Blood and Immunity Practice Questions

Q: In fetal life, in which of the following sites are red blood cells NOT produced?

Lymph node. ***Lymph node*** - **Lymph nodes** are not normal sites of fetal erythropoiesis; they primarily support **lymphopoiesis** and immune filtration rather than red blood cell production. - Fetal erythropoiesis proceeds through the **yolk sac**, **liver**, **spleen**, and **bone marrow**, whereas lymph nodes are not included in this developmental sequence. *Spleen* - The **spleen** contributes to fetal erythropoiesis, particularly during the **third to sixth months**, when it acts as a hematopoietic organ. - Although primarily a **secondary lymphoid organ**, the fetal spleen also supports blood-cell production and therefore is not the correct choice. *Bone marrow* - **Bone marrow** begins significant erythropoiesis around the **20th week** of gestation and becomes the dominant site by the late fetal period. - Its increasing role during the **myeloid stage** means bone marrow is a recognized fetal site of red blood cell production, not the answer. *Liver* - The **liver** is the principal fetal erythropoietic organ during the **second trimester**, with activity peaking around the fifth month. - Because hepatic erythropoiesis is a major stage of normal **fetal hematopoiesis**, the liver is not the site excluded by the question.

Q: What is the first cell in the development of red blood cells?

Proerythroblast. ***Proerythroblast*** - The **proerythroblast** is the **first morphologically identifiable committed erythroid precursor** in red blood cell development. - It is a large cell with a **prominent nucleus**, visible nucleoli, and a thin rim of basophilic cytoplasm before maturation into successive normoblast stages. *Basophilic erythroblast* - **Basophilic erythroblast** is the **second morphologically identifiable stage** of erythropoiesis, developing after the proerythroblast. - Its intense **cytoplasmic basophilia** reflects abundant RNA; therefore, it cannot be the first recognizable erythroid precursor. *Reticulocyte* - **Reticulocytes** are **immature red cells** formed after nuclear extrusion during the late normoblast stage. - They are a **penultimate stage** that remains briefly in bone marrow before entering the circulation, so they develop later than proerythroblasts. *Intermediate normoblast* - The **intermediate normoblast**, or polychromatophilic erythroblast, is the **third erythroid stage** after the proerythroblast and basophilic erythroblast. - Its **grayish-purple cytoplasm** contains both RNA and hemoglobin, indicating a later stage rather than the first recognizable precursor.

Q: Which of the following promotes rouleaux formation?

Fibrinogen. ***Fibrinogen*** - **Fibrinogen** promotes rouleaux by reducing RBC surface repulsion and acting as a bridging plasma protein between adjacent cells. - Increased **fibrinogen and globulins** during inflammation enhance rouleaux formation, contributing to an increased erythrocyte sedimentation rate. *Zeta potential on RBC membrane* - **Zeta potential** is the negative electrostatic charge on the RBC membrane, largely due to sialic acid, and normally causes adjacent RBCs to repel one another. - A **reduction in zeta potential** promotes rouleaux formation; the intact potential itself therefore prevents aggregation rather than promoting it. *Biconcave shape of RBC* - The **biconcave shape** provides a broad surface that may facilitate contact between RBCs, but it is not the principal plasma factor promoting rouleaux. - Rouleaux primarily depends on **plasma proteins overcoming electrostatic repulsion**; therefore, biconcavity is not the best answer. *Albumin* - **Albumin** is relatively small and negatively charged, so it does not effectively bridge RBCs or promote their stacking. - Unlike **fibrinogen**, albumin tends to help maintain separation between RBCs and therefore is not associated with increased rouleaux formation.

Q: What is true about the Rh factor?

There are no natural anti-Rh antibodies in serum.. ***There are no natural anti-Rh antibodies in serum.*** - Unlike ABO antibodies, **anti-Rh antibodies are not naturally occurring** in serum; they develop only after exposure to Rh-positive red cells. - An Rh-negative individual may become **sensitized** through transfusion or pregnancy, subsequently producing anti-D antibodies that can cause hemolytic disease. *It is seen only in females.* - The Rh factor is an **inherited red-cell antigen** found in both males and females, so it is not restricted to one sex. - Rh inheritance is **autosomal**, rather than sex-linked; therefore, sex does not determine whether an individual is Rh-positive or Rh-negative. *Approximately 15% of Indians are Rh positive.* - Approximately **93–95% of Indians** are Rh-positive, while only about 5–7% are Rh-negative; therefore, 15% is incorrect for this population. - A prevalence near **15% Rh-negative** is associated more closely with Caucasian populations, not with the Indian population described here. *The D antigen is the least potent Rh antigen.* - The **D antigen** is the most potent and highly immunogenic antigen in the Rh system, not the least potent. - Presence or absence of the **D antigen** determines Rh-positive or Rh-negative status; its immunogenicity makes it especially important in transfusion and pregnancy.

Q: Which cell does not differentiate in the bone marrow?

T lymphocyte. ***T lymphocyte*** - **T lymphocytes** originate from hematopoietic stem cells in the **bone marrow**, but pro-T cells migrate to the thymus before completing differentiation and maturation. - In the **thymus**, they undergo thymic education, acquire T-cell receptors, develop self-tolerance, and mature into CD4+ or CD8+ cells; therefore, they do not differentiate in bone marrow. *Basophil* - **Basophils** arise from myeloid progenitors and complete granulopoiesis, including maturation from myeloblasts to mature cells, within the **bone marrow**. - Because mature basophils are released into peripheral blood after marrow development, they do not fit the exception involving **T-cell maturation** in the thymus. *Neutrophil* - **Neutrophils** develop through myelopoiesis in the **bone marrow**, progressing from myeloblasts to mature segmented granulocytes before entering circulation. - Their differentiation is therefore completed in the **bone marrow**, unlike pro-T cells, which migrate to the thymus for maturation. *B lymphocyte* - **B lymphocytes** undergo both production and maturation within the **bone marrow**, distinguishing them from T lymphocytes. - After becoming mature in the **bone marrow**, B cells migrate to secondary lymphoid organs, so they do not represent the exception asked about.

Q: Prothrombin Time (PT) detects deficiency of all the following clotting factors EXCEPT?

VIII. ***VIII*** - **Factor VIII** belongs to the **intrinsic pathway**, not the extrinsic or common pathways assessed by PT. - Deficiency of **Factor VIII**, as in **Hemophilia A**, prolongs aPTT while generally leaving PT unaffected; therefore, PT does not detect it. *II* - **Factor II (prothrombin)** is part of the **common pathway**, whose activity contributes to clot formation measured by PT. - Deficiency of **Factor II** impairs conversion to thrombin and can prolong PT, so it is detected by this test. *VII* - **Factor VII** is the key factor in the **extrinsic pathway**, which PT specifically evaluates. - Because **Factor VII** has a short half-life, its deficiency can prolong PT and is often detected early in vitamin K deficiency or liver disease. *V* - **Factor V** participates in the **common pathway**, downstream of the extrinsic pathway assessed by PT. - A deficiency of **Factor V** reduces thrombin generation and prolongs PT; therefore, this factor is detected by the test.

Q: What is true of fetal hematopoiesis in the course of pregnancy?

Rise in Hemoglobin content. ***Rise in Hemoglobin content*** - **Hemoglobin concentration** progressively rises during gestation, from approximately 8–10 g/dL at 10 weeks to 14–20 g/dL at term, supporting increasing fetal oxygen requirements. - Increasing **erythropoietin production** by the fetal liver and later kidneys stimulates erythropoiesis in response to the relatively low intrauterine oxygen tension. *Decrease in blood volume* - Fetal **blood volume** increases approximately linearly with fetal weight throughout pregnancy rather than decreasing. - The expanding **vascular bed and placental circulation** require progressively greater circulating volume as the fetus grows. *Rise in reticulocyte count* - Although the **reticulocyte count** is very high early in gestation, it decreases as erythropoiesis matures, reaching approximately 3–5% at birth. - Thus, a **rise toward term** is incorrect; the early high count reflects rapid fetal red-cell production rather than the continuing gestational trend. *Rise in MCV* - Fetal red cells are initially **macrocytic**, with an MCV above 130 fL in the first trimester, but their size decreases during gestation. - The **MCV** reaches approximately 100–110 fL at birth, so it does not rise progressively throughout pregnancy.

Q: A father's blood group is 'A' and a mother's blood group is 'AB'. Which of the following blood groups is not possible in any of their child?

O. ***O*** - Group **O** requires genotype ii, meaning the child must receive a recessive i allele from both parents. - An AB mother has genotype **IᴬIᴮ** and cannot contribute i; therefore, no child of an A father and AB mother can have group O. *A* - Group **A** is possible when the child inherits Iᴬ from the AB mother and either Iᴬ or i from the father, producing IᴬIᴬ or Iᴬi. - The father may be homozygous or heterozygous for **Iᴬ**, while the mother can contribute Iᴬ; therefore, group A is not excluded. *B* - Group **B** is possible when the AB mother contributes Iᴮ and a heterozygous A father contributes i, producing genotype Iᴮi. - Although the father is phenotypically A, the genotype **Iᴬi** can carry the recessive i allele, allowing a child with group B. *AB* - Group **AB** is possible when the father contributes Iᴬ and the mother contributes Iᴮ, producing genotype IᴬIᴮ. - The ABO alleles **Iᴬ and Iᴮ are codominant**, so inheritance of one from each parent expresses both A and B antigens.

Q: Approximately what percentage of clot retraction is completed within 1 hour?

1 hour. ***1 hour*** - The mapped answer is **1 hour**, by which clot retraction is described as approximately complete through platelet **thrombosthenin** contraction of fibrin threads and expression of serum. - The stem asks for a **percentage**, but this option gives a **time duration**; therefore, the exact requested percentage cannot be established from the supplied choices. *2 hours* - **2 hours** is not the mapped time because the active phase of clot retraction is described as largely complete by approximately **60 minutes**. - Retraction may remain evident later, but the key distinguishing point is that **platelet-mediated contraction** has already reached its stated completion by 1 hour. *24 hours* - **24 hours** is not the mapped time for clot retraction; this interval is more associated with subsequent **fibrinolysis** and clot breakdown. - Plasmin-mediated **fibrinolysis** dissolves fibrin, whereas clot retraction is an earlier platelet-dependent process that contracts the clot and expels serum. *15 minutes* - **15 minutes** is too early because clot retraction has generally only **begun** after clot formation and has not achieved its stated maximum. - Although platelet contraction starts within minutes, substantial **fibrin-clot shrinkage** is described as developing over a longer period, reaching completion at approximately 1 hour.

Question 1

In fetal life, in which of the following sites are red blood cells NOT produced?

Accepted Answer

Lymph node

Answer

Liver

Answer

Spleen

Answer

Bone marrow

Question 2

What is the first cell in the development of red blood cells?

Accepted Answer

Proerythroblast

Answer

Intermediate normoblast

Answer

Reticulocyte

Answer

Basophilic erythroblast

Question 3

Which of the following promotes rouleaux formation?

Accepted Answer

Fibrinogen

Answer

Zeta potential on RBC membrane

Answer

Albumin

Answer

Biconcave shape of RBC

Question 4

What is true about the Rh factor?

Accepted Answer

There are no natural anti-Rh antibodies in serum.

Answer

It is seen only in females.

Answer

Approximately 15% of Indians are Rh positive.

Answer

The D antigen is the least potent Rh antigen.

Question 5

Which cell does not differentiate in the bone marrow?

Accepted Answer

T lymphocyte

Answer

B lymphocyte

Answer

Neutrophil

Answer

Basophil

Question 6

All of the following statements about Hepcidin are true EXCEPT:

Accepted Answer

Mice with enhanced hepcidin expression have elevated body iron stores.

Answer

It is a 25-amino acid peptide secreted by Kupffer cells.

Answer

It decreases duodenal absorption of iron.

Answer

It regulates the activity of transporters DMT-1 and ferroportin-1.

Question 7

Prothrombin Time (PT) detects deficiency of all the following clotting factors EXCEPT?

Accepted Answer

VIII

Answer

II

Answer

V

Answer

VII

Question 8

What is true of fetal hematopoiesis in the course of pregnancy?

Accepted Answer

Rise in Hemoglobin content

Answer

Rise in MCV

Answer

Rise in reticulocyte count

Answer

Decrease in blood volume

Question 9

A father's blood group is 'A' and a mother's blood group is 'AB'. Which of the following blood groups is not possible in any of their child?

Accepted Answer

O

Answer

A

Answer

B

Answer

AB

Question 10

Approximately what percentage of clot retraction is completed within 1 hour?

Accepted Answer

1 hour

Answer

24 hours

Answer

2 hours

Answer

15 minutes

Blood and Immunity — MCQs

Blood and Immunity — MCQs

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