RBC Flashcards by Mind Med

The normal physiological pH range of human blood is best described as:
A. 7.00–7.20
B. 7.25–7.35
C. 7.35–7.45
D. 7.45–7.55

C. 7.35–7.45

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Which biochemical parameter primarily reflects the buffering capacity of blood?
A. Plasma albumin
B. Hemoglobin concentration
C. Bicarbonate concentration
D. Plasma chloride

C. Bicarbonate concentration

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The bluish or purplish appearance of venous blood is primarily due to:
A. Increased bilirubin
B. Reduced hemoglobin oxygenation
C. Increased methemoglobin
D. Elevated plasma proteins

B. Reduced hemoglobin oxygenation

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A low hematocrit most directly suggests:
A. Increased erythrocyte production
B. Dehydration
C. Reduced erythrocyte mass or increased destruction
D. Increased plasma protein synthesis

C. Reduced erythrocyte mass or increased destruction

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A falsely elevated hematocrit may occur in which condition?
A. Iron deficiency anemia
B. Acute hemorrhage
C. Dehydration
D. Hemolytic anemia

C. Dehydration

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Which plasma protein is primarily responsible for maintaining oncotic pressure?
A. Fibrinogen
B. Albumin
C. Gamma globulin
D. Transferrin

B. Albumin

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Albumin is synthesized primarily in the:
A. Bone marrow
B. Spleen
C. Liver
D. Kidney

C. Liver

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In addition to oncotic pressure regulation, albumin serves which biochemical role?
A. Catalysis of clot formation
B. Antibody production
C. Transport of fatty acids and lipid-soluble substances
D. Oxygen transport

C. Transport of fatty acids and lipid-soluble substances

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Which plasma protein is directly involved in clot formation?
A. Albumin
B. Alpha globulin
C. Gamma globulin
D. Fibrinogen

D. Fibrinogen

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Gamma globulins are biochemically classified as:
A. Transport proteins
B. Structural proteins
C. Enzymes
D. Immunoglobulins

D. Immunoglobulins

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Which electrolytes play a major role in maintaining acid–base balance in plasma?
A. Na⁺ and K⁺
B. Ca²⁺ and Mg²⁺
C. Cl⁻ and HCO₃⁻
D. PO₄³⁻ and SO₄²⁻

C. Cl⁻ and HCO₃⁻

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Mature erythrocytes are best described as:
A. Nucleated, spherical cells
B. Anucleated, biconcave discs
C. Anucleated, spherical cells
D. Nucleated, discoid cells

B. Anucleated, biconcave discs

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The biconcave shape of RBCs primarily enhances:
A. ATP production
B. DNA synthesis
C. Gas exchange efficiency
D. Protein synthesis

C. Gas exchange efficiency

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The zone of central pallor in RBCs represents:
A. Absence of hemoglobin
B. Presence of the nucleus
C. The biconcave depression
D. Membrane protein aggregation

C. The biconcave depression

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The average lifespan of a red blood cell is:
A. 30 days
B. 60 days
C. 90 days
D. 120 days

D. 120 days

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he absence of mitochondria in mature RBCs is biochemically significant because it:
A. Prevents oxidative damage
B. Allows more space for hemoglobin
C. Enables aerobic respiration
D. Enhances protein synthesis

B. Allows more space for hemoglobin

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The mean corpuscular volume (MCV) of a normal RBC is approximately:
A. 60 fL
B. 75 fL
C. 90 fL
D. 110 fL

C. 90 fL

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RBC membrane deformability is MOST dependent on:
A. Cholesterol content alone
B. Phospholipid saturation
C. Cytoskeletal protein organization
D. Glycoprotein carbohydrate chains

C. Cytoskeletal protein organization

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Integral membrane proteins differ from peripheral membrane proteins in that integral proteins:
A. Are loosely attached to the membrane surface
B. Span the lipid bilayer
C. Are cytosolic enzymes
D. Do not interact with lipids

B. Span the lipid bilayer

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Band 3 protein functions primarily as a:
A. Sodium-potassium pump
B. Calcium channel
C. Bicarbonate–chloride exchanger
D. Glucose transporter

C. Bicarbonate–chloride exchanger

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At the tissue level, Band 3 mediates:
A. Chloride efflux and bicarbonate influx
B. Bicarbonate efflux and chloride influx
C. Sodium influx
D. Proton extrusion

B. Bicarbonate efflux and chloride influx

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Glycophorin A contributes to RBC function by:
A. Transporting glucose
B. Providing a negative surface charge
C. Anchoring spectrin
D. Binding oxygen

B. Providing a negative surface charge

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Polymorphisms in glycophorin A form the biochemical basis of:
A. ABO blood groups
B. Rh blood groups
C. MN blood group system
D. Kell blood group system

C. MN blood group system

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The most abundant protein in the RBC cytoskeleton is:
A. Ankyrin
B. Actin
C. Spectrin
D. Band 4.1

C. Spectrin

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Spectrin is composed of: A. Identical monomers B. Alpha and beta polypeptide chains C. Four globin-like subunits D. Actin polymers

B. Alpha and beta polypeptide chains

Ankyrin’s primary biochemical role is to: A. Bind oxygen B. Anchor spectrin to Band 3 C. Catalyze ATP synthesis D. Regulate ion transport

B. Anchor spectrin to Band 3

Protein 4.1 contributes to RBC membrane stability by: A. Binding hemoglobin B. Anchoring the cytoskeleton to glycophorin C. Transporting chloride ions D. Acting as a kinase

B. Anchoring the cytoskeleton to glycophorin

Disruption of spectrin–ankyrin interactions would MOST likely result in: A. Increased ATP production B. Loss of RBC deformability C. Increased oxygen affinity D. Enhanced membrane rigidity without consequence

B. Loss of RBC deformability

Glucose enters mature red blood cells primarily via: A. Active transport using ATP B. Sodium-dependent cotransport C. Facilitated diffusion through GLUT-1 D. Endocytosis

C. Facilitated diffusion through GLUT-1

Mature erythrocytes rely exclusively on anaerobic glycolysis because they: A. Have defective mitochondria B. Have low oxygen tension C. Lack mitochondria entirely D. Cannot utilize fatty acids

C. Lack mitochondria entirely

Which molecule serves as the sole energy substrate for mature RBCs? A. Fatty acids B. Amino acids C. Glucose D. Lactate

C. Glucose

The Embden–Meyerhof pathway in RBCs primarily functions to: A. Generate NADPH B. Produce ATP for membrane integrity C. Synthesize hemoglobin D. Detoxify reactive oxygen species

B. Produce ATP for membrane integrity

Glycolysis in RBCs is also referred to as: A. Aerobic glycolysis B. Oxidative phosphorylation C. Anaerobic glycolysis D. Gluconeogenesis

C. Anaerobic glycolysis

One molecule of glucose metabolized through EMP in RBCs yields: A. 4 ATP (net) B. 2 ATP (net) C. 6 ATP (net) D. 8 ATP (net)

B. 2 ATP (net)

The conversion of glucose to lactate in RBCs produces: A. 2 molecules of pyruvate B. 4 molecules of ATP C. 2 molecules of lactate D. No ATP

C. 2 molecules of lactate

The net ATP yield of anaerobic glycolysis is limited because: A. NADH cannot be regenerated B. ATP is consumed by lactate dehydrogenase C. Oxidative phosphorylation is absent D. Glucose uptake is inefficient

C. Oxidative phosphorylation is absent

Which reaction ensures continued glycolytic flux in RBCs? A. Glucose → Glucose-6-phosphate B. Pyruvate → Lactate C. Fructose-6-phosphate → Fructose-1,6-bisphosphate D. 1,3-BPG → 3-PG

B. Pyruvate → Lactate

Lactate dehydrogenase is critical in RBC metabolism because it: A. Generates ATP B. Oxidizes lactate C. Regenerates NAD⁺ from NADH D. Produces NADPH

C. Regenerates NAD⁺ from NADH

Excess lactate production can lead to: A. Metabolic alkalosis B. Respiratory alkalosis C. Lactic acidosis D. Ketoacidosis

C. Lactic acidosis

Which tissue relies on anaerobic glycolysis even in the well-fed state? A. Liver B. Skeletal muscle C. Mature erythrocytes D. Brain

C. Mature erythrocytes

All of the following tissues depend heavily on anaerobic glycolysis EXCEPT: A. Cornea B. Lens C. Renal medulla D. Cardiac muscle

D. Cardiac muscle

The inability of these tissues to perform oxidative phosphorylation is due to: A. High oxygen demand B. Low enzyme concentration C. Absence or scarcity of mitochondria D. Inadequate glucose supply

C. Absence or scarcity of mitochondria

The primary biochemical role of the HMP shunt in RBCs is to: A. Generate ATP B. Produce NADPH C. Produce lactate D. Regenerate NAD⁺

B. Produce NADPH

NADPH generated by the HMP shunt is required for: A. ATP synthesis B. Hemoglobin synthesis C. Reduction of oxidized glutathione D. Lactate formation

C. Reduction of oxidized glutathione

The HMP shunt protects RBCs primarily against damage from: A. Carbon dioxide B. Hydrogen peroxide C. Nitric oxide D. Oxygen

B. Hydrogen peroxide

Which enzyme initiates the HMP shunt and is rate-limiting? A. Glucose-6-phosphate isomerase B. Glucose-6-phosphate dehydrogenase C. Glutathione reductase D. Glutathione peroxidase

B. Glucose-6-phosphate dehydrogenase

Reduced glutathione (GSH) detoxifies hydrogen peroxide by: A. Direct oxidation to oxygen B. Conversion to water and oxygen C. Binding peroxide irreversibly D. Reducing NADP⁺

B. Conversion to water and oxygen

During peroxide detoxification, glutathione becomes: A. Reduced B. Phosphorylated C. Oxidized (GSSG) D. Acetylated

C. Oxidized (GSSG)

The glutathione system consists of all EXCEPT: A. Reduced glutathione (GSH) B. Oxidized glutathione (GSSG) C. Glutathione reductase D. Superoxide dismutase

D. Superoxide dismutase

Glutathione reductase requires which cofactor to function? A. NADH B. NADPH C. FADH₂ D. ATP

B. NADPH

Failure of the glutathione system leads to: A. Increased ATP production B. Enhanced membrane rigidity C. Oxidative damage to proteins and lipids D. Increased oxygen affinity

C. Oxidative damage to proteins and lipids

Oxidative damage to the RBC membrane results in: A. Increased deformability B. Hemolysis C. Enhanced oxygen delivery D. Increased lifespan

B. Hemolysis

Glucose-6-phosphate dehydrogenase deficiency primarily impairs: A. ATP production B. NADH regeneration C. NADPH production D. Lactate formation

C. NADPH production

In G6PD deficiency, reduced glutathione levels are: A. Increased B. Normal C. Decreased D. Unaffected

C. Decreased

Insufficient reduced glutathione leads to: A. Increased membrane fluidity B. Hemoglobin denaturation C. Increased glycolysis D. Increased NADPH

B. Hemoglobin denaturation

Denatured hemoglobin aggregates formed in G6PD deficiency are called: A. Howell–Jolly bodies B. Heinz bodies C. Basophilic stippling D. Target cells

B. Heinz bodies

Heinz bodies most directly cause hemolysis by: A. Blocking oxygen binding B. Increasing RBC rigidity C. Inhibiting ATP synthesis D. Activating complement

B. Increasing RBC rigidity

Which of the following can precipitate hemolysis in G6PD-deficient individuals? A. Vitamin C B. Fava beans C. Glucose D. Iron supplements

B. Fava beans

The anemia associated with G6PD deficiency is best classified as: A. Megaloblastic anemia B. Microcytic hypochromic anemia C. Hereditary nonspherocytic hemolytic anemia D. Iron-deficiency anemia

C. Hereditary nonspherocytic hemolytic anemia

RBCs are especially vulnerable in G6PD deficiency because they: A. Cannot synthesize new proteins B. Lack antioxidant enzymes C. Cannot generate NADH D. Rely solely on fatty acids

A. Cannot synthesize new proteins

Which pathway directly generates ATP in RBCs? A. HMP shunt B. Glutathione system C. Embden–Meyerhof pathway D. Cytochrome b5 pathway

C. Embden–Meyerhof pathway

Which pathway is primarily protective rather than energy-producing? A. EMP B. HMP shunt C. Rapoport–Luebering pathway D. Glycolysis

B. HMP shunt

A deficiency in which pathway most directly increases oxidative stress? A. EMP B. HMP shunt C. Rapoport–Luebering pathway D. Lactate fermentation

B. HMP shunt

The Rapoport–Luebering pathway is unique to: A. All cells B. Muscle cells C. Red blood cells D. Liver cells

C. Red blood cells

The primary function of the Rapoport–Luebering pathway is to: A. Generate ATP B. Generate NADPH C. Regulate hemoglobin oxygen affinity D. Detoxify peroxides

C. Regulate hemoglobin oxygen affinity

The Rapoport–Luebering pathway diverts which glycolytic intermediate? A. Glucose-6-phosphate B. Fructose-6-phosphate C. 1,3-bisphosphoglycerate D. Pyruvate

C. 1,3-bisphosphoglycerate

1,3-bisphosphoglycerate is converted into 2,3-bisphosphoglycerate by: A. Phosphoglycerate kinase B. Bisphosphoglycerate mutase C. Lactate dehydrogenase D. Pyruvate kinase

B. Bisphosphoglycerate mutase

The conversion of 2,3-BPG back to glycolysis yields: A. 3-phosphoglycerate B. 2-phosphoglycerate C. Pyruvate D. Lactate

A. 3-phosphoglycerate

Which enzyme converts 2,3-BPG into 3-phosphoglycerate? A. Enolase B. Bisphosphoglycerate phosphatase C. Phosphoglycerate kinase D. Aldolase

B. Bisphosphoglycerate phosphatase

Activation of the Rapoport–Luebering pathway results in: A. Increased ATP production B. Decreased ATP yield C. Increased NADH production D. Increased lactate formation

B. Decreased ATP yield

2,3-BPG binds preferentially to: A. Oxyhemoglobin B. Alpha chains of hemoglobin C. Deoxyhemoglobin D. Methemoglobin

C. Deoxyhemoglobin

The binding site of 2,3-BPG on hemoglobin is: A. Heme iron B. Alpha-beta interface C. Central cavity between beta chains D. N-terminal alpha chains

C. Central cavity between beta chains

Binding of 2,3-BPG to hemoglobin causes: A. Increased oxygen affinity B. Leftward shift of the O₂ dissociation curve C. Stabilization of the T (tense) state D. Conversion to methemoglobin

C. Stabilization of the T (tense) state

Increased levels of 2,3-BPG result in: A. Reduced oxygen delivery to tissues B. Enhanced oxygen release to tissues C. Increased hemoglobin synthesis D. Decreased lactate production

B. Enhanced oxygen release to tissues

A rightward shift of the oxygen dissociation curve indicates: A. Increased Hb–O₂ affinity B. Decreased Hb–O₂ affinity C. Increased oxygen saturation D. Reduced tissue oxygen delivery

B. Decreased Hb–O₂ affinity

All of the following increase 2,3-BPG levels EXCEPT: A. Chronic hypoxia B. High altitude C. Anemia D. Carbon monoxide poisoning

D. Carbon monoxide poisoning

Fetal hemoglobin (HbF) has lower affinity for 2,3-BPG because: A. It lacks beta chains B. It has gamma chains instead of beta chains C. It lacks heme D. It is monomeric

B. It has gamma chains instead of beta chains

The reduced 2,3-BPG binding of HbF results in: A. Decreased oxygen affinity B. Enhanced oxygen transfer from mother to fetus C. Increased ATP production D. Increased hemoglobin degradation

B. Enhanced oxygen transfer from mother to fetus

Bypassing phosphoglycerate kinase via the Rapoport–Luebering pathway leads to loss of: A. NADPH B. 1 ATP per glucose C. 2 ATP per glucose D. 4 ATP per glucose

B. 1 ATP per glucose

The ATP sacrifice in the Rapoport–Luebering pathway is biochemically justified because it: A. Increases glucose uptake B. Enhances tissue oxygenation C. Prevents oxidative stress D. Produces NADPH

B. Enhances tissue oxygenation

Functional hemoglobin requires iron in which oxidation state? A. Fe³⁺ B. Fe²⁺ C. Fe⁰ D. Fe⁴⁺

B. Fe²⁺

Methemoglobin contains iron in the: A. Ferrous state B. Ferric state C. Zero-valent state D. Reduced state

B. Ferric state

Methemoglobin is incapable of: A. Binding carbon dioxide B. Binding oxygen C. Transporting protons D. Interacting with 2,3-BPG

B. Binding oxygen

The primary enzyme responsible for reducing methemoglobin back to hemoglobin is: A. Glutathione reductase B. Cytochrome b5 reductase C. Catalase D. Superoxide dismutase

B. Cytochrome b5 reductase

Cytochrome b5 reductase utilizes which reducing equivalent? A. NADPH B. FADH₂ C. NADH D. ATP

C. NADH

The physiological importance of cytochrome b5 reductase is to: A. Generate ATP B. Prevent oxidative membrane damage C. Maintain hemoglobin in the ferrous state D. Produce NADPH

C. Maintain hemoglobin in the ferrous state

Deficiency of cytochrome b5 reductase leads to: A. G6PD deficiency B. Sickle cell anemia C. Methemoglobinemia D. Thalassemia

C. Methemoglobinemia

Patients with methemoglobinemia may present with: A. Bright red blood B. Cyanosis unresponsive to oxygen therapy C. Increased hemoglobin concentration D. Jaundice only

B. Cyanosis unresponsive to oxygen therapy

Exposure to which agent can precipitate methemoglobinemia? A. Nitrates and nitrites B. Fava beans C. Iron deficiency D. Vitamin B₁₂

A. Nitrates and nitrites

Increased 2,3-BPG levels would be MOST beneficial in which condition? A. Carbon monoxide poisoning B. Severe anemia C. Polycythemia vera D. Iron overload

B. Severe anemia

Carbon monoxide poisoning shifts the oxygen dissociation curve: A. To the right B. To the left C. Without change D. Biphasically

B. To the left

CO poisoning decreases oxygen delivery because it: A. Reduces ATP synthesis B. Increases 2,3-BPG binding C. Increases Hb oxygen affinity D. Oxidizes heme iron

C. Increases Hb oxygen affinity

Which combination BEST explains cyanosis with normal PaO₂? A. G6PD deficiency B. Iron deficiency anemia C. Methemoglobinemia D. Thalassemia minor

C. Methemoglobinemia

Heme is best described as: A. A protein containing iron B. A tetrapyrrole ring with ferrous iron C. A globular oxygen-binding protein D. A carbohydrate-iron complex

B. A tetrapyrrole ring with ferrous iron

The iron present in functional heme is in the: A. Ferric (Fe³⁺) state B. Ferrous (Fe²⁺) state C. Metallic (Fe⁰) state D. Mixed valence state

B. Ferrous (Fe²⁺) state

The porphyrin ring of heme is formed by: A. Three pyrrole rings B. Four pyrrole rings linked by methene bridges C. Five pyrrole rings D. Two fused rings

B. Four pyrrole rings linked by methene bridges

Protoporphyrin IX becomes heme after insertion of: A. Zinc B. Copper C. Iron D. Magnesium

C. Iron

Heme biosynthesis occurs primarily in: A. Cytosol only B. Mitochondria only C. Both mitochondria and cytosol D. Nucleus and cytosol

C. Both mitochondria and cytosol

The final step of heme synthesis also occurs in the: A. Cytosol B. Golgi apparatus C. Endoplasmic reticulum D. Mitochondria

D. Mitochondria

The first reaction in heme synthesis condenses: A. Glycine and acetyl-CoA B. Glycine and succinyl-CoA C. Alanine and succinyl-CoA D. Glycine and pyruvate

B. Glycine and succinyl-CoA

ALA synthase requires which cofactor? A. Biotin B. Vitamin B₁₂ C. Pyridoxal phosphate (vitamin B₆) D. Folic acid

C. Pyridoxal phosphate (vitamin B₆)

The rate-limiting enzyme of heme biosynthesis is: A. ALA dehydratase B. Ferrochelatase C. Porphobilinogen synthase D. ALA synthase

D. ALA synthase

Heme synthesis is regulated primarily at: A. Porphyrin ring formation B. Iron insertion C. ALA synthase D. Heme degradation

C. ALA synthase

Heme exerts feedback inhibition on: A. Ferrochelatase B. ALA synthase C. ALA dehydratase D. Uroporphyrinogen III synthase

B. ALA synthase

Two molecules of ALA condense to form: A. Uroporphyrinogen B. Coproporphyrinogen C. Porphobilinogen D. Protoporphyrin IX

C. Porphobilinogen

The enzyme catalyzing this reaction is also known as: A. ALA synthase B. Porphobilinogen deaminase C. ALA dehydratase D. Ferrochelatase

C. ALA dehydratase

ALA dehydratase is located in the: A. Mitochondria B. Cytosol C. Nucleus D. ER

B. Cytosol

Four porphobilinogen molecules combine to form: A. Protoporphyrin IX B. Hydroxymethylbilane C. Coproporphyrinogen III D. Heme

B. Hydroxymethylbilane

Hydroxymethylbilane is converted into: A. Uroporphyrinogen I B. Uroporphyrinogen III C. Coproporphyrinogen I D. Protoporphyrin IX

B. Uroporphyrinogen III

The physiologically relevant porphyrin isomer is: A. Type I B. Type II C. Type III D. Type IV

C. Type III

Coproporphyrinogen III is transported into the mitochondria and converted to: A. Uroporphyrin B. Protoporphyrin IX C. Porphobilinogen D. Heme

B. Protoporphyrin IX

The enzyme responsible for inserting iron into protoporphyrin IX is: A. ALA synthase B. ALA dehydratase C. Porphobilinogen deaminase D. Ferrochelatase

D. Ferrochelatase

Ferrochelatase inserts which form of iron? A. Fe³⁺ B. Fe²⁺ C. Fe⁰ D. Fe⁴⁺

B. Fe²⁺

Lead inhibits which TWO enzymes of heme synthesis? A. ALA synthase and ferrochelatase B. ALA dehydratase and ferrochelatase C. Porphobilinogen deaminase and ALA synthase D. Uroporphyrinogen decarboxylase and ferrochelatase

B. ALA dehydratase and ferrochelatase

Inhibition of ALA dehydratase causes accumulation of: A. Glycine B. Succinyl-CoA C. ALA D. Protoporphyrin IX

C. ALA

Inhibition of ferrochelatase results in accumulation of: A. Heme B. Protoporphyrin IX C. Porphobilinogen D. Coproporphyrinogen

B. Protoporphyrin IX

A biochemical hallmark of lead poisoning is: A. Increased hemoglobin synthesis B. Increased ATP production C. Basophilic stippling due to RNA aggregation D. Increased bilirubin conjugation

C. Basophilic stippling due to RNA aggregation

Lead poisoning often presents with which anemia type? A. Megaloblastic B. Hemolytic C. Microcytic hypochromic D. Macrocytic

C. Microcytic hypochromic

. Vitamin B₆ deficiency impairs heme synthesis by affecting: A. Ferrochelatase B. ALA dehydratase C. ALA synthase D. Porphobilinogen deaminase

C. ALA synthase

The anemia seen in vitamin B₆ deficiency is most commonly: A. Megaloblastic B. Microcytic hypochromic C. Normocytic normochromic D. Hemolytic

B. Microcytic hypochromic

The most heavily regulated step of heme synthesis is: A. Iron insertion B. Porphyrin ring closure C. ALA synthesis D. Coproporphyrinogen transport

C. ALA synthesis

. Increased heme concentration in cells leads to: A. Increased ALA synthase transcription B. Inhibition of ALA synthase C. Activation of ferrochelatase D. Increased porphyrin production

B. Inhibition of ALA synthase

Which tissue has the highest rate of heme synthesis? A. Kidney B. Liver and bone marrow C. Brain D. Spleen

B. Liver and bone marrow

Porphyrias are primarily caused by: A. Increased iron absorption B. Defects in heme degradation C. Enzyme deficiencies in heme biosynthesis D. Excess globin synthesis

C. Enzyme deficiencies in heme biosynthesis

Accumulation of porphyrin precursors commonly results in: A. Increased ATP production B. Photosensitivity and neurotoxicity C. Hyperglycemia D. Increased oxygen affinity

B. Photosensitivity and neurotoxicity

Acute intermittent porphyria results from deficiency of: A. ALA synthase B. ALA dehydratase C. Porphobilinogen deaminase D. Ferrochelatase

C. Porphobilinogen deaminase

Porphyrin compounds are characterized by: A. Hydrophobic tetrapeptides B. Tetrapyrrole ring structures C. Polysaccharide chains D. Lipoprotein complexes

B. Tetrapyrrole ring structures

The hallmark biochemical accumulation in AIP is: A. Protoporphyrin IX B. ALA and porphobilinogen C. Uroporphyrinogen III D. Coproporphyrinogen

B. ALA and porphobilinogen

Acute intermittent porphyria classically presents with: A. Severe photosensitivity B. Neurovisceral symptoms without photosensitivity C. Hemolysis D. Jaundice

B. Neurovisceral symptoms without photosensitivity

Drugs that induce cytochrome P450 enzymes can precipitate AIP because they: A. Increase heme degradation B. Increase ALA synthase activity C. Inhibit ferrochelatase D. Reduce porphyrin synthesis

B. Increase ALA synthase activity

PCT results from deficiency of: A. Uroporphyrinogen decarboxylase B. Ferrochelatase C. ALA synthase D. Porphobilinogen deaminase

A. Uroporphyrinogen decarboxylase

EPP is caused by deficiency of: A. Ferrochelatase B. ALA dehydratase C. Coproporphyrinogen oxidase D. Uroporphyrinogen synthase

A. Ferrochelatase

The hallmark clinical feature of PCT is: A. Neuropathy B. Hemolytic anemia C. Photosensitivity with blistering skin lesions D. Cyanosis

C. Photosensitivity with blistering skin lesions

Accumulation of which compound occurs in EPP? A. ALA B. Protoporphyrin IX C. Coproporphyrin D. Uroporphyrin

B. Protoporphyrin IX

CEP results from deficiency of: A. Uroporphyrinogen III synthase B. ALA synthase C. Ferrochelatase D. Coproporphyrinogen oxidase

A. Uroporphyrinogen III synthase

CEP is characterized by: A. Mild anemia only B. Severe photosensitivity and red-colored urine C. Cyanosis D. Metabolic acidosis

B. Severe photosensitivity and red-colored urine

Which porphyria is MOST associated with neuropsychiatric symptoms? A. PCT B. AIP C. EPP D. CEP

B. AIP

Which porphyria is MOST associated with photosensitivity WITHOUT severe neurologic symptoms? A. AIP B. PCT C. Lead poisoning D. Sideroblastic anemia

B. PCT

Hemoglobin consists of: A. Four heme groups only B. Two globin chains C. Four globin chains and four heme groups D. Two heme groups and four globin chains

C. Four globin chains and four heme groups

Adult hemoglobin A (HbA) contains: A. α₂β₂ B. α₂γ₂ C. α₂δ₂ D. β₄

A. α₂β₂

Fetal hemoglobin contains: A. α₂β₂ B. α₂γ₂ C. γ₄ D. α₂δ₂

B. α₂γ₂

β-thalassemia results from: A. Reduced β-globin synthesis B. Increased β-globin synthesis C. Defective heme formation D. Increased iron absorption only

A. Reduced β-globin synthesis

HbF has higher oxygen affinity because it: A. Binds 2,3-BPG strongly B. Does not bind 2,3-BPG efficiently C. Lacks heme D. Has increased iron content

B. Does not bind 2,3-BPG efficiently

Hemoglobin switching refers to: A. Oxygen binding changes B. Transition from fetal to adult globin synthesis C. Heme degradation D. RBC membrane remodeling

B. Transition from fetal to adult globin synthesis

A rightward shift of the O₂ curve occurs with: A. Decreased CO₂ B. Increased pH C. Increased temperature D. Decreased 2,3-BPG

C. Increased temperature

α-thalassemia results from: A. β-globin mutations B. Deletion of α-globin genes C. Ferrochelatase deficiency D. Increased porphyrin production

B. Deletion of α-globin genes

Sickle cell anemia results from mutation causing: A. Replacement of glutamic acid with valine B. Replacement of valine with glutamic acid C. Replacement of lysine with glycine D. Iron substitution

A. Replacement of glutamic acid with valine

Polymerization of HbS occurs primarily during: A. Oxygenated state B. Deoxygenated state C. High pH D. Low temperature

B. Deoxygenated state

Cooperative oxygen binding means: A. Each heme binds oxygen independently B. Oxygen binding increases affinity at remaining sites C. Oxygen binding reduces Hb stability D. Only one oxygen binds Hb

B. Oxygen binding increases affinity at remaining sites

The Bohr effect describes: A. Oxygen displacement by CO B. Effect of pH and CO₂ on oxygen binding C. Heme synthesis D. Methemoglobin formation

B. Effect of pH and CO₂ on oxygen binding

Carbon monoxide poisoning decreases oxygen delivery because CO: A. Competes with oxygen and increases Hb affinity for O₂ B. Destroys heme C. Reduces iron D. Inhibits glycolysis

A. Competes with oxygen and increases Hb affinity for O₂

Myoglobin differs from hemoglobin because it: A. Has four subunits B. Displays cooperative binding C. Has higher oxygen affinity and is monomeric D. Binds 2,3-BPG

C. Has higher oxygen affinity and is monomeric

Heme degradation produces: A. Bilirubin, iron, and carbon monoxide B. Biliverdin only C. Iron and lactate D. Bilirubin and ATP

A. Bilirubin, iron, and carbon monoxide

RBC destruction occurs primarily in the: A. Liver and spleen B. Kidney C. Bone marrow D. Lung

A. Liver and spleen

The enzyme converting heme to biliverdin is: A. Heme oxygenase B. Biliverdin reductase C. ALA synthase D. Ferrochelatase

A. Heme oxygenase

Biliverdin is converted to bilirubin by: A. Biliverdin reductase B. Glucuronyl transferase C. Heme oxygenase D. Lactate dehydrogenase

A. Biliverdin reductase

Unconjugated bilirubin is transported in blood bound to: A. Transferrin B. Albumin C. Globulin D. Hemoglobin

B. Albumin

Conjugation of bilirubin occurs in the: A. Kidney B. Spleen C. Liver D. Intestine

C. Liver

Conjugated bilirubin is excreted into: A. Urine directly B. Bile C. Plasma D. Bone marrow

B. Bile

Urobilinogen is formed in the: A. Liver B. Intestine C. Kidney D. Spleen

B. Intestine

Jaundice due to impaired bilirubin conjugation is called: A. Prehepatic jaundice B. Hepatic jaundice C. Posthepatic jaundice D. Hemolytic jaundice

B. Hepatic jaundice

Stercobilin gives stool its: A. Yellow color B. Brown color C. Green color D. Black color

B. Brown color

RBC Flashcards

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