Hematology MCQs with Answer and Explanations | Chapter 6

Answer: Dilutional thrombocytopenia

Massive transfusion dilutes a patient’s platelets, which are essential for blood clotting. This dilution can lead to dilutional thrombocytopenia, a condition where the platelet count falls below the normal range, increasing the risk of bleeding (hemorrhage).

The other options are incorrect:

• Increased t-PA: Tissue plasminogen activator (t-PA) actually breaks down clots, so an increase wouldn’t cause hemorrhage.
• Vitamin K deficiency: Vitamin K deficiency primarily affects the production of clotting factors, not platelets. While it can increase bleeding risk, it’s not the main concern here.
• Decreased Fibrinogen: While decreased fibrinogen, a protein involved in clot formation, can contribute to bleeding, massive transfusion primarily affects platelet levels.

Answer: All of the above

Heparin, although used as an anticoagulant to prevent blood clotting in the sample, can cause certain artifacts in arterial blood gas (ABG) analysis. Here’s how:

• pCO2 (partial pressure of carbon dioxide): Heparin can dissolve some CO2 gas from the blood, leading to an underestimation of the true pCO2 value.
• HCO3 (bicarbonate): Since pCO2 and bicarbonate (HCO3) are interrelated in maintaining blood pH, a decrease in pCO2 due to heparin can lead to a calculated decrease in HCO3.
• pH: In most cases, the buffering capacity of blood helps to maintain pH despite changes in pCO2. However, in some situations with severe metabolic acidosis, heparin-induced pCO2 changes might slightly affect the calculated pH.

Answer: Chemical which prevent bleeding

Anticoagulants are medications that interfere with the blood clotting process. They don’t directly stop bleeding, but rather prevent the formation of clots that can block blood vessels and lead to serious complications like strokes or heart attacks.

The other options are incorrect:

• Liquids which stop bleeding: Anticoagulants are not simply liquids that stop existing bleeding. They work by affecting the clotting cascade, a complex series of steps involved in clot formation.
• Salt That allows Blood to clot: Salts like calcium are actually necessary for blood clotting. Anticoagulants work in opposition to these clotting factors.
• All of the above: Anticoagulants prevent, not stop, bleeding and are not salts that allow clotting.

Answer: 6 Hours

Platelet-Rich Plasma (PRP) maintains its quality and effectiveness for up to 6 hours after whole blood collection. Beyond this timeframe, platelet function and viability start to decline, reducing its potential benefits in treatment.

The other options are incorrect:

• 24 Hours: While PRP can be stored for up to 24 hours in some cases with special additives, 6 hours is generally considered the optimal timeframe for maintaining its best quality.
• 8 Hours: Similar to 24 hours, 8 hours might be possible with specific storage methods, but 6 hours is the recommended window for optimal PRP function.
• Any time but should be refrigerated: Refrigeration can slow down platelet degradation, but it’s not enough to ensure optimal PRP function for an extended period. Using PRP within 6 hours is crucial for maximum effectiveness.

Answer: PPP

Centrifuging whole blood at low speed separates its components based on their density. Red blood cells (RBCs) being the heaviest, will sediment at the bottom. Platelets and white blood cells (WBCs) form a thin buffy coat in the middle. Finally, the top layer will be a straw-colored liquid called platelet-poor plasma (PPP). This PPP contains most of the plasma proteins, clotting factors, and other components except for most cells and platelets.

The other options are incorrect:

• RPR (Rapid Plasma Reagin): RPR is a blood test for syphilis, not a component separated by centrifuging whole blood.
• PC (Packed Cells): Packed cells refer to concentrated red blood cells after removing most of the plasma, achieved through centrifugation at higher speeds.
• WBC (White Blood Cells): While WBCs are present in whole blood, low-speed centrifugation concentrates them in the buffy coat, not the top layer (PPP).

Answer: 1%

A 1 unit rise in hemoglobin (Hb) concentration typically corresponds to a 1% increase in hematocrit in a unit of packed red blood cells (PRBCs) or whole blood.

The other options are incorrect:

• 0.1%: This option represents a smaller increase in Hb concentration compared to what is typically observed with the transfusion of 1 unit of blood. A 0.1% rise in Hb would be too small to be clinically significant in most cases.
• 10%: A 10% increase in Hb concentration would be a substantial rise and is not consistent with the typical increase seen with the transfusion of 1 unit of blood.
• 5%: Similar to the 10% option, a 5% increase in Hb concentration would be higher than what is typically observed with the transfusion of 1 unit of blood.

Answer: All of above

Apheresis offers several advantages compared to whole blood donation:

• Avoids Circulatory Overload: Apheresis allows for the collection of specific blood components like platelets or plasma, sparing red blood cells. This reduces the risk of circulatory overload in recipients, especially those with pre-existing heart or lung conditions.
• Avoids Iron Overload: Since red blood cells contain iron, frequent whole blood donations can lead to iron overload in some recipients, particularly those with conditions like thalassemia. Apheresis allows targeted collection of needed components without excess red blood cells.
• Provides Different Blood Components to Different Patients: Apheresis allows for the separation and collection of specific blood components like platelets or plasma which can then be directed to patients with specific needs.pen_spark

Answer: Factor VIII

Cryoprecipitate is a blood product rich in clotting factors, particularly those involved in the later stages of the clotting cascade. Factor VIII, a vital protein for normal blood clot formation, is a major component of cryoprecipitate.

The other options are incorrect:

• Factor XI: While Factor XI is involved in earlier stages of clotting, it’s not a major component of cryoprecipitate.
• Factor V: Similar to Factor XI, Factor V plays a role in earlier clotting stages and isn’t as concentrated in cryoprecipitate.
• Factor X: Factor X is another clotting factor present in blood, but its concentration isn’t as high in cryoprecipitate compared to Factor VIII.

Answer: RBCs

The D antigen is a protein marker on the surface of red blood cells (RBCs) that determines an individual’s Rh blood type. People with the D antigen are Rh positive, while those lacking it are Rh negative.

The other options are incorrect:

• Platelets: Platelets are cell fragments involved in blood clotting and don’t carry the D antigen.
• WBCs (White Blood Cells): White blood cells are part of the immune system and don’t have the D antigen on their surface.
• None of these: While the D antigen isn’t present on platelets or WBCs, it is indeed found on red blood cells.

Answer: Erythropoietin

Chronic renal insufficiency (CRI) can lead to decreased production of erythropoietin (EPO) by the kidneys. EPO is a hormone that stimulates the bone marrow to produce red blood cells. A 5-year-old boy with CRI is likely to experience a deficiency in red blood cell production (anemia) due to low EPO levels. Supplementation with erythropoietin can help address this issue.

The other options are incorrect:

• G-CSF (Granulocyte-colony stimulating factor): G-CSF stimulates the production of white blood cells, not red blood cells. While a 5-year-old with CRI might be more susceptible to infections, G-CSF wouldn’t be the primary treatment for red blood cell production problems.
• Interleukin-11 (IL-11): While IL-11 has some effects on blood cell production, it’s not typically used in treating anemia associated with CRI. Erythropoietin is the more established and targeted treatment.
• Stem cell factor: Stem cell factor plays a role in the development of various blood cells, but it’s not the primary choice for treating anemia in CRI. Erythropoietin directly targets red blood cell production.

Answer: Either Vitamin B12 or folic acid deficiency

Megaloblastic anemia can occur due to deficiencies in either vitamin B12 or folic acid. Both of these vitamins are essential for DNA synthesis and red blood cell production. Deficiencies in either can result in impaired DNA synthesis, leading to the characteristic large, immature red blood cells seen in megaloblastic anemia.

The other options are incorrect:

• Vitamin B12 but not folic acid deficiency: While a B12 deficiency can cause megaloblastic anemia, a folic acid deficiency can as well.
• Folic acid but not Vitamin B12 deficiency: Similar to B12 deficiency, a folic acid deficiency can also lead to megaloblastic anemia.
• Only combined Vitamin B12 + folic acid deficiency: Megaloblastic anemia can occur due to a deficiency in either vitamin individually, not just a combined deficiency.

Answer: Cryofibrinogen

Cryofibrinogen is a cold-insoluble protein that can precipitate in the blood sample when it is cooled, leading to clumping of red blood cells and causing a spurious decrease in mean corpuscular volume (MCV) measurement.

The other options are incorrect:

• Hyperglycemia: Hyperglycemia, or high blood sugar levels, does not directly cause a spurious decrease in MCV. It may affect various blood parameters, but it typically does not interfere with the measurement of MCV.
• Autoagglutination: Autoagglutination occurs when red blood cells clump together, usually due to the presence of autoantibodies. While autoagglutination can cause inaccuracies in blood cell counts, it is more likely to lead to falsely elevated MCV rather than a decrease.
• High WBC count: A high white blood cell (WBC) count does not typically cause a spurious decrease in MCV. In fact, conditions associated with a high WBC count, such as infection or inflammation, are more likely to affect other blood parameters rather than MCV.

Answer: Pancytopenia

Pancytopenia refers to a condition where there is a reduction in the number of all three major blood cell types: red blood cells (anemia), white blood cells (leukopenia), and platelets (thrombocytopenia). It can occur due to various reasons such as bone marrow failure, certain medications, infections, autoimmune disorders, or malignancies.

The other options are incorrect:

• Erythroplasia: Erythroplasia refers to a specific skin condition, not a blood cell disorder.
• Thrombocytopenia: This term refers only to a decrease in platelets, not all blood cell lines.
• Leukopenia: Similar to thrombocytopenia, leukopenia refers specifically to a decrease in white blood cells.

Answer: 4.6-6.0

The normal range for total red blood cell (RBC) count in men is typically between 4.6 and 6.0 million cells per microliter (mcL) of blood. This range may vary slightly depending on the laboratory and the specific reference values used.

The other options are incorrect:

• 4.0-5.0 million cells/mcL: This range is too low for the normal total RBC count in men. A count of 4.0 million cells/mcL would be considered low, while the upper limit of 5.0 million cells/mcL is below the typical upper limit for men.
• 4.2-6.5 million cells/mcL: While the lower limit of this range is close to the correct answer, the upper limit of 6.5 million cells/mcL is higher than the typical upper limit for men.
• 4.0-6.0 million cells/mcL: This range includes the lower and upper limits seen in the correct answer, but the lower limit of 4.0 million cells/mcL is below the typical lower limit for men.

Answer: MCV

MCHC (Mean Corpuscular Hemoglobin Concentration), MCH (Mean Corpuscular Hemoglobin), and HCT (Hematocrit) all provide information related to the amount of hemoglobin or the number of red blood cells, but MCV (Mean Corpuscular Volume) is the specific test used to determine the average size of red blood cells.pen_spark

The other options are incorrect:

• MCH (Mean Corpuscular Hemoglobin): MCH indicates the amount of hemoglobin, not directly the size of the red blood cells.
• MCHC (Mean Corpuscular Hemoglobin Concentration): Similar to MCH, MCHC reflects hemoglobin concentration, not cell size.
• HCT (Hematocrit): HCT focuses on the red blood cell volume compared to total blood volume, not the size of individual red blood cells.

Answer: MCH

MCH (Mean Corpuscular Hemoglobin) directly measures the average weight of hemoglobin present within a single red blood cell. It’s reported in picograms (pg) per cell. The reference range you provided (27-33 pg) falls within the typical range for healthy adults.

The other options are incorrect:

• HCT (Hematocrit): HCT represents the percentage of red blood cells in whole blood, not the weight of hemoglobin within individual red blood cells.
• MCV (Mean Corpuscular Volume): MCV reflects the average size of red blood cells, not the hemoglobin weight per cell.
• MCHC (Mean Corpuscular Hemoglobin Concentration): MCHC indicates the concentration of hemoglobin within a red blood cell, but not the absolute weight (picograms). It’s a calculated value derived from HCT, MCH, and RBC count.

Answer: MCHC

MCHC (Mean Corpuscular Hemoglobin Concentration) reflects the percentage saturation of a red blood cell with hemoglobin. The provided reference range (32-36%) represents the typical hemoglobin concentration within healthy red blood cells.

The other options are incorrect:

• HCT (Hematocrit): HCT indicates the percentage of red blood cells in whole blood, not the hemoglobin saturation within those cells.
• MCV (Mean Corpuscular Volume): MCV reflects the average size of red blood cells, not their hemoglobin saturation.
• MCH (Mean Corpuscular Hemoglobin): MCH represents the average weight of hemoglobin per red blood cell, but not the percentage saturation (concentration).

Answer: inhibits DNA synthesis by acting as a ribonucleotide

Hydroxyurea inhibits the enzyme ribonucleotide reductase, which is involved in DNA synthesis, by reducing ribonucleotides to deoxyribonucleotides. This inhibition leads to decreased DNA synthesis, particularly affecting rapidly dividing cells such as those found in bone marrow, which can be beneficial in certain hematologic conditions like sickle cell disease and myeloproliferative disorders.

The other options are incorrect:

• Decreases nitric oxide: This statement is incorrect. Hydroxyurea has been shown to increase nitric oxide levels, which is believed to contribute to its therapeutic effects, particularly in sickle cell disease, by improving blood flow and reducing vaso-occlusive events.
• Increases neutrophil and monocytes: This statement is incorrect. While hydroxyurea can increase the production of fetal hemoglobin and decrease the number of reticulocytes, it does not directly affect the production of neutrophils or monocytes.

Answer: Coombs test

The Coombs test, also known as direct antiglobulin test (DAT) or indirect antiglobulin test (IAT), is used to detect the presence of antibodies or complement proteins that are bound to the surface of red blood cells (RBCs). This test is helpful in diagnosing hemolytic anemias, where the immune system mistakenly attacks and destroys red blood cells. The Coombs test can differentiate between immune-mediated hemolytic anemias (positive Coombs test) and non-immune-mediated hemolytic anemias (negative Coombs test).

The other options are incorrect:

• Genetic testing: While genetic testing can be useful in diagnosing certain types of hemolytic anemias, such as hereditary spherocytosis or glucose-6-phosphate dehydrogenase (G6PD) deficiency, it is not a primary test for detecting hemolytic anemia in general.
• Peripheral blood smear (PBS): A peripheral blood smear is a valuable diagnostic tool in evaluating various types of anemias, including hemolytic anemias.
• Schilling test: The Schilling test is used to evaluate vitamin B12 absorption in the gastrointestinal tract and is not relevant for detecting hemolytic anemia.

Answer: All of the above

All the listed options (thromboembolism, PAD, pulmonary embolism) are complications that can arise due to clot/thrombus formation in the blood circulation and can be fatal.

• Thromboembolism: This is a general term for a blood clot (thrombus) that breaks loose and travels through the bloodstream (embolus). This embolus can lodge in a distant blood vessel, blocking blood flow and potentially causing tissue damage or death in the affected organ or area.
• PAD (Peripheral Arterial Disease): PAD is a condition caused by a buildup of plaque in the arteries that supply blood to the legs and feet. This can lead to the formation of blood clots that can further restrict blood flow and increase the risk of tissue death (gangrene) in the extremities.
• Pulmonary Embolism (PE): A PE occurs when a blood clot travels to the lungs and blocks a pulmonary artery. This can be a life-threatening condition that can lead to sudden death if a large clot blocks a major artery.

Answer: 120

The average lifespan of a red blood cell (RBC) in humans is approximately 120 days. During this time, red blood cells circulate throughout the body, delivering oxygen to tissues and carrying away carbon dioxide. As they age, they become less efficient and are eventually removed from circulation by the spleen and liver.

The other options are incorrect:

• 200: This is too long for a typical RBC lifespan.
• 100 & 80: These values are a bit on the shorter side compared to the average lifespan of 120 days.

Answer: Stage 0

In the Rai Staging System for chronic lymphocytic leukemia (CLL), Stage 0 refers to a low-risk stage where there is absolute lymphocytosis (>5000/mm^3) without any other significant signs or symptoms such as lymph node enlargement (adenopathy), enlarged liver or spleen (hepatosplenomegaly), anemia, or thrombocytopenia.

The other options are incorrect:

• Stage I: Stage I in the Rai Staging System typically indicates lymphocytosis with lymphadenopathy (enlarged lymph nodes), but without hepatosplenomegaly, anemia, or thrombocytopenia. It is a higher stage than Stage 0.
• Stage II: Stage II in the Rai Staging System indicates lymphocytosis with lymphadenopathy and hepatosplenomegaly, but without anemia or thrombocytopenia. It is a higher stage than Stage 0.
• Stage III: Stage III in the Rai Staging System indicates lymphocytosis with anemia (hemoglobin < 11 g/dL) in addition to the features of Stage II (lymphadenopathy and hepatosplenomegaly). It is a higher stage than Stage 0.

Answer: chemotherapy

While some patients with Rai stage 0 or I CLL may not require immediate treatment due to the slow progression, Rai stage II typically warrants treatment with chemotherapy.

The other options are incorrect:

• Antibiotics: Antibiotics are used to treat bacterial infections, not CLL, which is a type of cancer.
• Antivirals: Antivirals target viruses, and CLL isn’t caused by a virus.
• Rest: While getting enough rest is important for overall health, it’s not the primary treatment for CLL.

Answer: older adults

Chronic lymphocytic leukemia (CLL) is most commonly diagnosed in older adults, particularly those over the age of 50 or 60 years. It is rare in young adults and is much more prevalent in the elderly population.

The other options are incorrect:

• Young adults: While chronic lymphocytic leukemia (CLL) can occur in young adults, it is much less common in this age group compared to older adults. CLL primarily affects older individuals, with the median age at diagnosis typically in the 70s.

Answer: lymphocytosis

Chronic Lymphocytic Leukemia (CLL) is a cancer of the B lymphocytes, a type of white blood cell. The hallmark feature of CLL is an increased number of mature but abnormal B lymphocytes in the peripheral blood and bone marrow. This is termed lymphocytosis.

The other options are incorrect:

• Lymphocytopenia: This refers to a decreased number of lymphocytes in the blood, which is the opposite of what occurs in CLL.

Answer: Orthochromic Normoblast

The most mature normoblast is the Orthochromic Normoblast. It is the stage of erythropoiesis where the cell has nearly completed its maturation process. Orthochromic normoblasts have a smaller nucleus and a smaller amount of cytoplasm compared to earlier stages, and their cytoplasm is becoming more pinkish due to the increasing concentration of hemoglobin.

The other options are incorrect:

• Basophilic Normoblast: Basophilic normoblasts are an earlier stage in erythropoiesis compared to orthochromic normoblasts. They have a larger nucleus and more basophilic cytoplasm.
• Pronormoblast: Pronormoblasts are the earliest recognizable stage of erythropoiesis. They have a large nucleus and abundant basophilic cytoplasm.
• Polychromatic Normoblast: Polychromatic normoblasts are a less mature stage compared to orthochromic normoblasts.

Answer: Stage II

In the Rai Staging System for chronic lymphocytic leukemia (CLL), Stage II is characterized by absolute lymphocytosis with either hepatomegaly or splenomegaly, with or without lymphadenopathy. This stage indicates a moderate risk level in CLL prognosis.

The other options are incorrect:

• Stage 0: This stage only includes absolute lymphocytosis without any other signs like enlarged organs or lymph nodes.
• Stage III: This stage requires lymphocytosis with anemia (low red blood cell count) in addition to possible enlargement of the liver, spleen, or lymph nodes.
• Stage IV: This is the most advanced stage and requires lymphocytosis with low platelet count (thrombocytopenia) along with possible enlargement of organs or lymph nodes.

Answer: Stage 0

The Rai Staging System classifies CLL based on progressive signs. Stage 0 represents the earliest stage with only absolute lymphocytosis (high lymphocyte count in peripheral blood) and no other abnormalities. This means there’s no enlargement of lymph nodes (lymphadenopathy), liver (hepatomegaly), spleen (splenomegaly), anemia, or thrombocytopenia.

The other options are incorrect:

• Stage I: This stage requires lymphocytosis along with lymphadenopathy, indicating involvement beyond the blood.
• Stage II: This stage includes lymphocytosis with either hepatomegaly or splenomegaly, indicating organ involvement.
• Stage III: This is a more advanced stage with lymphocytosis and anemia, suggesting bone marrow issues affecting red blood cell production.

Answer: soccer-ball

In Chronic Lymphocytic Leukemia (CLL), lymphocytes typically appear small or slightly larger than normal, with hyper-condensed nuclear chromatin. These lymphocytes can resemble soccer-balls in appearance. The hyper-condensed chromatin can cause the nuclei to appear densely stained and often irregular, contributing to the characteristic appearance of CLL cells. “Smudge cells,” also known as “basket cells” or “basket smears,” are common due to the fragility of CLL cells, where the delicate cells rupture during slide preparation.

The other options are incorrect:

• Basketball: This option is incorrect. Basketball is not used to describe the appearance of CLL lymphocytes.
• Football: Football is not used to describe the appearance of CLL lymphocytes.
• Tennis-ball: Tennis-ball is not used to describe the appearance of CLL lymphocytes.

Answer: Tense

The tense form of the hemoglobin (Hb) molecule has the lowest affinity for oxygen. In the tense state, the hemoglobin molecule has a decreased ability to bind oxygen molecules. This occurs in tissues with low oxygen levels, where the hemoglobin releases oxygen to meet the metabolic demands of the tissues.

The other options are incorrect:

• Relaxed: The relaxed form of the hemoglobin molecule has a higher affinity for oxygen. In the relaxed state, hemoglobin binds oxygen more readily, such as in the lungs where oxygen levels are high.
• Arterial: Arterial blood typically contains oxygenated hemoglobin, which is in the relaxed form and has a higher affinity for oxygen.
• Venous: Venous blood typically contains deoxygenated hemoglobin, which is in the tense form and has a lower affinity for oxygen compared to arterial blood.

Answer: 2.5

To calculate the total white blood cell count (WBC) per liter (x10^9/L), you need to use the formula:

𝑊𝐵𝐶=(𝐴𝑣𝑒𝑟𝑎𝑔𝑒 𝑐𝑜𝑢𝑛𝑡 𝑜𝑓 𝑐𝑒𝑙𝑙𝑠 𝑝𝑒𝑟 𝑠𝑞𝑢𝑎𝑟𝑒)×(𝐷𝑖𝑙𝑢𝑡𝑖𝑜𝑛 𝑓𝑎𝑐𝑡𝑜𝑟)×(𝐷𝑒𝑝𝑡ℎ 𝑓𝑎𝑐𝑡𝑜𝑟)(𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑠𝑞𝑢𝑎𝑟𝑒𝑠 𝑐𝑜𝑢𝑛𝑡𝑒𝑑)WBC=(Number of squares counted)(Average count of cells per square)×(Dilution factor)×(Depth factor)​

Given that 100 cells were counted, and a 1:20 dilution was made, the dilution factor is 20. Since four corner squares on BOTH sides of the hemacytometer were counted, the number of squares counted is 8.

Therefore, the calculation is:

𝑊𝐵𝐶=(100 𝑐𝑒𝑙𝑙𝑠)×(20)×(1)(8)=250 𝑐𝑒𝑙𝑙𝑠/𝜇𝐿WBC=(8)(100 cells)×(20)×(1)​=250 cells/μL

To convert to cells per liter (x10^9/L), you divide by 103103, which gives:

𝑊𝐵𝐶=250103=0.25×109/𝐿=2.5×109/𝐿WBC=103250​=0.25×109/L=2.5×109/L

The other options are incorrect:

• 0.25: It seems to be the result of the calculation without converting the units to cells per liter.
• 5: It seems to be a miscalculation or misinterpretation of the correct answer.
• 10: It seems to be a miscalculation or misinterpretation of the correct answer.

Answer: Microtubules

Microtubules are a major component of the cytoskeleton, a network of fibers that provides structural support and shape to the cell. They are long, hollow tubes made of protein and play a crucial role in maintaining cell integrity, shape, and movement.

The other options are incorrect:

• Spindle Fibers: These are specialized microtubule structures that form during cell division (mitosis and meiosis) to separate chromosomes. While they play a role in cell organization during division, they are not responsible for maintaining the overall cell shape during the interphase (non-dividing) stage.
• Ribosomes: These are cellular structures responsible for protein synthesis. They are not involved in maintaining cell shape.
• Centrioles: These are structures involved in organizing microtubules during cell division. While they interact with microtubules, their primary function is in cell division, not maintaining overall cell shape.

Answer: End of 6th month

During fetal development, hematopoiesis (the process of blood cell formation) initially occurs in the yolk sac, then later shifts to the liver and spleen. By the end of the 6th month of fetal development, the bone marrow becomes the primary site of hematopoiesis. The bone marrow continues to be the primary site of hematopoiesis throughout adulthood.

The other options are incorrect:

2nd month: At this stage, the yolk sac is still the primary site. 5th month: While the fetal liver plays a major role during this month, bone marrow hasn’t become the primary site yet. End of 7th month: Bone marrow hematopoiesis is increasing significantly by this point, but it typically becomes the primary site by the end of the 6th month.

Answer: Only Erythroblasts

During the mesoblastic phase of hematopoiesis in the yolk sac, the primary cell type produced are erythroblasts. These are immature red blood cell precursors.

The other options are incorrect:

• Hb F, Hg A2, and Hg A: These are types of hemoglobin, the protein that carries oxygen in red blood cells. They are not directly produced in the yolk sac. Hemoglobin types are formed later in development and vary depending on the stage.
• Gower 1 and Gower 2 Hgb: These are specific types of embryonic hemoglobin produced by the primitive erythroblasts in the yolk sac. However, they are not the only cell type developed. Macrophages and megakaryocytes are also produced in small numbers during this phase.
• Portland Hgb: This is another type of embryonic hemoglobin produced by yolk sac erythroblasts. While a significant type, it’s not the only cell produced.

Answer: alpha and beta

Normal adult hemoglobin A (Hb A) consists of two alpha (α) globin chains and two beta (β) globin chains. These globin chains combine to form the functional tetrameric hemoglobin molecule, which carries oxygen in red blood cells.

The other options are incorrect:

Alpha and Epsilon: Epsilon chains are present in embryonic hemoglobin (Hb E) found during fetal development, not in adult Hb A. Alpha and Delta: Delta chains are present in a minor adult hemoglobin type called Hb A2, which contains two alpha and two delta chains. However, Hb A is the major adult hemoglobin and does not contain delta chains. Alpha and Brotherton: “Brotherton” is not a standard term used for any known globin chain in hemoglobin. It’s likely a misspelling or misremembered term.

Answer: Eosinophils

Allergic reactions often lead to an increase in the presence of eosinophils in the bloodstream and affected tissues. Eosinophils are a type of white blood cell that plays a crucial role in the immune response against parasitic infections and allergic reactions. They release various inflammatory mediators and enzymes, contributing to the inflammatory response associated with allergic reactions.

The other options are incorrect:

• Lymphocytes: While lymphocytes are a vital part of the immune system, they are not the primary cell type associated with the immediate inflammatory response in allergies.
• Neutrophils: These white blood cells are more involved in fighting bacterial infections and are not as prominent in allergic reactions.
• Monocytes: Monocytes are another type of white blood cell that can differentiate into other immune cells. While they may be involved in the later stages of an allergic response.

Answer: 2

1The Reticulocyte Production Index (RPI) is a measure of the bone marrow’s response to anemia (low red blood cell count). It takes into account both the percentage of reticulocytes (immature red blood cells) and the hematocrit (Hct), which reflects the red blood cell concentration in the blood.

The other options are incorrect:

• 3, 4, and 5: These values are higher than the calculated RPI (2.00). A higher RPI could indicate an increased bone marrow response, possibly due to more severe anemia or other factors influencing red blood cell production.

Answer: In two layers that are not symmetric in composition

The lipids in the RBC membrane are arranged in a specific structure called a phospholipid bilayer. This bilayer consists of two layers of phospholipid molecules.

The other options are incorrect:

• In chains beneath a protein exoskeleton: There is no protein exoskeleton surrounding the RBC membrane. Lipids and proteins are interwoven, but the lipids form the foundation of the bilayer structure.
• So that the hydrophobic portions are facing the plasma: While the hydrophobic tails do face away from the water, they are not directly exposed to the plasma. They are positioned within the inner leaflet of the bilayer.
• In a hexagonal lattice: The phospholipids don’t form a rigid hexagonal lattice structure. They have more flexibility within the bilayer, allowing for some movement and fluidity.pen_spark
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Answer: NADPH and reduced glutathione

The hexose monophosphate pathway in red blood cells increases the production of NADPH, which is essential for maintaining antioxidant defenses and reducing potential oxidative damage. It also contributes to the regeneration of reduced glutathione, further enhancing antioxidant capacity.

The other options are incorrect:

• Glucose and lactic acid: This pathway does not directly produce lactic acid in RBCs.
• 2,3-BPG and methemoglobin: The hexose monophosphate pathway does not synthesize 2,3-BPG or influence methemoglobin levels in RBCs.
• ATP and other purine metabolites: While ATP is generated in RBCs through glycolysis, it is not a direct product of the hexose monophosphate pathway. Similarly, this pathway does not produce other purine metabolites.

Answer: Loss of nucleus

Normal RBCs lack a nucleus. This absence of a nucleus limits their lifespan because they cannot replenish essential proteins or repair DNA damage over time, leading to their eventual breakdown.

The other options are incorrect:

• Loss of mitochondria: Mature RBCs have very few or no mitochondria, but this doesn’t directly limit their lifespan. They rely primarily on anaerobic glycolysis for energy.
• Increased flexibility of the cell membrane: While flexibility is important for RBCs to squeeze through capillaries, it’s not the primary factor limiting their lifespan.
• Reduction of Hb iron: Fluctuations in iron levels can affect RBC function, but it’s not the sole determinant of lifespan.

Answer: 95% Hb A, <3.5 % Hb A2, <1-2% Hb F

In adults, the normal distribution of hemoglobin variants is approximately 95% hemoglobin A (Hb A), less than 3.5% hemoglobin A2 (Hb A2), and less than 1-2% hemoglobin F (Hb F).

The other options are incorrect:

• 80-90% Hb A, 5-10% Hb A2, 1-5% Hb: This distribution does not accurately represent the typical proportions of hemoglobin variants in adults. The percentage of Hb A2 and Hb F is typically lower, and Hb A is usually higher.

Answer: 16

One multipotential stem cell can give rise to 16 erythrocytes through the process of erythropoiesis.

The other options are incorrect:

• 8: This number is incorrect. Erythropoiesis generates a larger number of erythrocytes from a single multipotential stem cell.
• 1: This option is incorrect. Erythropoiesis produces multiple erythrocytes from a single multipotential stem cell.
• 12: This number is incorrect. Erythropoiesis generates a larger number of erythrocytes from a single multipotential stem cell.

Answer: With a genes and B genes on seperate chromosomes, two a genes on one chromosome and one B gene on a different chromosome

In humans, the alpha and beta globin gene clusters are located on different chromosomes. There are two alpha-globin genes (α1 and α2) on chromosome 16, and there are typically one or two beta-globin genes (β, δ, and γ) on chromosome 11. This arrangement allows for independent regulation of alpha and beta globin chain production.

The other options are incorrect:

• Same chromosome with two each (αα & BB): While some duplicated genes exist within clusters, humans don’t have exactly two alpha and two beta genes on the same chromosome.
• Same chromosome with four each (αααα &BBBB): This isn’t the typical arrangement in humans.
• Separate chromosomes with four alpha and two beta: The number of alpha genes is typically two, not four.

Answer: Surrounding macrophages near the sinus membrane

In the bone marrow, RBC precursors (erythroblasts) are primarily located in close proximity to macrophages near the sinus membrane

The other options are incorrect:

• In the center of the hematopoietic cords: Hematopoietic cords contain blood vessels and support cells, but RBC precursors are not typically found concentrated in the center.
• Adjacent to megakaryocytes along the adventitial cell lining: While megakaryocytes (platelet precursors) are present in the bone marrow, RBC precursors are not specifically located right next to them. Their distribution is more widespread.
• Surrounding fat cells in apoptotic islands: Apoptotic islands are areas with clusters of dying cells, and fat cells are present in the bone marrow. However, RBC precursors are not concentrated solely around these regions.

Answer: Liver

In midfetal life (around months 2-5), the liver takes over as the primary source of blood cells. This is a critical stage after the yolk sac’s role diminishes and before bone marrow assumes the dominant position later in development (around the end of the 6th month).

The other options are incorrect:

• Bone marrow: Bone marrow becomes the primary source of blood cells after birth and in adults, but this transition happens later in fetal development.
• Spleen: The spleen is involved in immune function and blood cell storage/destruction but isn’t the main producer during midfetal life.
• Lymph Nodes: Lymph nodes are important for the immune system, but they don’t produce all types of blood cells in significant numbers at this stage.

Answer: Peripheral protein

While the question doesn’t explicitly mention it, the key component responsible for the shape, structure, and deformability of the erythrocyte membrane is the spectrin network, which is part of the cell’s cytoskeleton. Spectrin is a peripheral protein located on the cytoplasmic side of the membrane.

The other options are incorrect:

• Integral protein: Integral proteins span the lipid bilayer but don’t directly determine the overall cell shape and flexibility.
• Exterior lipid: The outer leaflet of the lipid bilayer interacts with the environment but lacks structural strength for defining cell shape.
• Interior lipid: The inner leaflet provides a foundation but doesn’t dictate shape and deformability.

Answer: Lymphocyte

Lymphocytes are unique among the listed cell types because they can mature in lymphoid organs like the thymus and lymph nodes in addition to the bone marrow. These organs play a crucial role in lymphocyte development and function within the immune system.

The other options are incorrect:

• Monocyte: Monocytes develop primarily in the bone marrow and differentiate into macrophages and dendritic cells in tissues throughout the body.
• Megakaryocyte: Megakaryocytes develop and mature exclusively in the bone marrow. They are responsible for producing platelets.
• Neutrophil: Neutrophils also develop and mature solely in the bone marrow. They are a type of white blood cell involved in the immune response.

Answer: transferrin-bound iron into erythrocytes

The transferrin receptor on the surface of erythrocytes (red blood cells) is responsible for capturing iron from transferrin, a protein carrier in the blood. This iron is then used for hemoglobin synthesis within the red blood cell.

The other options are incorrect:

• Iron out of duodenal cells from the intestinal lumen: Transferrin receptors are not present on intestinal cells. Iron absorption in the duodenum involves different transport mechanisms.
• Iron out of duodenal cells into the plasma: While iron does eventually reach the plasma after absorption, the transferrin receptor on erythrocytes helps remove it from transferrin in the circulation for use by the red blood cells.

Answer: Rheumatoid arthritis

Autoimmune disorders like rheumatoid arthritis can lead to decreased platelet count due to immune-mediated destruction of platelets, resulting in a condition called immune thrombocytopenia.

Incorrect Options:

1. Connective tissue disorders: While some connective tissue disorders may have an impact on blood clotting, they typically do not directly decrease platelet count.
2. Inflammatory bowel disease: Although inflammatory bowel disease can lead to various complications, it is not typically associated with decreased platelet count.
3. Tuberculosis: Tuberculosis primarily affects the lungs but does not directly cause a decrease in platelet count.

Answer: Severe thrombocytosis

A total platelet count (TPC) of ≥ 900,000/μL indicates severe thrombocytosis. Thrombocytosis is a condition characterized by an abnormally high number of platelets in the blood. Platelets are cells involved in blood clotting. In severe thrombocytosis, the increased platelet count raises the risk of blood clots forming in arteries or veins, potentially leading to serious complications like stroke, heart attack, or pulmonary embolism.

Incorrect Options:

• Mild thrombocytosis: Platelet count is lower than the range for mild thrombocytosis (450,000 to 600,000/μL).
• Moderate thrombocytosis: Platelet count is lower than the range for moderate thrombocytosis (600,000 to 1,000,000/μL).
• Very severe thrombocytosis: Platelet count is lower than the range for very severe thrombocytosis (> 1,500,000/μL).