be part of hydroxyl groups (OH). Therefore, glucose has 5 hydroxyl groups.

Question 19

Which of the following best explains why "carbs" carbohydrates) are advertised by manufacturers of candy bars and sports drinks as a "quick energy boost"?
A) This is an advertising gimmick that has no scientific evidence to support it.
B) The carbons in carbs are rich in energy because they are highly oxidized.
C) The energy in them can be stored as fat, which has high energy per unit weight.
D) Carbs are reduced molecules that have high- energy electrons.

Accepted Answer

Carbohydrates are composed of carbon, hydrogen, and oxygen, where the carbon atoms are in a reduced form. This means they can undergo oxidation reactions in the body, releasing energy in the process. This energy is readily available, making carbs an immediate source of energy, which is why they are often marketed as providing a "quick energy boost."

Question 20

If you were going to develop a new antibiotic, you would probably need to become an expert on which of these carbohydrates?
A) peptidoglycan
B) cellulose
C) starch
D) chitin
E) glycogen

Accepted Answer

Peptidoglycan is a major component of bacterial cell walls and is a potential target for antibiotics. Developing an antibiotic that specifically targets peptidoglycan synthesis or degradation could be an effective treatment for bacterial infections. Cellulose, starch, chitin, and glycogen are all carbohydrates found in various organisms, but are not necessarily relevant in the development of antibiotics.

Quiz 5: An Introduction to Carbohydrates

In animals, the role of carbohydrate polymers is primarily

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

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

Why do endurance athletes practice "carbohydrate loading," meaning to eat massive amounts of starch in the days leading up to a long race?

Why do plants require sunlight?

Which of the following polysaccharides is made up of highly branched helices?

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

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

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

Lactose, a sugar in milk, is composed of one glucose molecule joined by a glycosidic linkage to one galactose molecule. How is lactose classified?

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

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

Which of the following categories includes all others in the list?

Compare the molecular formula of a carbohydrate CH₂O) _nwith that of carbon dioxide CO₂) . What does the presence of hydrogen atoms in carbohydrates indicate?

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?

Which of the following best explains why "carbs" carbohydrates) are advertised by manufacturers of candy bars and sports drinks as a "quick energy boost"?

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