Question 1

In which of the following conditions is Hb A&#8322; elevated?&#10;A)alpha thalassemia trait&#10;B)beta thalassemia trait&#10;C)Hb SC disease&#10;D)HB S trait

Accepted Answer

The major laboratory indicator of beta thalassemia trait is an increased relative percentage of Hb A₂.Hb F may also be elevated.

Question 2

The reaction of iron in hemoglobin binding to oxygen is known as a/an _________ reaction.&#10;A)oxidation&#10;B)reduction&#10;C)oxygenation&#10;D)complexation

Accepted Answer

Heme iron atoms bind to oxygen by an oxygenation reaction.Since the iron remains in the ferrous state during the reaction, oxygen binding to heme is not an oxidation reaction.

Question 3

It has been observed that the organism causing __________ fails to grow in Hb S-containing red blood cells.&#10;A)meningitis&#10;B)rubella&#10;C)syphilis&#10;D)malaria

Accepted Answer

Individuals heterozygous for Hb S appear to be protected from malaria because Plasmodium organisms fail to grow in Hb S-containing red blood cells.

Question 4

Which of the following laboratory findings would be expected when a hemoglobinopathy causes the oxygen dissociation curve to shift to the left?&#10;A)hypochromic microcytic red blood cells&#10;B)erythrocytosis&#10;C)acidosis&#10;D)increased serum iron and TIBC

Accepted Answer

Some amino-acid substitutions forming variant hemoglobins result in high hemoglobin affinity for oxygen and tissue hypoxia.This results in a shift to the left of the oxygen dissociation curve.Tissue hypoxia will cause the kidney to increase erythropoietin production to stimulate increased hemoglobin and red blood cell production.The increased red blood cell production coupled with the red cells already available will result in erythrocytosis.

Question 5

Which of the following provides the primary advantage of Hb F for the developing fetus?&#10;A)Hb F has a higher oxygen affinity than Hb A.&#10;B)Hb F has a lower oxygen affinity than Hb A.&#10;C)Hb F is resistant to oxidation to methemoglobin.&#10;D)Hb F is resistant to alkali denaturation.

Accepted Answer

The advantage of Hb F for the developing fetus is that Hb F has a higher oxygen affinity than Hb A.This characteristic facilitates oxygen transport across the placental barrier.The reason for the higher affinity is that Hb F binds 2,3-BPG to a lesser degree than Hb A because of the presence of γ-chains.

Question 6

The formation of hemichromes has been considered an indicator of:&#10;A)hemoglobin glycosylation&#10;B)hemoglobin oxygenation&#10;C)hemoglobin deoxygenation&#10;D)hemoglobin denaturation

Accepted Answer

Hemichromes are greenish ferric compounds with characteristic spectral absorption profiles.Hemichromes result from oxidative changes to heme (Fe²⁺ to Fe³⁺) and to the protein of hemoglobin, potentially altering the binding of heme to the protein.The result is the breakdown of hemoglobin, which forms inclusions on the interior surface of red-blood-cell membranes known as Heinz bodies.Heinz bodies result in lysis of red blood cells.

Question 7

A hexokinase deficiency would result in a shift to the ______of the oxygen dissociation curve, and a pyruvate kinase deficiency would result in a s(answer format: blank 1, blank 2)&#10;A)right, right&#10;B)right, left&#10;C)left, left&#10;D)left, right

Accepted Answer

A hexokinase deficiency will result in a deficiency of 2,3-BPG in the red blood cell, which would shift the oxygen dissociation curve to the left.The hexokinase enzyme appears in the glycolytic pathway before the production of 2,3-BPG.A pyruvate kinase deficiency would result in a build up of 2,3-BPG, resulting in a shift of the oxygen dissociation curve to the right.The pyruvate kinase enzyme appears in the glycolytic pathway after the production of 2,3-BPG.

Question 8

A shift of the oxygen dissociation curve to the left indicates:&#10;A)increased oxygen-binding capacity of hemoglobin at a given oxygen tension and increased oxygen release to tissues&#10;B)increased oxygen-binding capacity of hemoglobin at a given oxygen tension and decreased oxygen release to tissues&#10;C)decreased oxygen-binding capacity of hemoglobin at a given oxygen tension and decreased oxygen release to tissues&#10;D)decreased oxygen-binding capacity of hemoglobin at a given oxygen tension and increased oxygen release to tissues

Accepted Answer

A shift of the oxygen dissociation curve to the left results in increased oxygen-binding capacity of hemoglobin at a given oxygen tension because of an increased affinity of hemoglobin for oxygen.This increased affinity of hemoglobin for oxygen will result in decreased oxygen release to tissues.Factors that can cause a shift to the left include increased pH, decreased temperature, and decreased 2,3-BPG levels.

Question 9

Hb S results from the substitution of ______ for glutamic acid in the beta chain of hemoglobin.The ______ form of Hb S is the form that has the potential to polymerize to produce sickle cells.&#10;A)valine, deoxygenated&#10;B)histidine, oxygenated&#10;C)lysine, deoxygenated&#10;D)tyrosine, oxygenated

Accepted Answer

Hb S results from the substitution of valine for glutamic acid in the beta chain of hemoglobin.The deoxygenated form of Hb S has the potential to polymerize with red blood cells, forming long fibers that result in the sickle-cell shape.The oxygenated form of Hb S does not polymerize.

Question 10

Oxygen binds directly to which component of hemoglobin?&#10;A)the four pyrrole nitrogens in the core of protoporphyrin&#10;B)the ferrous iron in the core of protoporphyrin&#10;C)the ferric iron in the core of protoporphyrin&#10;D)2,3-BPG bound in the central cavity of the hemoglobin tetramer

Accepted Answer

Iron in the center of the protoporphyrin ring is in the ferrous (Fe²⁺) state.The heme iron has six valency bonds, four of which are occupied by the four pyrrole nitrogens.The fifth iron valency attaches heme to globin, and the sixth iron valency is available for reversible bonding with oxygen.

Question 11

The relationship between partial pressure of oxygen and percent hemoglobin saturation with oxygen is described by a ______ curve.This curve shape results from the fact that ______.&#10;A)hyperbolic, each heme molecule is oxygenated independently&#10;B)hyperbolic, oxygenation of one heme group increases the oxygen affinity of others&#10;C)sigmoid, each heme molecule is oxygenated independently&#10;D)sigmoid, oxygenation of one heme group increases the oxygen affinity of others

Accepted Answer

The answer of The relationship between partial pressure of oxygen...

Question 12

M-hemoglobins are derived from:&#10;A)methemoglobin&#10;B)sulfhemoglobin&#10;C)carboxyhemoglobin&#10;D)glycosylated hemoglobin A

Accepted Answer

The answer of M-hemoglobins are derived from:&#10;A)methemoglobin&#10;B)sulfhemoglobin&#10;C)carboxyhemoglobin&#10;D)glycosylated hemoglobin A...

Question 13

Which of the following characteristics differentiates methemoglobin and sulfhemoglobin?&#10;A)the production of anoxia and cyanosis&#10;B)the ability to be reduced back to hemoglobin&#10;C)the ability to transport oxygen&#10;D)both a and b

Accepted Answer

The answer of Which of the following characteristics differentiates methemoglobin...

Question 14

The level of 2,3-biphosphoglycerate (2,3-BPG) exerts a significant influence on the oxygen dissociation curve.The level of 2,3-BPG production is regulated by which of the following glycolytic enzymes?&#10;A)lactate dehydrogenase&#10;B)phosphofructokinase&#10;C)glucose-6-phosphatase&#10;D)beta-hydroxybutyrate dehydrogenase

Accepted Answer

The answer of The level of 2,3-biphosphoglycerate (2,3-BPG) exerts a...

Question 15

The problem with methemoglobin is:&#10;A)it cannot bind oxygen reversibility.&#10;B)it has a higher affinity for carbon monoxide than carbon dioxide.&#10;C)it has a much higher affinity for carbon monoxide than oxygen.&#10;D)it has a much higher affinity for carbon dioxide than oxygen.

Accepted Answer

The answer of The problem with methemoglobin is:&#10;A)it cannot bind...

Question 16

Which of the following causes hemolysis in association with thalassemia?&#10;A)the free iron available in the red cell due to a deficiency of protoporphyrin&#10;B)the presence of an excess of one globin chain pair&#10;C)the presence of hemichromes&#10;D)the free heme available in the red blood cell due to the presence of variant hemoglobins

Accepted Answer

The answer of Which of the following causes hemolysis in...

Question 17

Which of the following correctly contrasts the interactions of oxygen and carbon monoxide with hemoglobin?
1)Oxygen combines more rapidly with hemoglobin than does carbon monoxide.
2)Oxygen is released more slowly from hemoglobin than is carbon monoxide.
3)Oxygen has less affinity for hemoglobin than does carbon monoxide.

A)1, 2, 3
B)1, 2
C)2, 3
D)1, 3

Accepted Answer

The answer of Which of the following correctly contrasts the...

Question 18

Synthesis of hemoglobin is normally stimulated by hypoxia causing the ______ to produce ______.&#10;A)hypothalamus, hemopexin&#10;B)adrenal gland, haptoglobin&#10;C)kidneys, erythropoietin&#10;D)lungs, angiotensin

Accepted Answer

The answer of Synthesis of hemoglobin is normally stimulated by...

Deck 40: Hemoglobin