Blood Composition Practice Questions
20 free Blood Composition practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
What percentage of blood is constituted by plasma, and what percentage of plasma is composed of water?
- A 45% and 90-92%
- B 55% and 70-75%
- C 55% and 90-92%
- D 45% and 80-85%
Correct answer: 55% and 90-92%
Plasma constitutes nearly 55 percent of the blood. Out of this plasma, 90-92 percent is water, while the remaining portion consists of proteins and other dissolved solutes.
Which plasma protein is primarily responsible for maintaining the osmotic balance of the blood?
- A Fibrinogen
- B Globulins
- C Serum albumin
- D Prothrombin
Correct answer: Serum albumin
Albumin is the most abundant plasma protein and is essential for maintaining the colloid osmotic pressure. This pressure prevents water from leaking out of the blood vessels into surrounding tissues.
The healthy adult human has an average RBC count of:
- A 2 million to 2.5 million per mm3
- B 5 million to 5.5 million per mm3
- C 1 million to 1.5 million per mm3
- D 7 million to 7.5 million per mm3
Correct answer: 5 million to 5.5 million per mm3
Red Blood Cells (Erythrocytes) are the most numerous cells in the blood. A healthy adult male typically has 5 to 5.5 million RBCs per cubic millimeter of blood.
What is the average lifespan of a Red Blood Cell, and where are they primarily destroyed?
- A 120 days; Liver
- B 100 days; Spleen
- C 120 days; Spleen
- D 80 days; Bone marrow
Correct answer: 120 days; Spleen
RBCs have an average lifespan of 120 days. After this period, they are destroyed in the spleen, which is often referred to as the 'graveyard of RBCs'.
Which of the following describes the shape of a mature human erythrocyte?
- A Nucleated and spherical in shape
- B Non-nucleated and biconcave
- C Nucleated and biconvex in shape
- D Non-nucleated and irregularly shaped
Correct answer: Non-nucleated and biconcave
Mature human RBCs lack a nucleus to provide more space for hemoglobin. Their biconcave shape increases the surface area-to-volume ratio, facilitating efficient gas exchange.
Which type of White Blood Cell (WBC) is the most abundant in human blood?
- A Monocytes
- B Basophils
- C Lymphocytes (B and T cells)
- D Neutrophils
Correct answer: Neutrophils
Neutrophils are the most numerous leukocytes, accounting for about 60-65 percent of the total WBC count. They are phagocytic cells that act as the first line of defense against infection.
Which of the following leucocytes are known for secreting histamine, serotonin, and heparin during inflammatory reactions?
- A Eosinophils
- B Basophils (granular WBCs)
- C Lymphocytes
- D Neutrophils
Correct answer: Basophils (granular WBCs)
Basophils are the least abundant WBCs (0.5-1%). They play a crucial role in inflammatory responses by releasing chemicals like histamine (vasodilator) and heparin (anticoagulant).
A person suffering from an allergic reaction or a parasitic infection is likely to show an increase in the count of:
- A Basophils (granular WBCs)
- B Neutrophils
- C Eosinophils
- D Monocytes (phagocytic WBCs)
Correct answer: Eosinophils
Eosinophils make up 2-3 percent of total WBCs. They are primarily involved in resisting infections and are associated with allergic reactions and parasitic infestations.
Identify the phagocytic cells among the following leucocytes:
- A Neutrophils and Monocytes
- B Basophils and Eosinophils
- C Lymphocytes and Monocytes
- D Neutrophils and Basophils
Correct answer: Neutrophils and Monocytes
Both neutrophils and monocytes are phagocytic cells that ingest and destroy foreign organisms entering the body. Monocytes constitute about 6-8 percent of total WBCs.
B and T forms of cells, responsible for the immune responses of the body, are types of:
- A Monocytes
- B Erythrocytes
- C Lymphocytes
- D Granulocytes
Correct answer: Lymphocytes
Lymphocytes constitute 20-25 percent of WBCs. They exist in two major forms, B-lymphocytes and T-lymphocytes, both of which are critical for specific immune responses.
Which blood component is produced from specialized cells in the bone marrow called megakaryocytes?
- A Erythrocytes
- B Leucocytes
- C Thrombocytes
- D Serum
Correct answer: Thrombocytes
Platelets, also known as thrombocytes, are cell fragments produced from megakaryocytes in the bone marrow. They play a vital role in blood clotting.
What is the normal range of platelets in the blood of a healthy individual?
- A 15,000 - 35,000 per mm3
- B 1,500,000 - 3,500,000 per mm3
- C 150,000 - 350,000 per mm3
- D 5,000 - 10,000 per mm3
Correct answer: 150,000 - 350,000 per mm3
Blood normally contains between 1,50,000 and 3,50,000 platelets per cubic millimeter. A significant reduction in this count can lead to clotting disorders and excessive blood loss.
Plasma without the clotting factors is called:
- A Lymph
- B Serum
- C Prothrombin
- D Heam
Correct answer: Serum
When clotting factors are removed from plasma, the remaining fluid is called serum. Serum contains all other proteins, electrolytes, and nutrients found in plasma but cannot clot.
Which of the following is an agranulocyte?
- A Neutrophil
- B Basophil
- C Lymphocyte
- D Eosinophil
Correct answer: Lymphocyte
Leucocytes are divided into granulocytes and agranulocytes. Lymphocytes and monocytes are agranulocytes, meaning they lack visible granules in their cytoplasm under a light microscope.
The total WBC count in a healthy human averages between:
- A 4,000 - 6,000 per mm3
- B 6,000 - 8,000 per mm3
- C 10,000 - 12,000 per mm3
- D 1,000 - 2,000 per mm3
Correct answer: 6,000 - 8,000 per mm3
Leucocytes are generally short-lived compared to RBCs. Their total count is much lower, averaging 6000-8000 per cubic millimeter of blood.
What is the amount of hemoglobin present in every 100 mL of blood in a healthy individual?
- A 6 - 8 grams per 100 mL
- B 12 - 16 grams
- C 18 - 20 grams
- D 25 - 30 grams
Correct answer: 12 - 16 grams
Hemoglobin is the red-colored, iron-containing complex protein in RBCs. A healthy individual has 12-16 grams of hemoglobin in every 100 mL of blood.
Globulins present in the blood plasma are primarily involved in:
- A Clotting of blood during injury
- B Osmotic balance
- C Defense mechanisms
- D Oxygen transport in blood
Correct answer: Defense mechanisms
Globulins, especially gamma-globulins, are primarily involved in the body's defense mechanisms. They form antibodies that help neutralize pathogens like bacteria and viruses.
Which of the following ions is required for the activation of various clotting factors in the plasma?
- A Na+
- B K+
- C Ca++
- D Mg++
Correct answer: Ca++
Calcium ions (Ca++) play a critical role in the blood coagulation cascade. They are necessary for the activation of several factors that convert prothrombin into thrombin.
Erythropoiesis (formation of RBCs) in adults occurs in the:
- A Spleen
- B Red bone marrow
- C Yellow bone marrow
- D Thymus
Correct answer: Red bone marrow
In adults, the red bone marrow is the primary site for the production of red blood cells. In the fetus, this process mainly occurs in the liver and spleen.
Which leucocyte has a multi-lobed nucleus and is often referred to as PMNL?
- A Monocyte
- B Lymphocyte
- C Neutrophil
- D Basophil
Correct answer: Neutrophil
Neutrophils are also called Polymorpho-nuclear Leucocytes (PMNL) because of their characteristic multi-lobed nucleus. This structural feature helps in their identification in blood smears.