Chapter 6 – Protein: Amino Acids
MULTIPLE CHOICE
1. What is the primary factor that differentiates one amino acid from another?
a.
The side group
b.
The central carbon atom
c.
The number of oxygen atoms
d.
The number of nitrogen atoms
e.
The presence of a central hydrogen atom
2. Which element is found in certain amino acids?
a.
Iron
b.
Sulfur
c.
Calcium
d.
Potassium
e.
Mercury
3. Which term is used to classify amino acids in the diet?
a.
Essential
b.
Unessential
c.
Partially essential
d.
Moderately essential
e.
Rarely essential
4. Which item is contained in an amino acid?
a.
An acid group
b.
An ester group
c.
An aldehyde group
d.
A central hydrogen atom
e.
A central oxygen atom
5. What is the simplest amino acid?
a.
Valine
b.
Glycine
c.
Alanine
d.
Methionine
e.
Tryptophan
6. Which item is a nonessential amino acid in human nutrition?
a.
Proline
b.
Threonine
c.
Methionine
d.
Tryptophan
e.
Phenylalanine
7. Which item is an essential amino acid?
a.
Cysteine
b.
Leucine
c.
Glutamine
d.
Serine
e.
Alanine
8. What amino acid is classified as conditionally essential when dietary intake of phenylalanine is
insufficient or the body cannot normally metabolize phenylalanine?
a.
Cysteine
b.
Tyrosine
c.
Glutamine
d.
Isoleucine
e.
Asparagine
9. What type of reaction is required to bind two molecules of glycine together and release a molecule of
water?
a.
Hydrolysis
b.
Deamination
c.
Denaturation
d.
Condensation
e.
Transnaturation
10. When two amino acids are chemically joined together, the resulting structure is called a ____.
a.
dipeptide
b.
diglyceride
c.
polypeptide
d.
disaccharide
e.
polysaccharide
11. Which of the following is a feature of hemoglobin?
a.
It has no tertiary structure.
b.
It holds the mineral calcium.
c.
It is constructed of four polypeptide chains.
d.
It has no primary or secondary structure.
e.
It is a ring protein.
12. An example of a protein with quaternary polypeptide structures is ____.
a.
insulin
b.
tryptophan
c.
hemoglobin
d.
disulfide bridges
e.
valine
13. What is the process by which heat or acidity disrupts the normal shape of a protein chain?
a.
Digestion
b.
Condensation
c.
Denaturation
d.
Hydrogenation
e.
Hydrolysis
14. The application of heat or acid to a protein that causes its shape to change is known as ____.
a.
stiffening
b.
condensation
c.
denaturation
d.
destabilization
e.
hydrolization
15. In what organ is pepsin active?
a.
Stomach
b.
Pancreas
c.
Small intestine
d.
Large intestine
e.
Liver
16. What digestive enzyme would be most affected in people who are unable to produce hydrochloric
acid?
a.
Pepsin
b.
Transaminase
c.
Pancreatic protease
d.
Intestinal peptidase
e.
Salivary protease
17. The function of a protease is to ____.
a.
hydrolyze proteins
b.
synthesize proteins
c.
hydrolyze ribosomes
d.
synthesize ribosomes
e.
synthesize macrophages
18. The chief function of pepsin is to ____.
a.
emulsify dietary proteins
b.
activate hydrochloric acid
c.
activate pancreatic proteases
d.
cleave proteins into smaller polypeptides
e.
renature nonessential proteins
19. What is the usual fate of orally ingested enzyme supplements?
a.
Digestion by gastrointestinal proteases
b.
Rapidly degradation by salivary secretions
c.
Almost complete absorption in original form from the stomach
d.
Complete absorption in original form from the jejunum
e.
Rapid excretion through the digestive system
20. What best describes the structure of pepsin?
a.
Lipid
b.
Protein
c.
Nucleic acid
d.
Carbohydrate
e.
Sterol
21. The process whereby messenger RNA is made from a DNA template is ____.
a.
expression
b.
sequencing
c.
transcription
d.
ribosome assembly
e.
translation
22. What is a ribosome?
a.
A template for protein synthesis
b.
A hard knot of subcutaneous protein mass
c.
A structure upon which proteins are assembled
d.
An antibody synthesized by specialized immune cells
e.
The product of failed protein synthesis
23. A common genetic variation which causes a change in the amino acid sequence in the structure of
hemoglobin leads to the disease ____.
a.
diabetes
b.
marasmus
c.
phenylketonuria
d.
sickle-cell anemia
e.
hemolytic anemia
24. What type of protein would the body make in order to heal a wound?
a.
Ferritin
b.
Albumin
c.
Collagen
d.
Hemoglobin
e.
Enzyme
25. What is the relationship between body proteins and water?
a.
Proteins attract water.
b.
Water attracts proteins.
c.
Water degrades proteins.
d.
Proteins form polymers of water.
e.
Proteins repel water.
26. What function does a buffer perform?
a.
It helps emulsify fats.
b.
It helps maintain a constant pH.
c.
It facilitates chemical reactions.
d.
It helps protect against plaque buildup.
e.
It prevents degradation of proteins.
27. How do sodium and potassium travel into and out of cells?
a.
Antidiuretic hormone transports potassium and prodiuretic hormone carries sodium.
b.
Specific transport proteins in the blood deliver the minerals to the cell cytoplasm.
c.
The balance of insulin and glucagon determines the movement of these minerals into and
out of cells.
d.
Transport proteins within the cell membrane pick up and release the minerals across the
membrane.
e.
A negative feedback loop uses blood glucose levels for transfer.
28. What is opsin?
a.
An antigen
b.
An antibody
c.
A light-sensitive protein
d.
A blood transport protein
e.
A sterol
29. Which of the following describes the structure of an antibody?
a.
Tripeptide
b.
Small nucleic acid
c.
Huge protein molecule
d.
Large peptide molecule
e.
Location of carbons
30. Which substance is involved in the clotting of blood?
a.
Opsin
b.
Fibrin
c.
Collagen
d.
Transferrin
e.
Thyroxin
31. Which of the following may be used to determine protein utilization?
a.
Calorimetry
b.
Nitrogen balance
c.
Amino acid pool
d.
Supplementary value
e.
Body mass index
32. When nitrogen taken into the body exceeds nitrogen losses, we say the person is in ____.
a.
a healthy state
b.
nitrogen equilibrium
c.
positive nitrogen balance
d.
negative nitrogen balance
e.
nitrogen homeostasis
33. What is the amino acid pool?
a.
The total amino acid content derived from a 24-hour dietary intake
b.
A measure of the circulating essential amino acid levels available for protein synthesis
c.
The total amount of free amino acids in the circulation destined for deamination and
excretion
d.
A mix of essential and nonessential amino acids derived from protein breakdown and
dietary protein intake
e.
The essential and nonessential amino acids from dietary intake that are available for
protein synthesis
34. What is the usual state of nitrogen balance for healthy infants, children, and pregnant women?
a.
Equilibrium
b.
Metabolic
c.
Positive
d.
Negative
e.
Homeostatic
35. What amino acid is used to synthesize the neurotransmitter serotonin and the vitamin niacin?
a.
Glycine
b.
Tyrosine
c.
Methionine
d.
Tryptophan
e.
Valine
36. What is meant by protein turnover?
a.
Nitrogen equilibrium
b.
The antibody-antigen complex
c.
The synthesis and degradation of body proteins
d.
The secondary structure of proteins that initiates folding
e.
The failure of the body to form needed proteins
37. When amino acids are deaminated, the immediate products are ammonia and often a ____.
a.
uric acid
b.
keto acid
c.
folic acid
d.
gluco acid
e.
phyto acid
38. Protein sparing in the body is best achieved when a person ingests ____.
a.
proteins of plant origin only
b.
proteins of animal origin only
c.
adequate levels of carbohydrate and fat
d.
mixed protein sources on alternate days
e.
consumes a very low fat diet
39. Approximately how much urea (g) can be produced daily by the average adult?
a.
5 g
b.
50 g
c.
100 g
d.
250 g
e.
500 g
40. What is the most likely side effect of a high-protein, low-carbohydrate diet?
a.
Diarrhea
b.
Increased thirst
c.
Nitrogen toxicity
d.
Increased water retention in the body
e.
Weight gain
41. What is a consequence of excess protein intake?
a.
Decreased excretion of calcium
b.
Decreased size of the liver and kidneys
c.
Increased production and excretion of urea
d.
Increased protein storage by the liver and kidneys
e.
Improved renal functioning
42. What is the process whereby an amino group is combined with a keto acid to form an amino acid?
a.
Deamination
b.
Ureagenesis
c.
Transamination
d.
Ammoniogenesis
e.
Ketoacidosis
43. In the metabolism of amino acids for energy, what is the fate of the amino group?
a.
Excreted as urea
b.
Burned for energy
c.
Stored in the liver
d.
Converted to glucose
e.
Recycled in the liver
44. What is the most likely reason for a person to have abnormally high blood ammonia levels?
a.
Liver dysfunction
b.
Kidney dysfunction
c.
Protein intake twice the RDA
d.
Protein intake one-tenth the RDA
e.
Hyperstimulation of the immune system
45. What is the most likely reason for having an abnormally high blood urea level?
a.
Liver dysfunction
b.
Kidney dysfunction
c.
Protein intake twice the RDA
d.
Protein intake one-tenth the RDA
e.
Hyperstimulation of the immune system
46. What is the percent digestibility of most plant proteins?
a.
30–50
b.
50–60
c.
60–70
d.
70–90
e.
90–99
47. What is the percent digestibility of most animal proteins?
a.
50–59
b.
60–69
c.
70–79
d.
80–89
e.
90–99
48. Which of the following food proteins has the best assortment of essential amino acids for the human
body?
a.
Egg
b.
Rice
c.
Corn
d.
Gelatin
e.
Soy
49. Which animal-derived protein is classified as a poor-quality protein?
a.
Fish
b.
Cheese
c.
Gelatin
d.
Turkey
e.
Fatty fish
50. If the diet is lacking an essential amino acid, what will be the likely course of action?
a.
Body cells will synthesize it.
b.
Protein synthesis will be limited.
c.
Health will not be affected as long as other nutrients are adequate.
d.
Proteins will be made but they will lack that particular amino acid.
e.
Massive muscle wasting will occur.
51. What is a “limiting” amino acid in a protein?
a.
A nonessential amino acid present in high amounts, which inhibits protein synthesis
b.
An amino acid of the wrong structure to be utilized for protein synthesis efficiently
c.
An essential amino acid present in insufficient quantity for body protein synthesis to take
place
d.
An amino acid that limits the absorption of other essential amino acids by competing with
them for transport sites within the GI tract
e.
An amino acid that has the paradoxical effect of causing catabolism
52. Which statement characterizes the protein nutrition in vegetarians?
a.
Vegetarians in general must practice complementary protein nutrition.
b.
Most vegetarians should consume gelatin to ensure adequate tryptophan intake.
c.
Healthy vegetarians typically consume protein sources of very high digestibility.
d.
Most vegetarians eating a variety of foods need not balance essential amino acid intake at
each meal.
e.
A significant majority of vegetarians experience clinically significant protein malnutrition.
53. In general, the protein quality in grains would be most improved by the addition of a plant protein rich
in ____.
a.
lysine
b.
tryptophan
c.
phenylalanine
d.
glutamic acid
e.
methionine
54. In general, the protein quality of legumes would be most improved by the addition of a plant protein
rich in ____.
a.
lysine
b.
tyrosine
c.
methionine
d.
glutamic acid
e.
phenylalanine
55. Excessive amounts of homocysteine in the blood are thought to increase the risk for ____.
a.
cancer
b.
diabetes
c.
heart disease
d.
protein-energy malnutrition
e.
hypothyroidism
56. Which amino acid has been reported to lower blood pressure and reduce homocysteine levels?
a.
Arginine
b.
Cysteine
c.
Tryptophan
d.
Phenylalanine
e.
Methionine
57. Which statement describe a relationship between protein/amino acids and heart disease?
a.
Substituting soy protein for animal protein raises blood cholesterol levels.
b.
High blood levels of the amino acid arginine are a risk factor for atherosclerosis.
c.
High levels of homocysteine in food promote elevation of blood low-density lipoproteins.
d.
Elevated blood homocysteine levels are associated with smoking cigarettes and drinking
alcohol.
e.
High blood levels of phenylalanine dampen inflammatory responses, reducing risk of heart
disease.
58. Which statement describes an association between protein intake and kidney function?
a.
Low-protein diets increase the risk for kidney stone formation.
b.
Restricting protein intake may slow the progression of kidney disease.
c.
High protein intakes over the long term represent a risk factor for kidney disease.
d.
Liberal protein intakes result in high urea production, which increases the long-term
efficiency of the kidneys.
e.
High protein diets in childhood protect the kidneys from age- and illness-associated
damage.
59. What is the actual ratio of calcium to protein intake (mg to g) for most U.S. women?
a.
3:1
b.
9:1
c.
13:1
d.
21:1
e.
36:1
60. What would be the primary principle of wise diet planning as related to protein nutrition?
a.
Variety
b.
Moderation
c.
Nutrient density
d.
kCalorie control
e.
Balance
61. What is a feature of the protein RDA?
a.
The recommendations are generous.
b.
The recommendations are highest proportionately for adult males.
c.
The recommendations are established at 8 grams per kilogram of ideal body weight.
d.
The recommendations assume that dietary protein is from animal sources only.
e.
The recommendations fail to consider the need to replace damaged tissues.
62. Which of the following is an assumption made in the formulation of the RDA for protein?
a.
Dietary protein is of high quality only.
b.
Dietary protein is of animal origin only.
c.
Dietary carbohydrate and fat intakes are adequate.
d.
Dietary protein should represent 12% of total energy.
e.
Dietary protein needs are lower in infants and children.
63. Which of the following is a feature of whey protein?
a.
It is a high-priced protein supplement.
b.
It is chemically extracted from gelatin.
c.
It is a waste product of cheese production.
d.
It enhances athletic performance when regularly consumed.
e.
It is no longer legal to use in over-the-counter products