1. Blood is a ___________.
A) Muscle tissue
B) Connective tissue
C) Nervous tissue
D) Epithelial tissue
Answer: B
Explanation: Blood is a fluid connective tissue that circulates nutrients and wastes.
2. What percentage of human body weight is blood?
A) 2–3%
B) 7–8%
C) 12–15%
D) 20%
Answer: B
Explanation: In an adult, blood accounts for about 7–8% of body weight.
3. The average volume of blood in a healthy adult is___________.
A) 2–3 liters
B) 4–6 liters
C) 7–8 liters
D) 9–10 liters
Answer: B
Explanation: Adult humans normally have 4–6 liters of blood.
4. Blood consists of plasma and___________.
A) Water only
B) Corpuscles (cells)
C) Enzymes only
D) Salts only
Answer: B
Explanation: Blood = plasma (55%) + cells (45%).
5. Plasma forms about what percentage of blood?
A) 25%
B) 45%
C) 55%
D) 75%
Answer: C
Explanation: Plasma makes up the liquid portion, about 55% of blood.
6. The main component of plasma is___________.
A) Proteins
B) Water
C) Salts
D) Hormones
Answer: B
Explanation: Plasma is ~90–92% water.
7. Which proteins are abundant in plasma?
A) Albumin, globulin, fibrinogen
B) Myosin, actin
C) Hemoglobin, myoglobin
D) Collagen, elastin
Answer: A
Explanation: Plasma proteins perform transport, defense, and clotting functions.
8. The most abundant plasma protein is___________.
A) Albumin
B) Globulin
C) Fibrinogen
D) Hemoglobin
Answer: A
Explanation: Albumin maintains osmotic balance and regulates fluid movement.
9. Which plasma protein helps in blood clotting?
A) Albumin
B) Globulin
C) Fibrinogen
D) Insulin
Answer: C
Explanation: Fibrinogen converts into fibrin threads during clot formation.
10. Globulins in plasma function mainly as___________.
A) Hormones
B) Enzymes
C) Antibodies
D) Transport pigments
Answer: C
Explanation: Globulins act as immunoglobulins for defense against infections.
11. Which plasma component transports hormones and nutrients?
A) Water
B) Albumin
C) Globulins
D) Plasma itself
Answer: D
Explanation: Plasma carries glucose, amino acids, lipids, hormones, and waste.
12. Serum is plasma without___________.
A) Water
B) Proteins
C) Fibrinogen
D) Salts
Answer: C
Explanation: Serum = plasma − clotting factors (fibrinogen).
13. Normal pH of blood is___________.
A) 6.8
B) 7.0
C) 7.4
D) 8.0
Answer: C
Explanation: Blood is slightly alkaline (7.35–7.45).
14. Which gas is transported mainly dissolved in plasma as bicarbonate ions?
A) Oxygen
B) Carbon dioxide
C) Nitrogen
D) Helium
Answer: B
Explanation: ~70% of CO₂ is transported as bicarbonates in plasma.
15. Which mineral in plasma is essential for blood clotting?
A) Sodium
B) Potassium
C) Calcium
D) Iron
Answer: C
Explanation: Ca²⁺ is necessary for activation of clotting factors.
16. Which waste product is transported in plasma to kidneys?
A) Hemoglobin
B) Urea
C) Myosin
D) Collagen
Answer: B
Explanation: Urea is the main nitrogenous waste transported by plasma.
17. Which plasma lipoprotein is called “bad cholesterol”?
A) HDL
B) LDL
C) VLDL
D) Chylomicrons
Answer: B
Explanation: Low-Density Lipoprotein (LDL) deposits cholesterol in arteries.
18. Which plasma lipoprotein is called “good cholesterol”?
A) HDL
B) LDL
C) VLDL
D) Chylomicrons
Answer: A
Explanation: High-Density Lipoprotein removes cholesterol from tissues to liver.
19. Plasma helps maintain___________.
A) Osmotic balance
B) Acid-base balance
C) Temperature regulation
D) All of the above
Answer: D
Explanation: Plasma maintains homeostasis in the body.
20. Plasma makes up what percentage of total body water?
A) 10%
B) 25%
C) 55%
D) 70%
Answer: B
Explanation: Plasma holds about one-fourth of total body water.
21. The anticoagulant present naturally in blood is ___________.
A) Fibrinogen
B) Heparin
C) Prothrombin
D) Thrombin
Answer: B
Explanation: Heparin prevents clotting inside blood vessels.
22. Which organ synthesizes most plasma proteins?
A) Kidney
B) Liver
C) Pancreas
D) Spleen
Answer: B
Explanation: Albumin, fibrinogen, and most globulins are made in the liver.
23. Which component gives straw-yellow color to plasma?
A) Urochrome
B) Bilirubin
C) Hemoglobin
D) Carotene
Answer: B
Explanation: Bilirubin (from hemoglobin breakdown) gives plasma its pale yellow color.
24. What percentage of blood is formed elements (cells)?
A) 25%
B) 35%
C) 45%
D) 55%
Answer: C
Explanation: Blood contains ~45% cells (RBCs, WBCs, platelets).
25. Hematocrit refers to ___________.
A) Percentage of plasma
B) Percentage of RBCs in blood
C) Percentage of WBCs
D) Amount of hemoglobin
Answer: B
Explanation: Hematocrit (packed cell volume) is normally ~45%.
26. Red blood cells (RBCs) are also called___________.
A) Leukocytes
B) Thrombocytes
C) Erythrocytes
D) Lymphocytes
Answer: C
Explanation: RBCs are scientifically called erythrocytes, derived from Greek erythros (red).
27. The main function of RBCs is ___________.
A) Blood clotting
B) Transport of oxygen
C) Production of hormones
D) Immunity
Answer: B
Explanation: Hemoglobin in RBCs carries oxygen to tissues.
28. Average number of RBCs per cubic mm of blood in men is about ___________.
A) 2–3 million
B) 4–5 million
C) 5–6 million
D) 8–9 million
Answer: C
Explanation: Adult males have ~5–6 million RBCs per cubic mm.
29. Average number of RBCs per cubic mm of blood in women is about___________.
A) 2–3 million
B) 3.5–4.5 million
C) 5–6 million
D) 7–8 million
Answer: B
Explanation: Women have slightly fewer RBCs than men.
30. The average lifespan of a human RBC is___________.
A) 30 days
B) 60 days
C) 120 days
D) 200 days
Answer: C
Explanation: RBCs circulate for about 120 days before being destroyed in spleen/liver.
31. Which organ destroys old RBCs?
A) Kidney
B) Liver
C) Spleen
D) Pancreas
Answer: C
Explanation: The spleen is called the “graveyard of RBCs.”
32. Which organ produces most RBCs in adults?
A) Liver
B) Bone marrow
C) Spleen
D) Kidney
Answer: B
Explanation: Red bone marrow produces RBCs, WBCs, and platelets.
33. In the fetus, RBCs are mainly formed in the___________.
A) Kidney
B) Liver and spleen
C) Brain
D) Pancreas
Answer: B
Explanation: During fetal development, RBCs are produced by liver and spleen.
34. Which protein pigment gives RBCs their red color?
A) Myoglobin
B) Hemoglobin
C) Globulin
D) Albumin
Answer: B
Explanation: Hemoglobin is a red iron-containing pigment in RBCs.
35. Each hemoglobin molecule contains___________.
A) 2 iron atoms
B) 4 iron atoms
C) 6 iron atoms
D) 8 iron atoms
Answer: B
Explanation: Hemoglobin has 4 heme groups, each with one Fe²⁺ atom.
36. One gram of hemoglobin can carry about___________.
A) 0.5 ml oxygen
B) 1.34 ml oxygen
C) 2.0 ml oxygen
D) 3.0 ml oxygen
Answer: B
Explanation: Hemoglobin binds ~1.34 ml oxygen per gram.
37. The normal hemoglobin content in men is about___________.
A) 8–10 g/dl
B) 10–12 g/dl
C) 13–18 g/dl
D) 20–22 g/dl
Answer: C
Explanation: Normal male hemoglobin is ~13–18 g/dl of blood.
38. The normal hemoglobin content in women is about___________.
A) 10–12 g/dl
B) 12–16 g/dl
C) 16–20 g/dl
D) 20–24 g/dl
Answer: B
Explanation: Females have slightly lower hemoglobin than males.
39. Which vitamin is essential for RBC formation?
A) Vitamin A
B) Vitamin B12
C) Vitamin C
D) Vitamin D
Answer: B
Explanation: Vitamin B12 (cobalamin) is essential for erythropoiesis.
40. Which mineral is most essential for hemoglobin synthesis?
A) Calcium
B) Iron
C) Magnesium
D) Zinc
Answer: B
Explanation: Iron forms the central atom of heme, binding oxygen.
41. Deficiency of iron in diet causes___________.
A) Leukemia
B) Anemia
C) Hemophilia
D) Polycythemia
Answer: B
Explanation: Iron deficiency reduces hemoglobin, causing anemia.
42. Deficiency of Vitamin B12 causes___________.
A) Sickle cell anemia
B) Pernicious anemia
C) Aplastic anemia
D) Hemophilia
Answer: B
Explanation: Lack of Vitamin B12 impairs RBC maturation.
43. Abnormal sickle-shaped RBCs occur in___________.
A) Leukemia
b) Thalassemia
C) Sickle cell anemia
D) Hemophilia
Answer: C
Explanation: Genetic mutation produces abnormal hemoglobin S → sickle-shaped RBCs.
44. Polycythemia is a condition of___________.
A) Excess RBCs
B) Low RBCs
C) No WBCs
D) Low platelets
Answer: A
Explanation: Polycythemia causes abnormally high RBC count, increasing blood viscosity.
45. Mature RBCs in humans lack___________.
A) Mitochondria only
B) Nucleus only
C) Both nucleus and mitochondria
D) Cell membrane
Answer: C
Explanation: Lack of nucleus and mitochondria allows more space for hemoglobin.
46. Average diameter of a human RBC is___________.
A) 2–3 µm
B) 5–6 µm
C) 7–8 µm
D) 10–12 µm
Answer: C
Explanation: Human RBCs are ~7.2 µm in diameter.
47. The shape of human RBC is ___________.
A) Spherical
B) Oval
C) Biconcave disc
D) Flat sheet
Answer: C
Explanation: Biconcave shape increases surface area for gas exchange.
48. The hormone that stimulates RBC production is ___________.
A) Insulin
B) Erythropoietin
C) Adrenaline
D) Thyroxine
Answer: B
Explanation: Erythropoietin (from kidneys) stimulates bone marrow to produce RBCs.
49. Which organ secretes erythropoietin?
A) Liver
B) Kidney
C) Spleen
D) Pancreas
Answer: B
Explanation: Kidneys sense low oxygen and release erythropoietin.
50. The condition of abnormally low RBC count is called ___________.
A) Leukopenia
B) Anemia
C) Thrombocytopenia
D) Leukemia
Answer: B
Explanation: Anemia results from insufficient RBCs or hemoglobin.
51. White blood cells (WBCs) are also called ___________.
A) Erythrocytes
B) Thrombocytes
C) Leukocytes
D) Lymphocytes
Answer: C
Explanation: WBCs (leukocytes) defend the body against infections.
52. The average number of WBCs per cubic mm of blood is ___________.
A) 500–1,000
B) 1,000–2,000
C) 5,000–10,000
D) 50,000–100,000
Answer: C
Explanation: Normal adult blood contains 5,000–10,000 WBCs per cubic mm.
53. The lifespan of WBCs is usually ___________.
A) Few hours to few days
B) 120 days
C) Several months
D) Several years
Answer: A
Explanation: Most WBCs live only a few hours to days, except some memory lymphocytes.
54. WBCs are formed mainly in ___________.
A) Kidney
B) Bone marrow and lymph nodes
C) Spleen only
D) Pancreas
Answer: B
Explanation: Bone marrow produces most WBCs; lymphoid tissues (lymph nodes, spleen) help in maturation.
55. Which type of WBCs are most abundant?
A) Eosinophils
B) Basophils
C) Neutrophils
D) Lymphocytes
Answer: C
Explanation: Neutrophils (60–70% of WBCs) fight bacterial infections.
56. Which WBCs are called “soldiers of the body”?
A) Lymphocytes
B) Neutrophils
C) Monocytes
D) Basophils
Answer: B
Explanation: Neutrophils engulf bacteria by phagocytosis.
57. Which WBCs produce antibodies?
A) Monocytes
B) Lymphocytes (B-cells)
C) Neutrophils
D) Eosinophils
Answer: B
Explanation: B lymphocytes produce antibodies for immune defense.
58. T-lymphocytes are mainly involved in ___________.
A) Blood clotting
B) Cell-mediated immunity
C) Oxygen transport
D) Antibody production
Answer: B
Explanation: T-cells attack virus-infected and cancer cells.
59. Which WBCs are called “scavengers of the body”?
A) Neutrophils
B) Basophils
C) Monocytes
D) Eosinophils
Answer: C
Explanation: Monocytes engulf dead cells and pathogens.
60. Which WBCs are responsible for allergic reactions?
A) Neutrophils
B) Basophils
C) Monocytes
D) Lymphocytes
Answer: B
Explanation: Basophils release histamine and heparin during allergy and inflammation.
61. Which WBCs are active against parasitic infections?
A) Eosinophils
B) Basophils
C) Lymphocytes
D) Monocytes
Answer: A
Explanation: Eosinophils fight parasites and mediate allergic responses.
62. A rise in eosinophil count indicates ___________.
A) Bacterial infection
B) Parasitic infection or allergy
C) Viral infection
D) Cancer
Answer: B
Explanation: High eosinophil count signals parasitic disease or allergic condition.
63. A rise in lymphocyte count is seen in ___________.
A) Viral infections
B) Bacterial infections
C) Fungal infections
D) Allergy
Answer: A
Explanation: Lymphocytosis is common in viral diseases like measles and mumps.
64. Which WBCs secrete histamine and heparin?
A) Monocytes
B) Basophils
C) Neutrophils
D) Eosinophils
Answer: B
Explanation: Basophils release histamine (inflammation) and heparin (anticoagulant).
65. The largest WBCs are ___________.
A) Neutrophils
B) Lymphocytes
C) Monocytes
D) Eosinophils
Answer: C
Explanation: Monocytes are the largest WBCs and transform into macrophages.
66. Platelets are also called ___________.
A) Leukocytes
B) Thrombocytes
C) Lymphocytes
D) Erythrocytes
Answer: B
Explanation: Platelets (thrombocytes) are fragments of megakaryocytes.
67. Average platelet count per cubic mm of blood is ___________.
A) 10,000–20,000
B) 50,000–100,000
C) 1–2 lakh
D) 1–2 million
Answer: C
Explanation: Normal platelet count is 1.5–4.5 lakhs per cubic mm.
68. The lifespan of platelets is ___________.
A) 5–9 days
B) 10–20 days
C) 30 days
D) 120 days
Answer: A
Explanation: Platelets survive about a week in circulation.
69. Platelets are produced in ___________.
A) Kidney
B) Liver
C) Bone marrow
D) Spleen
Answer: C
Explanation: Platelets are formed in red bone marrow from megakaryocytes.
70. Main function of platelets is ___________.
A) Transport of oxygen
B) Blood clotting
C) Immunity
D) Hormone transport
Answer: B
Explanation: Platelets release clotting factors initiating coagulation.
71. Which vitamin is essential for platelet function in clotting?
A) Vitamin A
B) Vitamin B12
C) Vitamin C
D) Vitamin K
Answer: D
Explanation: Vitamin K helps synthesize prothrombin, crucial for clotting.
72. Deficiency of platelets is called ___________.
A) Leukopenia
B) Anemia
C) Thrombocytopenia
D) Leukocytosis
Answer: C
Explanation: Thrombocytopenia causes bleeding tendency due to low platelet count.
73. Which disease is caused by failure of blood to clot due to absence of clotting factors?
A) Leukemia
B) Hemophilia
C) Anemia
D) Thrombocytosis
Answer: B
Explanation: Hemophilia is a genetic disorder where clotting factor VIII/IX is absent.
74. The disease of uncontrolled abnormal increase in WBCs is ___________.
A) Anemia
B) Leukemia
C) Hemophilia
D) Polycythemia
Answer: B
Explanation: Leukemia is called blood cancer, due to uncontrolled WBC production.
75. Which organ stores and destroys platelets?
A) Kidney
B) Liver
C) Spleen
D) Pancreas
Answer: C
Explanation: The spleen acts as a reservoir for platelets and destroys old ones.
76. The ABO blood group system was discovered by ___________.
A) Landsteiner
B) Harvey
C) Pavlov
D) Malpighi
Answer: A
Explanation: Karl Landsteiner discovered ABO blood groups in 1901.
77. Which antigen is present in blood group A?
A) Antigen B
B) Antigen A
C) Antigen AB
D) No antigen
Answer: B
Explanation: Blood group A has antigen A on RBCs and anti-B antibody in plasma.
78. Which antibodies are present in blood group B?
A) Anti-A
B) Anti-B
C) Anti-AB
D) No antibody
Answer: A
Explanation: Blood group B has antigen B and anti-A antibodies.
79. Which blood group has no antibodies in plasma?
A) A
B) B
C) O
D) AB
Answer: D
Explanation: AB blood group has both antigens but no antibodies → universal recipient.
80. Which blood group has no antigens on RBCs?
A) A
B) B
C) O
D) AB
Answer: C
Explanation: O blood group lacks both A and B antigens but has anti-A and anti-B antibodies.
81. Universal donor blood group is ___________.
A) A+
B) AB+
C) O−
D) AB−
Answer: C
Explanation: O− has no A, B, or Rh antigens, hence universal donor.
82. Universal recipient blood group is ___________.
A) A+
B) AB+
C) O+
D) B+
Answer: B
Explanation: AB+ has all antigens, hence can receive from all groups.
83. The Rh factor was discovered in ___________.
A) Rabbits
B) Rhesus monkeys
C) Rats
D) Horses
Answer: B
Explanation: Rh factor was first observed in rhesus monkeys.
84. The most common blood group in India is ___________.
A) A
B) B
C) O
D) AB
Answer: C
Explanation: O group is most common in Indian population.
85. Blood clotting normally occurs in about ___________.
A) 10–15 seconds
B) 3–6 minutes
C) 20–30 minutes
D) 1 hour
Answer: B
Explanation: Normal clotting time is ~5 minutes.
86. The enzyme that converts fibrinogen into fibrin is ___________.
A) Thrombin
B) Prothrombin
C) Plasmin
D) Pepsin
Answer: A
Explanation: Thrombin is the active enzyme that forms insoluble fibrin threads.
87. Prothrombin is converted to thrombin in presence of ___________.
A) Calcium ions
B) Vitamin K
C) Platelet factors
D) All of the above
Answer: D
Explanation: Conversion of prothrombin requires Ca²⁺, vitamin K, and platelet factors.
88. Which vitamin deficiency leads to delayed clotting?
A) Vitamin A
B) Vitamin B12
C) Vitamin K
D) Vitamin D
Answer: C
Explanation: Vitamin K is essential for synthesis of prothrombin.
89. Natural anticoagulant in blood is ___________.
A) Thrombin
B) Heparin
C) Prothrombin
D) Fibrinogen
Answer: B
Explanation: Heparin prevents unwanted intravascular clotting.
90. The condition of low platelet count is ___________.
A) Anemia
B) Leukopenia
C) Thrombocytopenia
D) Leukocytosis
Answer: C
Explanation: Low platelets increase bleeding tendency.
91. Hemophilia is caused by deficiency of ___________.
A) Hemoglobin
B) RBCs
C) Clotting factors (Factor VIII or IX)
D) WBCs
Answer: C
Explanation: Hemophilia is a genetic disease with defective clotting proteins.
92. Which type of genetic disease is hemophilia?
A) Autosomal dominant
B) Autosomal recessive
C) X-linked recessive
D) Y-linked dominant
Answer: C
Explanation: Hemophilia is inherited through the X chromosome.
93. Which blood disorder is also called “blood cancer”?
A) Hemophilia
B) Leukemia
C) Thrombocytopenia
D) Sickle cell anemia
Answer: B
Explanation: Leukemia is uncontrolled proliferation of abnormal WBCs.
94. The disease caused by abnormally shaped RBCs is ___________.
A) Thalassemia
B) Leukemia
C) Hemophilia
D) Sickle cell anemia
Answer: D
Explanation: A genetic defect in hemoglobin causes sickle-shaped RBCs.
95. Thalassemia is a disorder of ___________.
A) Platelets
B) Hemoglobin synthesis
C) WBCs
D) Plasma proteins
Answer: B
Explanation: Thalassemia is an inherited defect in globin chain formation.
96. Excess breakdown of RBCs leads to ___________.
A) Jaundice
B) Anemia
C) Polycythemia
D) Leukemia
Answer: A
Explanation: Excess bilirubin from RBC breakdown causes yellowing of skin and eyes.
97. Which organ is known as “graveyard of RBCs”?
A) Kidney
B) Liver
C) Spleen
D) Pancreas
Answer: C
Explanation: Spleen destroys old and worn-out RBCs.
98. Which blood test is used to measure hemoglobin?
A) Lipid profile
B) CBC (Complete Blood Count)
C) ESR
D) BUN
Answer: B
Explanation: CBC test estimates hemoglobin, RBC count, WBC count, and platelets.
99. The medical term for increased WBC count is ___________.
A) Leukopenia
B) Leukocytosis
C) Thrombocytosis
D) Polycythemia
Answer: B
Explanation: Leukocytosis is a rise in WBC count due to infections.
100. Blood transfusion is safest when ___________.
A) Blood group is matched
B) Donor is healthy
C) Cross-matching is done
D) All of the above
Answer: D
Explanation: Compatibility tests (ABO, Rh), donor health, and cross-matching are essential for safe transfusion.