Biochem 42 Flashcards

A skin biopsy 6 hours after bacterial cellulitis shows the earliest leukocyte influx expected in acute inflammation. Which cell type should predominate first?

A) Basophils

B) Monocytes

C) Eosinophils

D) Neutrophils

A child with helminth infection and asthma has increased leukocytes with large red cytoplasmic granules. Which association best matches this cell?

A) Viral killing; lymph nodes

B) Allergy; parasites; chronic inflammation

C) Acute bacteria; pus formation

D) Antibody production; plasma cells

Which statement best matches eosinophils with their classic microscopic and tissue features?

A) Red granules

B) Blue granules

C) No granules

D) Tertiary granules

A healthy adult female has blood centrifuged for hematocrit measurement. Which packed red-cell volume is expected?

A) 20–30%

B) 25–35%

C) 35–45%

D) 50–60%

Which hemoglobin-chain pairing correctly describes adult hemoglobin A?

A) Two alpha; two beta

B) Two alpha; two gamma

C) Two alpha; two delta

D) Two beta; two delta

Which hemoglobin-chain pairing correctly describes adult hemoglobin A2?

A) Two beta; two gamma

B) Two alpha; two delta

C) Two alpha; two beta

D) Two gamma; two delta

Which hemoglobin-chain pairing correctly describes fetal hemoglobin?

A) Two alpha; two beta

B) Two beta; two delta

C) Two alpha; two delta

D) Two alpha; two gamma

A patient with sickle cell disease has abnormal polymerizing hemoglobin. Which mutation best explains the disease?

A) Alpha-chain deletion

B) Gamma-chain persistence

C) Beta-globin point mutation

D) Delta-chain duplication

In sickle cell anemia, which amino-acid substitution occurs in the abnormal beta-globin chain?

A) Valine to glutamic acid

B) Glutamic acid to valine

C) Lysine to arginine

D) Glycine to proline

Which hemoglobin mutation name is classically present in sickle cell anemia?

A) HbC

B) HbA2

C) HbF

D) HbS

During hematopoiesis, which progenitor gives rise to erythroid colony-forming units?

A) Multipotential myeloid stem cell

B) Mature erythrocyte

C) Circulating reticulocyte

D) Megakaryocyte lineage

Which erythropoiesis transition occurs earliest in normal red-cell maturation?

A) Reticulocyte to erythrocyte

B) Normoblast to reticulocyte

C) Proerythroblast to basophilic erythroblast

D) Band cell to neutrophil

Which late erythropoiesis sequence is correctly ordered?

A) Reticulocyte before erythrocyte

B) Erythrocyte before normoblast

C) Myelocyte before reticulocyte

D) Band before erythrocyte

A patient living at high altitude develops increased red-cell production. Which organ-hormone pairing drives this response?

A) Liver; thrombopoietin

B) Spleen; histamine

C) Marrow; PDGF

D) Kidney; erythropoietin

A patient with chronic blood loss develops small pale red cells. Which deficiency best matches this microcytic anemia?

A) Folate deficiency

B) Iron deficiency

C) Vitamin B12 deficiency

D) EPO deficiency

A patient with impaired DNA synthesis develops enlarged red-cell precursors. Which deficiency best matches macrocytic anemia?

A) Folate deficiency

B) Iron deficiency

C) Histamine deficiency

D) PDGF deficiency

Which classification correctly divides white blood cells into two major groups?

A) Platelets and erythrocytes

B) Myeloid and erythroid cells

C) Granulocytes and agranulocytes

D) Plasma cells and stem cells

Which set contains only granulocytes?

A) Monocytes; lymphocytes; NK cells

B) Basophils; eosinophils; neutrophils

C) Platelets; monocytes; neutrophils

D) B cells; T cells; basophils

Among granulocytes, which cell type is classically described as having tertiary granules?

A) Neutrophils

B) Basophils

C) Eosinophils

D) Monocytes

After leaving marrow, neutrophils can occupy which two peripheral compartments?

A) Formation; storage

B) Circulating; marginating

C) Erythroid; megakaryocytic

D) B-cell; T-cell

A neutrophil tethers to vascular endothelium during inflammation. Which adhesion molecule is involved in this binding?

A) E-selectin

B) P-selectin

C) Integrin beta-chain

D) L-selectin

Which cell is the first recognizable precursor in granulocyte development?

A) Myeloblast

B) Promyelocyte

C) Metamyelocyte

D) Band cell

Which granulocyte maturation sequence is correctly ordered after the myeloblast stage?

A) Myelocyte; promyelocyte; band; metamyelocyte

B) Promyelocyte; myelocyte; metamyelocyte; band

C) Band; metamyelocyte; myelocyte; promyelocyte

D) Metamyelocyte; band; promyelocyte; myelocyte

Which two leukocyte classes are agranulocytes?

A) Neutrophils and basophils

B) Eosinophils and monocytes

C) Lymphocytes and monocytes

D) Platelets and lymphocytes

The bipotential CFU-GM progenitor can differentiate into which two lineages?

A) Platelets or erythrocytes

B) Monocytes or neutrophils

C) B cells or T cells

D) Eosinophils or basophils

Which marrow-derived platelet precursor normally remains in bone marrow rather than circulating intact?

A) Megakaryocyte

B) Reticulocyte

C) Myeloblast

D) Normoblast

Which list correctly names the four platelet granule types?

A) Primary; secondary; tertiary; azurophilic

B) Alpha; beta; gamma; delta

C) Dense; clear; red; blue

D) Alpha; delta; gamma; lambda

Which major lymphocyte types should be grouped together?

A) B cells; T cells; NK cells

B) Monocytes; neutrophils; NK cells

C) Basophils; eosinophils; B cells

D) Platelets; T cells; monocytes

A patient undergoes splenic immune activation after a bloodstream infection. Which set best summarizes normal spleen functions?

A) Store bile; activate neutrophils

B) Make EPO; filter lymph

C) Activate lymphocytes; filter blood antigens

D) Produce platelets; degrade heme

A patient with chronic hypoxemia develops increased erythropoiesis. Which kidney-derived hormone mediates this response?

A) Erythropoietin

B) Thrombopoietin

C) Angiotensin II

D) Aldosterone

In mature erythrocytes, which metabolic route is dominant and feeds the pathway producing 2,3-BPG?

A) TCA cycle; malate shunt

B) Beta-oxidation; carnitine shuttle

C) Pentose pathway; NADPH route

D) Glycolysis; Rapoport-Leubering shunt

The hexose monophosphate shunt protects RBCs from oxidative damage by generating which paired products?

A) ATP; oxidized glutathione

B) NADPH; reduced glutathione

C) FADH2; reduced hemoglobin

D) NADH; ferric iron

What is involved in the first and what is involved in the rate-limiting step in heme biosynthesis:

A) Acetyl-CoA and alanine

B) Citrate and serine

C) Succinyl-CoA and glycine

D) Pyruvate and glutamate

A blood smear shows malformed spherical RBCs, while another sample shows immature circulating RBCs. Which pairing is correct?

A) Spherocytes; reticulocytes

B) Schistocytes; normoblasts

C) Reticulocytes; spherocytes

D) Megakaryocytes; platelets

A marrow biopsy shows large multinucleated cells releasing cytoplasmic fragments into sinusoids. Which blood element is produced this way?

A) Eosinophils

B) Monocytes

C) Reticulocytes

D) Platelets

A patient has microcytic, hypochromic anemia due impaired hemoglobin synthesis. Which cause set best fits?

A) B12; folate; erythroleukemia

B) Iron def; thalassemia; lead poisoning

C) Bleeding; sickle disease; PK defect

D) Splenectomy; malaria; methemoglobinemia

A patient develops macrocytic, normochromic anemia from impaired DNA synthesis. Which cause set best fits?

A) Iron deficiency; lead poisoning

B) Acute bleeding; sickle disease

C) B12 deficiency; folate deficiency

D) G6PD deficiency; malaria resistance

A patient has normocytic, normochromic anemia from red-cell loss or destruction. Which cause set best fits?

A) Bleeding; sickle disease; metabolic defects

B) Iron deficiency; thalassemia; lead poisoning

C) B12 deficiency; folate deficiency

D) DMT1 mutation; pyridoxine deficiency

A patient at high altitude has increased erythrocyte 2,3-BPG. What is the main physiologic effect?

A) Increased hemoglobin oxygen affinity

B) Blocked oxygen release to tissues

C) Methemoglobin reduction in RBCs

D) Enhanced oxygen unloading to tissues

An inherited RBC enzyme deficiency causes hemolytic anemia, with compensatory increased 2,3-BPG improving tissue oxygen delivery. Which enzyme is deficient?

A) Cytochrome b5 reductase

B) Glucose-6-phosphatase

C) Pyruvate kinase

D) Ferrochelatase

Congenital methemoglobinemia can result from hemoglobin M or deficiency of which enzyme?

A) Cytochrome b5 reductase

B) Glucose-6-P dehydrogenase

C) Gamma-ALA synthase

D) Pyruvate kinase

Which inherited RBC enzyme deficiency is common in humans partly because it protects against malaria?

A) Pyruvate kinase deficiency

B) G6PD deficiency

C) Cytochrome b5 reductase deficiency

D) DMT1 deficiency

A patient with G6PD-deficient red cells is being evaluated for RBC survival. Which change is expected?

A) Longer RBC lifespan

B) Normal RBC half-life

C) Increased platelet survival

D) Reduced RBC half-life

A malnourished patient develops microcytic, hypochromic anemia because the first heme-synthesis reaction slows. Which deficiency best explains this?

A) Vitamin B12 deficiency

B) Folate deficiency

C) Pyridoxine deficiency

D) Vitamin C deficiency

A child with abdominal pain and microcytic anemia has accumulation of gamma-ALA and protoporphyrin IX. Which exposure best explains this?

A) Lead

B) Iron

C) Phenobarbital

D) Malaria

Dietary iron is absorbed as Fe2+ but must become Fe3+ for transport. Which protein performs this oxidation?

A) Ferritin

B) Hemosiderin

C) Transferrin

D) Ceruloplasmin

Which iron-handling pairing is correct for blood transport, usual storage, and excess storage?

A) Ferritin; transferrin; DMT1

B) Transferrin; ferritin; hemosiderin

C) Hemosiderin; ferritin; transferrin

D) Ceruloplasmin; DMT1; transferrin

A patient has photosensitivity, facial hypertrichosis, and scarring due an inherited heme-synthesis enzyme defect. Which disorder group fits best?

A) Porphyrias

B) Thalassemias

C) Sideroblastic anemias

D) Methemoglobinemias

Which variable best correlates with the lifetime of an erythrocyte?

A) Plasma transferrin saturation

B) Splenic platelet storage

C) Glucose-6-P activity

D) Serum ceruloplasmin activity

A patient has microcytic, hypochromic anemia due an inherited SLC11A2 mutation. Which encoded protein is affected?

A) Ferroportin

B) DMT-1

C) Transferrin

D) Ceruloplasmin

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A physician evaluating iron deficiency anemia in an adult man worries about occult GI blood loss. Which etiologies best match this concern?

A) Ulcers or colon cancer

B) Asthma or eczema

C) Hemophilia or leukemia

D) Malaria or porphyria

Phenobarbital induces cytochrome P450 enzymes that use heme. Which compensatory response increases heme synthesis?

A) Reduced DMT1 expression

B) Induced gamma-ALA synthase

C) Blocked bilirubin conjugation

D) Increased cytochrome b5 reductase

During normal heme catabolism, which product is conjugated with glucuronic acid and excreted in bile?

A) Protoporphyrin IX

B) Gamma-ALA

C) Bilirubin

D) Hemosiderin

An RBC membrane disorder affects the major erythrocyte cytoskeletal protein. Which protein is most likely defective?

A) Ferritin

B) Transferrin

C) Ceruloplasmin

D) Spectrin

A patient has hemolytic anemia from unstable erythrocyte membranes. Which defect category best explains this?

A) Cytoskeletal protein defects

B) Platelet granule defects

C) EPO receptor deactivation

D) Transferrin transport defects

A bone marrow transplant sample is enriched before infusion to improve engraftment. Which cell population should be increased?

A) Reticulocytes

B) Stem cells

C) Mature erythrocytes

D) Megakaryocytes

A family has excessive RBC production from an EPO receptor mutation causing sustained JAK2-STAT5 signaling. Which negative regulator cannot deactivate the receptor?

A) DMT-1

B) Spectrin

C) SHP-1

D) Ceruloplasmin

Which mechanism best explains megaloblastic anemia from folate or B12 deficiency?

A) Early nuclear extrusion after fewer divisions

B) Excess hemoglobin concentration per cell

C) Increased splenic platelet sequestration

D) Ferric hemoglobin accumulation

HbC differs from normal beta-globin by which substitution at the same position affected in HbS?

A) Glu-to-Val

B) Lys-to-Glu

C) Val-to-Glu

D) Glu-to-Lys

Why are HbS/HbC patients usually more symptomatic than HbA/HbS patients?

A) Less HbS polymerizes in RBCs

B) Higher HbS concentration enhances sickling

C) HbC prevents oxygen unloading

D) HbA increases RBC dehydration

Which disorder group results from imbalanced alpha- and beta-globin chain synthesis?

A) Porphyrias

B) Methemoglobinemias

C) Thalassemias

D) Spherocytoses

Absence of all four alpha-globin genes is classically associated with which condition?

A) Hydrops fetalis

B) HbC disease

C) Beta-thalassemia minor

D) Congenital methemoglobinemia

In beta-thalassemia, which genotype is expected to cause severe disease?

A) β+/β+

B) βA/βS

C) β+/βA

D) β0/β0

Compared with HbA, HbF binds 2,3-BPG differently in a way that causes which effect?

A) Lower 2,3-BPG affinity; higher oxygen affinity

B) Higher 2,3-BPG affinity; lower oxygen affinity

C) Lower 2,3-BPG affinity; lower oxygen affinity

D) Higher 2,3-BPG affinity; higher oxygen affinity

Patients with beta-thalassemia or sickle cell anemia often have milder disease when which hemoglobin is elevated?

A) HbA

B) HbA2

C) HbF

D) HbC

Mutations in spectrin, ankyrin, or band 3 most directly cause which RBC abnormality?

A) Methemoglobin formation

B) Spherocyte formation

C) HbF persistence

D) Porphyrin accumulation

Which pairing correctly describes the alpha-globin locus?

A) Chromosome 11; epsilon gene

B) Chromosome 11; gamma genes

C) Chromosome 16; zeta and alpha genes

D) Chromosome 16; beta and delta genes

Which pairing correctly describes the beta-globin locus?

A) Chromosome 11; epsilon and fetal genes

B) Chromosome 16; zeta and alpha genes

C) Chromosome 11; only beta genes

D) Chromosome 16; gamma and beta genes

Normal functional hemoglobin within RBCs contains iron in which form?

A) Ferric

B) Ferrous

C) Hemosiderin-bound

D) Transferrin-bound

Ferric hemoglobin within RBCs is best described by which term?

A) Oxyhemoglobin

B) Carboxyhemoglobin

C) Deoxyhemoglobin

D) Methemoglobin

Inherited defects in heme-synthesis enzymes produce which disease group?

A) Thalassemias

B) Porphyrias

C) Spherocytoses

D) Hemoglobinopathies

Unlike mature RBCs, white blood cells normally have which structural feature?

A) Nuclei

B) Hemoglobin

C) Spectrin

D) Reticulin

Which granulocyte rapidly migrates to infection or tissue damage?

A) Basophil

B) Eosinophil

C) Monocyte

D) Neutrophil

Which cell type is especially important against parasites and removes fibrin during inflammation?

A) Eosinophil

B) Basophil

C) Neutrophil

D) Lymphocyte

A patient with asthma and allergic disease has increased granulocytes. Which cell is most expected?

A) Neutrophils

B) Eosinophils

C) Monocytes

D) NK cells

Increased eosinophils are associated with which condition set?

A) Asthma; allergies; autoimmune disease

B) Bleeding; hemolysis; iron deficiency

C) Thymic maturation; viral killing

D) Platelet budding; clot retraction

Which granulocyte participates in hypersensitivity reactions and stores histamine?

A) Neutrophil

B) Eosinophil

C) Basophil

D) Monocyte

A lymphocyte precursor must mature into a T cell. Which organ is required?

A) Thymus

B) Spleen

C) Bone marrow

D) Lymph node

Which site is responsible for B-cell maturation?

A) Thymus

B) Bone marrow

C) Spleen

D) Liver

Tissue macrophages arise from which circulating precursor cell?

A) Neutrophils

B) Basophils

C) Monocytes

D) Reticulocytes

An RBC enzyme defect blocks phosphoenolpyruvate conversion to pyruvate. Which metabolite is expected to rise?

A) Heme

B) 2,3-BPG

C) Methemoglobin

D) Reduced glutathione

Erythrocyte glycolysis generates 2,3-BPG through which pathway?

A) Hexose monophosphate shunt

B) Urea cycle

C) Rapoport-Luebering shunt

D) Carnitine shuttle

How does 2,3-BPG promote oxygen delivery to tissues?

A) Stabilizes deoxyhemoglobin

B) Stabilizes ferric hemoglobin

C) Oxidizes ferrous iron

D) Activates cytochrome b5

Congenital methemoglobinemia is classically caused by deficiency of which enzyme?

A) Ferrochelatase

B) G6PD

C) δ-ALA synthase

D) Cytochrome b5 reductase

Inherited hemoglobin M causes methemoglobinemia by stabilizing iron in which state?

A) Fe0

B) Fe2+

C) Fe3+

D) Fe4+

For hemoglobin to bind oxygen normally, iron must be in which form?

A) Ferric; Fe3+

B) Ferrous; Fe2+

C) Heme-free; Fe0

D) Oxidized; Fe4+

Cytochrome b5 is regenerated in RBCs using which reducing agent?

A) NADH

B) NADPH

C) FADH2

D) ATP

Which RBC pathway generates NADPH for antioxidant protection?

A) Rapoport-Luebering shunt

B) TCA cycle

C) Hexose monophosphate shunt

D) Beta-oxidation

The chief RBC defense against ROS injury to proteins and lipids is which molecule?

A) Ferritin

B) Reduced glutathione

C) Transferrin

D) Methemoglobin

Which molecule maintains glutathione in its reduced protective state?

A) NADPH

B) NADH

C) 2,3-BPG

D) δ-ALA

Which enzyme catalyzes the first step of the hexose monophosphate shunt?

A) δ-ALA dehydratase

B) G6PD

C) Ferrochelatase

D) Porphobilinogen deaminase

Which porphyrin type is most common in nature?

A) Type I

B) Type II

C) Type III

D) Type IV

Which porphyrin is the most common in the human body?

A) Bilirubin

B) Heme

C) Porphobilinogen

D) Protoporphyrinogen

Known G6PD variant genes most often contain which mutation types?

A) Nonsense; frameshift deletions

B) Missense; in-frame deletions

C) Duplications; promoter insertions

D) Translocations; trinucleotide repeats

Heme synthesis begins with which two starter substrates?

A) Glycine; succinyl CoA

B) Alanine; acetyl CoA

C) Serine; pyruvate

D) Glutamate; citrate

The first intermediate formed from glycine and succinyl CoA in heme synthesis is what?

A) Protoporphyrin IX

B) Porphobilinogen

C) δ-Aminolevulinic acid

D) Uroporphyrinogen III

Producing one heme molecule requires how many glycines and succinyl CoA molecules?

A) Two of each

B) Four of each

C) Six of each

D) Eight of each

Heme regulates its own synthesis by repressing which enzyme?

A) δ-ALA synthase

B) Ferrochelatase

C) Uroporphyrinogen decarboxylase

D) Coproporphyrinogen oxidase

δ-ALA dehydratase converts δ-ALA into which pyrrole product?

A) Porphobilinogen

B) Heme

C) Biliverdin

D) Protoporphyrin IX

Lead poisoning directly inhibits which two heme-synthesis enzymes?

A) G6PD and ferrochelatase

B) δ-ALA dehydratase and ferrochelatase

C) Porphobilinogen deaminase and G6PD

D) Cytochrome b5 and DMT-1

A child with lead toxicity develops impaired heme synthesis. Which metabolites accumulate?

A) δ-ALA and protoporphyrin IX

B) Heme and bilirubin

C) Glycine and succinyl CoA

D) Ferritin and transferrin

Which nutrient increases absorption of nonheme iron from the digestive tract?

A) Vitamin B12

B) Folate

C) Vitamin C

D) Vitamin K

Which pairing correctly describes iron absorption and transport states?

A) Absorbed Fe3+; transported Fe2+

B) Absorbed Fe2+; transported Fe3+

C) Absorbed Fe0; transported Fe2+

D) Absorbed Fe3+; transported Fe0

A patient with excess porphyrin production develops skin symptoms after sunlight exposure. Which symptom best fits?

A) Photosensitivity

B) Hemarthrosis

C) Night blindness

D) Splenomegaly

Iron is carried in blood when apotransferrin binds iron to form which complex?

A) Ferritin

B) Transferrin

C) Hemosiderin

D) Ceruloplasmin

Ferrous iron leaves the endosome and enters cytoplasm through which transporter?

A) Band 3

B) Ferrochelatase

C) DMT-1

D) Ankyrin

An SLC11A2 mutation disrupts DMT-1 function. Which anemia pattern is expected?

A) Macrocytic normochromic anemia

B) Iron-deficiency anemia

C) Aplastic anemia

D) Megaloblastic anemia

How does heme regulate hemoglobin synthesis?

A) Stimulates globin synthesis

B) Blocks transferrin binding

C) Degrades spectrin

D) Inhibits bilirubin conjugation

Normal heme degradation ultimately forms which pigment?

A) Stercobilin

B) Ferritin

C) Bilirubin

D) Protoporphyrin IX

The first step of heme degradation releases which gaseous product?

A) CO

B) NO

C) O2

D) CO2

In the liver, bilirubin reacts with UDP-glucuronate to form which water-soluble product?

A) Urobilinogen

B) Bilirubin monoglucuronide

C) Stercobilin

D) Protoporphyrin IX

Intestinal bacteria deconjugate bilirubin diglucuronide into which compound?

A) Urobilinogen

B) UDP-glucuronate

C) Biliverdin

D) Hemosiderin

Most intestinal urobilinogen is converted into which fecal pigment?

A) Bilirubin

B) Heme

C) Stercobilin

D) Ferritin

Which organ determines whether circulating RBCs remain viable?

A) Liver

B) Kidney

C) Thymus

D) Spleen

Which pairing correctly links spectrin to the RBC membrane bilayer?

A) Ankyrin; assisted by band 3

B) DMT-1; assisted by ferritin

C) Transferrin; assisted by ceruloplasmin

D) Actin; assisted by HbF

Which RBC cytoskeletal protein helps stabilize ankyrin-band 3 membrane attachment?

A) Band 4.2

B) Glycophorin C

C) Ferrochelatase

D) Globin

Band 4.1 anchors spectrin by binding which two proteins?

A) Ankyrin and band 3

B) Glycophorin C and actin

C) Ferritin and transferrin

D) DMT-1 and ceruloplasmin

Leukemias are best described as which hematopoietic abnormality?

A) Excess platelet granule release

B) Complete erythrocyte maturation

C) Incomplete hematopoietic cell development

D) Accelerated bilirubin conjugation

In sickle-cell anemia, which beta-globin substitution produces HbS?

A) E6K

B) G6V

C) E6V

D) V6E

HbC is caused by which beta-globin substitution?

A) E6V

B) E6K

C) K6E

D) V6K

Which feature is characteristic of HbC protein within RBCs?

A) Hemoglobin precipitation

B) Ferric iron stabilization

C) Increased HbF switching

D) Decreased globin synthesis

An imbalance with excess production of one hemoglobin subunit over another causes which disease class?

A) Porphyrias

B) Methemoglobinemias

C) Thalassemias

D) Leukemias

Alpha-thalassemias usually arise from which genetic defect?

A) β-promoter point mutations

B) Complete α-globin gene deletions

C) δ and β deletions

D) Missense ferrochelatase mutations

Which thalassemia type is generally more severe?

A) α-thalassemia

B) β-thalassemia

C) δ-thalassemia

D) γ-thalassemia

Which β-thalassemia genotype ranking is most severe to least severe?

A) β+/β+ > β+/β0 > β0/β0

B) β0/β0 > β+/β0 > β+/β+

C) β+/β0 > β0/β0 > β+/β+

D) β+/β+ > β0/β0 > β+/β0

Excess β-chains in thalassemia can form which homotetramer

A) HbS

B) HbC

C) HbF

D) HbH

Excess α-chain production damages which RBC cytoskeletal protein?

A) Band 4.1

B) Ankyrin

C) DMT-1

D) Ceruloplasmin