Chapter 7 Flashcards
(137 cards)
1
Q
Green (chlorophyll-containing) plants produce
A
carbohydrates via photosynthesis.
2
Q
In the form of starch, they provide ________
for the plants
A
energy reserves
2
Q
Two main uses for the carbohydrates in
plants:
A
structural
, energy reserves
3
Q
In the form of cellulose, carbohydrates serves as ______
elements
A
structural
4
Q
it is a substance that do not contain carbon
A
Bioinorganic substances
5
Q
it a substances that contain carbon
A
Bioorganic Substances
6
Q
Recent studies have shown that cancer cells have high concentrations of sialic acid on their surfaces. What is the primary role of sialic acid in normal cells?
A) To provide energy reserves
B) To signal that a cell is “self” to the immune system
C) To aid in photosynthesis
D) To serve as a structural element
A
B) To signal that a cell is “self” to the immune system
7
Q
What implication does the high concentration of sialic acid on cancer cells have for the immune system’s ability to recognize these cells?
A) It enhances immune response against the cancer cells
B) It makes the cancer cells more visible to the immune system
C) It renders the cancer cells invisible to the immune system
D) It decreases the energy efficiency of the cancer cells
A
C) It renders the cancer cells invisible to the immune system
8
Q
Carbohydrates are classified as the most abundant bioorganic molecules on Earth. Which of the following statements best describes their role in plants?
A) They primarily serve as signaling molecules
B) They are involved in nutrient transport
C) They provide structural support and energy reserves
D) They play a minor role in photosynthesis
A
C) They provide structural support and energy reserves
9
Q
In the context of cancer research, why is the presence of sialic acid on tumor cells significant?
A) It indicates the tumor cells are undergoing apoptosis
B) It suggests a potential mechanism for immune evasion
C) It enhances the energy storage capacity of the tumor cells
D) It serves as a marker for healthy cell function
A
B) It suggests a potential mechanism for immune evasion
10
Q
Which carbohydrate component is primarily responsible for the structural integrity of plant cells?
A) Glucose
B) Starch
C) Cellulose
D) Sialic acid
A
C) Cellulose
10
Q
How do the roles of carbohydrates in plants differ from their roles in human cells, particularly regarding sialic acid?
A) In plants, carbohydrates are primarily for energy; in humans, they are for structural purposes.
B) In plants, carbohydrates serve structural and energy roles, while in humans, sialic acid helps prevent immune attack.
C) In plants, carbohydrates are used for photosynthesis; in humans, they are not present.
D) Both plants and humans use carbohydrates for energy only.
A
B) In plants, carbohydrates serve structural and energy roles, while in humans, sialic acid helps prevent immune attack.
10
Q
Carbohydrate storage, in the form of glycogen, provides a ______
A
short-term energy
reserve.
11
Q
Carbohydrates supply carbon atoms for the synthesis of other biochemical
substances( _______________
A
(proteins, lipids, and nucleic acids)
12
Q
Essential components in the mechanisms of genetic control of growth and
development of living cells
A
ribose, deoxyribose
13
Q
- a carbohydrate that contains a single polyhydroxy aldehyde or
polyhydroxy ketone unit.
A
Monosaccharide
13
Q
a carbohydrate that contains 3-10 monosaccharide units
covalently bonded to each other.
A
Oligosaccharide
13
Q
are structural components of cell membranes.
A
Lipid
14
Q
function in a variety of cell–cell and cell–
molecule recognition processes.
A
Protein
15
Q
– is a carbohydrate that contains two monosaccharide units covalently
bonded to each other
A
Disaccharide
16
Q
a polymeric carbohydrate that contains many monosaccharide
units covalently bonded to each other. The number of monosaccharide units present
A
Polysaccharide -
17
Q
What is the primary function of carbohydrates in the human diet?
A) To serve as vitamins
B) To provide energy, structural support, and biochemical building blocks
C) To act as hormones
D) To aid in digestion
A
B) To provide energy, structural support, and biochemical building blocks
18
Q
How much energy is released by the oxidation of carbohydrates per gram?
A) 2 kilocalories
B) 4 kilocalories
C) 7 kilocalories
D) 9 kilocalories
A
B) 4 kilocalories
19
Q
Which of the following statements correctly describes disaccharides?
A) They cannot be hydrolyzed into simpler units.
B) They consist of three to ten monosaccharide units.
C) They are composed of two monosaccharide units bonded together.
D) They are insoluble in water.
A
C) They are composed of two monosaccharide units bonded together.
20
Which type of carbohydrate consists of 3 to 10 monosaccharide units and is often associated with proteins and lipids?
A) Monosaccharide
B) Disaccharide
C) Oligosaccharide
D) Polysaccharide
C) Oligosaccharide
20
What is the role of carbohydrates in the genetic control of growth and development in living cells?
A) They serve as energy sources only.
B) They provide structural integrity to the cell membrane.
C) They act as essential components of ribose and deoxyribose, which are important for nucleic acids.
D) They facilitate protein synthesis.
C) They act as essential components of ribose and deoxyribose, which are important for nucleic acids.
21
What distinguishes polysaccharides from other carbohydrate types?
A) They are all water-insoluble.
B) They contain many monosaccharide units, varying from hundreds to over 50,000.
C) They can only be formed from glucose units.
D) They do not undergo hydrolysis.
B) They contain many monosaccharide units, varying from hundreds to over 50,000.
22
Which of the following carbohydrates is a common example of a disaccharide?
A) Starch
B) Sucrose
C) Cellulose
D) Fructose
B) Sucrose
23
What is the general empirical formula for simple carbohydrates?
A) CnH2n
B) CnH2nOn
C) Cn(H2O)n
D) CnH2n+1
C) Cn(H2O)n
24
It is a functional groups that is always present in carbohydrate molecule
hydroxyl
25
are images that coincide at all
points when the images are laid
upon each other.
Superimposable mirror images
25
Which of the following statements best defines a chiral carbon atom?
A) A carbon atom with only three different groups attached
B) A carbon atom that can form double bonds
C) A carbon atom that has four different groups bonded to it
D) A carbon atom that is found only in organic compounds
C) A carbon atom that has four different groups bonded to it
25
the complete hydrolysis of a polysaccharides produces many
monosaccharides
26
are images where not all
points coincide when the images
are laid upon each other
Nonsuperimposable mirror
images
27
What do the prefixes D- and L- indicate in the naming of monosaccharides?
A) The molecular weight of the carbohydrate
B) The solubility of the carbohydrate
C) The presence of chiral carbon atoms
D) The stereochemical configuration of the molecule
D) The stereochemical configuration of the molecule
27
A carbon atom that has four different groups bonded to it is called a
chiral carbon
28
Carbon 2 is a______
Chiral carbon
29
What is the significance of chirality in biological systems?
A) Chiral molecules do not interact with biological receptors.
B) Right-handed and left-handed forms of a chiral molecule can elicit different biological responses.
C) Chirality has no impact on drug efficacy.
D) All chiral forms have identical biological effects.
B) Right-handed and left-handed forms of a chiral molecule can elicit different biological responses.
30
If a molecule has three chiral centers, how many stereoisomeric forms can it potentially have?
A) 4
B) 6
C) 8
D) 16
C) 8
31
What characterizes nonsuperimposable mirror images in chiral molecules?
A) They coincide at all points when overlaid.
B) They do not coincide at all points when overlaid.
C) They represent identical compounds.
D) They can be easily interconverted.
B) They do not coincide at all points when overlaid.
31
Which of the following statements is true regarding the biological activity of chiral compounds?
A) Both enantiomers always have the same biological activity.
B) Only one enantiomer is typically active in biological systems.
C) Both forms are equally active regardless of structure.
D) Enantiomers can interact with the same receptors but produce identical effects.
B) Only one enantiomer is typically active in biological systems.
32
a chiral compound that rotates the plane of polarized
light in a clockwise direction.
dextrorotatory compound
32
In a molecule with two chiral centers, how many pairs of enantiomers can be produced?
A) 2
B) 4
C) 8
D) 16
B) 4
33
What is a key characteristic of enantiomers in terms of their interaction with polarized light?
A) They do not interact with polarized light.
B) They rotate the plane of polarized light in opposite directions.
C) They both rotate polarized light in the same direction.
D) They are not optically active.
B) They rotate the plane of polarized light in opposite directions.
33
a chiral compound that rotates the plane of polarized light
in a counterclockwise direction.
levorotatory compound
34
Which term describes a compound that rotates the plane of polarized light clockwise?
A) Levorotatory
B) Dextrorotatory
C) Chiral
D) Achiral
B) Dextrorotatory
35
In a molecule with three chiral centers, how many maximum stereoisomers can be formed?
A) 4
B) 6
C) 8
D) 16
C) 8
36
Why might both enantiomers of a chiral compound not have the same biological activity?
A) They are structurally identical.
B) They interact differently with biological receptors.
C) Both forms are usually inactive.
D) They do not participate in metabolic reactions.
B) They interact differently with biological receptors.
37
If one member of an enantiomeric pair is levorotatory, what can be said about the other member?
A) It is also levorotatory.
B) It is dextrorotatory.
C) It has no optical activity.
D) It is an achiral compound.
B) It is dextrorotatory.
38
What does it mean for a compound to be optically active?
A) It has multiple chiral centers.
B) It can rotate the plane of polarized light.
C) It has no chiral centers.
D) It cannot exist as stereoisomers.
B) It can rotate the plane of polarized light.
39
is a chiral compound that rotates the plane of polarized
light in a clockwise direction.
dextrorotatory compound
40
is a chiral compound that rotates the plane of polarized light
in a counterclockwise direction.
levorotatory compound
41
Why do enantiomers have identical boiling points, melting points, and densities?
A) They have different functional groups.
B) Intermolecular force strength depends on chirality.
C) Intermolecular force strength does not depend on chirality.
D) They react differently with achiral solvents.
C) Intermolecular force strength does not depend on chirality.
42
Which statement best explains the solubility of enantiomers in different solvents?
A) Enantiomers are soluble in achiral solvents but not in chiral solvents.
B) Enantiomers have the same solubility in achiral solvents but different solubilities in chiral solvents.
C) Enantiomers have different solubilities in both achiral and chiral solvents.
D) Enantiomers are equally soluble in all solvents regardless of chirality.
B) Enantiomers have the same solubility in achiral solvents but different solubilities in chiral solvents.
43
The rate and extent of reaction of enantiomers with a chiral reactant are:
A) Always the same regardless of the chirality of the reactant.
B) Different if the reactant is chiral, the same if the reactant is achiral.
C) Always slower for one enantiomer.
D) Independent of the solvent used.
B) Different if the reactant is chiral, the same if the reactant is achiral.
43
What is the effect of chirality on interactions between enantiomers and receptor sites in the human body?
A) The responses are identical because chirality does not affect biological interactions.
B) Enantiomers generate different responses as receptor sites in the body are achiral.
C) Enantiomers generate the same response regardless of receptor chirality.
D) Enantiomers generate different responses because receptor sites in the body are chiral.
D) Enantiomers generate different responses because receptor sites in the body are chiral.
44
What is the key factor that allows enantiomers to have different biological effects despite having identical physical properties?
A) Different intermolecular forces.
B) Chirality of receptor sites in biological systems.
C) Different solubility in all solvents.
D) The ability to form different covalent bonds.
B) Chirality of receptor sites in biological systems.
44
If the D isomer of a hormone produces a response 20 times greater than the L isomer, what can you infer about the interaction of enantiomers with biological systems?
A) Both isomers always produce the same biological response.
B) The L isomer is always more active than the D isomer.
C) The difference in response is due to the chirality of the receptor sites in the body.
D) Biological systems cannot distinguish between D and L isomers.
C) The difference in response is due to the chirality of the receptor sites in the body.
45
is a monosaccharide that contains an aldehyde functional group. they are also
polyhydroxy aldehydes.
aldose
46
Which of the following statements is true regarding the interaction of enantiomers with achiral molecules?
A) Enantiomers react at different rates with achiral molecules.
B) Enantiomers have identical interactions with achiral molecules.
C) Achiral molecules prefer one enantiomer over the other.
D) Achiral molecules cannot react with enantiomers.
B) Enantiomers have identical interactions with achiral molecules.
47
is a monosaccharide that contains a ketone functional group. they are also
polyhydroxy ketones.
ketose
48
Which of the following best describes an aldose?
A) A monosaccharide with a ketone group.
B) A monosaccharide with an aldehyde group.
C) A monosaccharide with a hydroxyl group.
D) A disaccharide containing two monosaccharides
B) A monosaccharide with an aldehyde group.
48
An aldose with 3 carbons is an _______
aldotriose
49
A ketose with 6 carbons is a
ketohexose
50
What functional group does a ketose contain?
A) An aldehyde group.
B) A hydroxyl group.
C) A carboxyl group.
D) A ketone group.
D) A ketone group.
50
How would you classify a monosaccharide with 6 carbons and a ketone group?
A) Aldotriose
B) Aldohexose
C) Ketohexose
D) Ketotriose
C) Ketohexose
50
Which of the following is not a property of D-glyceraldehyde?
A) It is the simplest chiral monosaccharide.
B) It is an intermediate in glycolysis.
C) It is synthesized from glucose in the body.
D) It is an achiral molecule.
D) It is an achiral molecule.
51
Which of the following is true about dihydroxyacetone?
A) It contains an aldehyde functional group.
B) It is a chiral molecule.
C) It is an intermediate in glycolysis.
D) It is an aldotriose.
C) It is an intermediate in glycolysis.
51
Which of the following monosaccharides is not encountered as a free monosaccharide but serves as an important intermediate in metabolic processes?
A) D-glucose
B) D-glyceraldehyde
C) D-ribose
D) D-mannose
D) D-mannose
52
Monosaccharides are classified based on:
A) Only the number of hydroxyl groups they contain.
B) The number of carbon atoms and the type of carbonyl group they contain.
C) The position of hydroxyl groups and their solubility.
D) Whether they are found in plants or animals.
B) The number of carbon atoms and the type of carbonyl group they contain.
52
Which of the following sugars is commonly known as "brain sugar" due to its presence in glycoproteins in brain and nerve tissue?
A) D-glucose
B) D-galactose
C) D-ribose
D) D-mannose
B) D-galactose
53
53
Which of the following molecules is not chiral?
A) D-glucose
B) D-glyceraldehyde
C) D-galactose
D) Dihydroxyacetone
D) Dihydroxyacetone
54
it act as a reducing agent in such reactions
reducing
sugars.
55
converting specific monosaccharides into acidic derivatives by oxidizing their hydroxyl or aldehyde groups.
Oxidation to Produce Acidic Sugars
56
TRUE OR FALSE
all monosaccharides, both aldoses and
ketoses are reducing sugars.
True
57
in biochemical systems, enzymes can oxidize the primary alcohol end of an aldose such as glucose, without oxidizing the aldehyde group, to produce which type of acid?
alduronic acid
58
Which of the following statements correctly describes why ketoses, such as fructose, are considered reducing sugars in basic solutions?
A. Ketoses are inherently reducing sugars due to their ketone group.
B. Ketoses convert to their cyclic form in basic conditions, which then acts as a reducing sugar.
C. Ketoses rearrange to form an aldose under basic conditions, allowing them to act as reducing sugars.
D. Ketoses are only reducing sugars when paired with an aldose in a reaction.
C. Ketoses rearrange to form an aldose under basic conditions, allowing them to act as reducing sugars.
59
In biochemical systems, enzymes can oxidize the primary alcohol group of an aldose without affecting the aldehyde group. Which of the following products is formed due to this selective oxidation?
A. Aldonic acid
B. Uronic acid
C. Aldaric acid
D. Keto acid
B. Uronic acid
60
When glucose reacts with Tollens' reagent, it serves as a reducing agent and forms which of the following products?
A. Aldaric acid and metallic silver
B. Aldonic acid and metallic silver
C. Uronic acid and Ag++
ions
D. Aldonic acid and Cu++
ions
B. Aldonic acid and metallic silver
61
A strong oxidizing agent can oxidize both the aldehyde and the primary alcohol group of an aldose to form which type of compound?
A. Alduronic acid
B. Polyhydroxy monocarboxylic acid
C. Aldonic acid
D. Aldaric acid
D. Aldaric acid
62
Which of the following statements correctly describes the role of the open-chain form of a monosaccharide in oxidation reactions with Tollens’ and Benedict’s solutions?
A. The open-chain form is required to provide a hydroxyl group, which is the reducing agent.
B. The open-chain form provides a free aldehyde group necessary for oxidation.
C. The open-chain form offers a ketone group that reduces Ag
++
and Cu
2+2+
ions.
D. The open-chain form stabilizes the cyclic form, which reacts with Tollens' solution.
B. The open-chain form provides a free aldehyde group necessary for oxidation.
63
Which combination of reagents and reactions correctly leads to the production of aldonic acid?
A. Benedict's solution with glucose, reducing Cu
2+2+
to Cu
++
B. Tollens' solution with ketoses, forming an aldaric acid
C. A strong oxidizing agent with an aldose, reducing both the aldehyde and alcohol groups
D. Enzymatic oxidation of an aldose, reducing the primary alcohol only
A. Benedict's solution with glucose, reducing Cu
2+2+
to Cu
++
64
Under basic conditions, both aldoses and ketoses are reducing sugars because:
A. Ketoses are converted to aldoses, which then act as reducing agents.
B. Both aldoses and ketoses contain free aldehyde groups.
C. Ketoses contain carboxylic acids that react with oxidizing agents.
D. Aldoses form cyclic ketones in basic conditions, acting as reducing sugars.
A. Ketoses are converted to aldoses, which then act as reducing agents.
65
are a type of carbohydrate that is derived from sugars but differs slightly in structure and function.
Sugar alcohols
66
is an acetal formed from a cyclic monosaccharide by replacement of the
hemiacetal carbon -OH group with an -OR group.
glycoside
67
It is a colorless, odorless, and non-volatile crystalline liquid that dissolves easily in water.
Phosphoric acid
68
long-chain polymer made up of glucose-derived molecules. It’s a type of polysaccharide (similar to cellulose). It is primarily found in the exoskeletons of arthropods (like insects, crabs, and lobsters), as well as in the cell walls of fungi.
Chitin
69
produced whenever the polysaccharide______breaks down
Starch
69
it is made up of two D-glucose units, one of which must be α-D-glucose
Maltose
70
It is a glycosaminoglycan (a type of carbohydrate molecule) and has a unique ability to retain water, helping to keep tissues well-hydrated, plump, and lubricated.
Hyaluronic acid
71
it is a (malt=germinated barley that has been baked and ground;
contains this disaccharide)
malt sugar
72
* an intermediate in the hydrolysis of the polysaccharide_________
cellulose
73
contains two D-glucose monosaccharide units
cellobiose
74
what is the enzyme that breaks the glucose–glucose α(1→4) linkage present in
maltose, is found both in the human body and in yeast.
Maltase
75
Which of the following characteristics is shared by both maltose and cellobiose?
A) Both contain an α(1→4) linkage between two D-glucose units.
B) Both are easily digested by humans and can be fermented by yeast.
C) Both are reducing sugars and produce two D-glucose molecules upon hydrolysis.
D) Both are components of cellulose and are intermediate products in its hydrolysis.
C) Both are reducing sugars and produce two D-glucose molecules upon hydrolysis.
76
Which of the following best describes maltose?
A) It is a polysaccharide formed by the α(1→4) linkage between two D-glucose units, one of which is β-D-glucose.
B) It is a disaccharide composed of two D-glucose units, connected by an α(1→4) linkage, and is commonly called malt sugar.
C) It is a disaccharide that cannot be broken down by human enzymes and is primarily found in cellulose.
D) It is a disaccharide formed by the β(1→4) linkage between two D-glucose units and is commonly called cellobiose.
B) It is a disaccharide composed of two D-glucose units, connected by an α(1→4) linkage, and is commonly called malt sugar.
77
What is required for the hydrolysis of maltose into two D-glucose molecules?
A) The enzyme cellobiase or an acidic environment
B) The enzyme maltase or an acidic environment
C) The enzyme maltase or a basic environment
D) The enzyme cellulase or a neutral environment
B) The enzyme maltase or an acidic environment
78
Which statement best explains why humans cannot digest cellobiose?
A) Humans lack the enzyme maltase to break down the β(1→4) linkage.
B) Humans lack the enzyme cellobiase to break down the β(1→4) linkage in cellobiose.
C) Humans lack the enzyme maltase to break down the α(1→4) linkage in cellobiose.
D) Humans lack the enzyme lactase to break down the β(1→4) linkage in cellobiose.
B) Humans lack the enzyme cellobiase to break down the β(1→4) linkage in cellobiose.
79
Which of the following statements correctly differentiates maltose from cellobiose?
A) Maltose contains two D-glucose units with a β(1→4) linkage, while cellobiose contains an α(1→4) linkage.
B) Humans can digest maltose, whereas cellobiose cannot due to the lack of the cellobiase enzyme.
C) Maltose is not fermentable by yeast, whereas cellobiose is fermentable by yeast.
D) Maltose is found in cellulose, whereas cellobiose is found in germinated barley.
B) Humans can digest maltose, whereas cellobiose cannot due to the lack of the cellobiase enzyme.
80
Why is cellobiose not fermentable by yeast?
A) It contains a β(1→4) linkage between two D-glucose units, and yeast lacks the enzyme to break this linkage.
B) It contains an α(1→4) linkage that yeast cannot metabolize.
C) It lacks a hemiacetal group, making it non-fermentable.
D) It contains two D-glucose units that cannot be broken down by any enzyme.
A) It contains a β(1→4) linkage between two D-glucose units, and yeast lacks the enzyme to break this linkage.
81
In what way do maltose and cellobiose differ in terms of their glucose linkage configuration?
A) Maltose has an α(1→4) linkage, while cellobiose has a β(1→4) linkage.
B) Maltose has a β(1→4) linkage, while cellobiose has an α(1→4) linkage.
C) Both have β(1→4) linkages, but differ in the types of glucose units.
D) Both have α(1→4) linkages but differ in digestion by humans.
A) Maltose has an α(1→4) linkage, while cellobiose has a β(1→4) linkage.
82
Which of the following best explains why maltose is readily fermented by yeast, but cellobiose is not?
A) Yeast can only ferment sugars with a β(1→4) linkage.
B) Maltose has an α(1→4) linkage, which yeast enzymes can break, whereas cellobiose has a β(1→4) linkage, which yeast enzymes cannot break.
C) Cellobiose lacks the hemiacetal form required for fermentation.
D) Maltose is a polysaccharide, while cellobiose is a disaccharide, affecting yeast fermentation.
B) Maltose has an α(1→4) linkage, which yeast enzymes can break, whereas cellobiose has a β(1→4) linkage, which yeast enzymes cannot break.
83
Both the human body and yeast lack the enzyme cellobiase needed to break the
glucose–glucose β(1→4) linkage of cellobiose ( T or F )
TRUE
83
it is made up of a β-D-galactose unit
and a D-glucose unit joined by a
β(1→4) linkage glycosidic linkage.
Lactose
83
The glucose hemiacetal center is
unaffected when galactose bonds to
glucose in the formation of lactose,
so lactose is a?
reducing sugar
84
Lactose can be hydrolyzed by acid or by the enzyme _______, forming an
equimolar mixture of galactose and glucose.
lactase
85
it is the most abundant of all disaccharides
and occurs throughout the plant
kingdom.
Sucrose
86
it is a condition in which people lack the enzyme lactase;
lactose intolerance
87
When sucrose is cooked with
acid-containing foods such as
fruits or berries, partial
hydrolysis takes place, forming
some ______/
invert sugar
87
what are carbohydrates that contain three to ten monosaccharide units.
Oligosaccharides
88
Which two monosaccharides make up lactose?
A) α-D-glucose and β-D-glucose
B) β-D-galactose and D-glucose
C) α-D-glucose and β-D-fructose
D) β-D-glucose and D-galactose
B) β-D-galactose and D-glucose
89
What type of glycosidic linkage connects the monosaccharide units in lactose?
A) α(1→4) linkage
B) β(1→4) linkage
C) α,β(1→2) linkage
D) β(1→6) linkage
B) β(1→4) linkage
90
Why is lactose considered a reducing sugar?
A) It contains an α(1→2) linkage, allowing it to open to form an aldehyde.
B) The β(1→4) linkage enables both glucose and galactose rings to open, exposing an aldehyde group.
C) The glucose ring in lactose can open due to its hemiacetal center, which can give an aldehyde group.
D) The galactose ring in lactose can open due to its anomeric carbon atom.
C) The glucose ring in lactose can open due to its hemiacetal center, which can give an aldehyde group.
91
What happens when individuals with lactose intolerance consume lactose?
A) Lactose is absorbed directly into the bloodstream, causing high blood sugar.
B) Lactose remains undigested in the intestine, attracting water and causing fullness, discomfort, and other symptoms.
C) Lactose is broken down too rapidly, leading to a sugar spike and immediate hunger.
D) Lactose is converted into glucose and stored in muscles, causing cramps and nausea.
B) Lactose remains undigested in the intestine, attracting water and causing fullness, discomfort, and other symptoms.
92
Which populations are least likely to experience lactose intolerance?
A) Native North Americans and Southeast Asians
B) Africans and Greeks
C) Scandinavians and other northern Europeans
D) Native South Americans and Australians
C) Scandinavians and other northern Europeans
93
What are the products of lactose hydrolysis by acid or lactase?
A) Two glucose molecules
B) Galactose and fructose
C) Galactose and glucose
D) Glucose and sucrose
C) Galactose and glucose
94
Why do adult animals generally not consume milk?
A) They lack the enzyme lactase and cannot digest lactose effectively.
B) They require more complex carbohydrates for energy.
C) They develop an intolerance to proteins in milk rather than lactose.
D) They produce an excess of lactase but cannot process it.
A) They lack the enzyme lactase and cannot digest lactose effectively.
95
What effect does bacterial fermentation of undigested lactose in the intestine have?
A) It produces glucose and galactose, easing digestion.
B) It creates lactic acid and gas, which increases discomfort.
C) It eliminates symptoms of lactose intolerance by breaking down lactose.
D) It produces energy and aids digestion without discomfort.
B) It creates lactic acid and gas, which increases discomfort.
96
How does the structure of lactose differ from that of sucrose?
A) Lactose has a reducing glucose ring, while sucrose has no reducing sugar characteristics.
B) Lactose is a nonreducing sugar, while sucrose is a reducing sugar.
C) Both lactose and sucrose contain β-D-galactose, but in different linkages.
D) Lactose has an α,β(1→2) linkage, whereas sucrose has a β(1→4) linkage.
A) Lactose has a reducing glucose ring, while sucrose has no reducing sugar characteristics.
97
Why does cooking sucrose with acid-containing foods make jams and jellies sweeter?
A) Acid catalyzes the hydrolysis of sucrose into galactose and glucose.
B) Acid catalyzes the partial hydrolysis of sucrose, forming invert sugar, which tastes sweeter.
C) Acid breaks down sucrose into lactose, which enhances sweetness.
D) Acid changes the structure of sucrose, causing it to crystallize and taste sweeter.
B) Acid catalyzes the partial hydrolysis of sucrose, forming invert sugar, which tastes sweeter.
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is a polysaccharide in which only one type of
monosaccharide monomer is present
A homopolysaccharide
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what breaks down complex sugars (disaccharides) into simple sugars (monosaccharides) so they can be absorbed and used for energy.
Disaccharide hydrolysis
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What are oligosaccharides?
A) Carbohydrates made up of two monosaccharide units
B) Carbohydrates that contain three to ten monosaccharide units
C) Long-chain polysaccharides with more than 50,000 monomers
D) Simple sugars composed of single monosaccharide units
B) Carbohydrates that contain three to ten monosaccharide units
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is a polysaccharide in which more than one (usually
two) type of monosaccharide monomer is present.
heteropolysaccharide
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Why do humans experience discomfort and gas after consuming foods high in raffinose and stachyose?
A) These oligosaccharides are rapidly absorbed into the bloodstream, causing discomfort.
B) Humans lack the enzymes to digest these oligosaccharides, so they pass undigested to the large intestine, where bacteria act on them.
C) Raffinose and stachyose break down immediately in the stomach, causing gas.
D) Humans digest raffinose and stachyose too quickly, leading to cramps and nausea.
B) Humans lack the enzymes to digest these oligosaccharides, so they pass undigested to the large intestine, where bacteria act on them.
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Which of the following foods contain the oligosaccharides raffinose and stachyose?
A) White rice and potatoes
B) Onions, cabbage, beans, and whole wheat
C) Milk, cheese, and yogurt
D) Apples, bananas, and grapes
B) Onions, cabbage, beans, and whole wheat
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What is another name for a polysaccharide?
A) Starch
B) Glycan
C) Glucose
D) Monosaccharide
B) Glycan
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What happens to potatoes when they are exposed to sunlight?
A) Their carbohydrate content decreases.
B) They produce more raffinose and stachyose.
C) They increase the toxin solanine and may turn green.
D) Their protein levels increase.
C) They increase the toxin solanine and may turn green.
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What is the difference between a homopolysaccharide and a heteropolysaccharide?
A) A homopolysaccharide contains two types of monosaccharides, while a heteropolysaccharide contains only one.
B) A homopolysaccharide contains only one type of monosaccharide, while a heteropolysaccharide contains more than one type.
C) Homopolysaccharides are longer than heteropolysaccharides.
D) Heteropolysaccharides are only found in plants, while homopolysaccharides are found in animals.
B) A homopolysaccharide contains only one type of monosaccharide, while a heteropolysaccharide contains more than one type.
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What is the term used to describe the branching pattern in polysaccharides?
A) Monomer repetition
B) Degree of polymerization
C) Degree of branching
D) Chain elongation
C) Degree of branching
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Which of the following is an important factor that distinguishes polysaccharides from one another?
A) The amount of water in the polysaccharide
B) The solubility of the polysaccharide in alcohol
C) The type of glycosidic linkage between monomer units
D) The color of the polysaccharide in solution
C) The type of glycosidic linkage between monomer units
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What function does solanine serve in potato plants?
A) It promotes starch storage.
B) It acts as a defense toxin against insects and predators.
C) It helps potatoes grow faster in sunlight.
D) It assists in nutrient absorption from the soil.
B) It acts as a defense toxin against insects and predators.
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Which statement is true about glycans?
A) All glycans are composed of only glucose units.
B) Glycans are another term for oligosaccharides.
C) Glycans refer to all types of polysaccharides, with varying lengths, glycosidic linkages, and branching.
D) Glycans only refer to unbranched polysaccharides.
C) Glycans refer to all types of polysaccharides, with varying lengths, glycosidic linkages, and branching.
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is a polysaccharide that is a storage form for monosaccharides
and is used as an energy source in cells.
A storage polysaccharide
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has a structure similar to that of amylopectin; all glycosidic linkages are of
the a type, and both (1→4) and (1→6) linkages are present.
Glycogen
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