12. Which statement is not correct for blood?
    (1) Mature RBC is of larger size as compare to its precursor cells
    (2) Platelets play important role in blood clotting
    (3) Neutrophils are major phagocytotic cells
    (4) Basophils are present in least amount

Introduction

Blood is a complex tissue composed of various specialized cells and components, each with distinct roles vital for health. However, some misunderstandings persist regarding characteristics of these cells, such as the size of mature red blood cells (RBCs) relative to their precursors, and the functions of platelets, neutrophils, and basophils. This article clarifies these aspects and explains why statement (1) regarding RBC size is not correct, while other statements about platelets, neutrophils, and basophils are accurate.

Statement (1): Mature RBC is Larger Than Its Precursors — Is This True?

The statement that mature RBCs are larger than their precursor cells is incorrect. During erythropoiesis (the process of red blood cell formation), precursor cells progressively decrease in size as they mature into erythrocytes.

• The earliest precursors, such as pronormoblasts and erythroblasts, are relatively large cells with nuclei.

• As these cells mature, they reduce in size, condense their nuclei, and eventually extrude the nucleus entirely.

• The final mature red blood cell is a small, biconcave, anucleate cell with an average diameter of about 6-8 micrometers, designed for flexible passage through tiny capillaries and efficient gas exchange.

Therefore, mature RBCs are smaller than their earlier nucleated precursors.

Statement (2): Role of Platelets in Blood Clotting

Platelets are small, anucleate cell fragments derived from megakaryocytes, and they play a crucial role in blood clotting (hemostasis).

• When a blood vessel is damaged, platelets quickly adhere to the injured site, aggregate to form a platelet plug, and release chemicals that activate the coagulation cascade.

• Thus, statement (2) that platelets play an important role in blood clotting is correct.

Statement (3): Neutrophils as Major Phagocytic Cells

Neutrophils are the most abundant type of white blood cells and are indeed the major phagocytic cells of the immune system.

• They engulf and destroy invading pathogens through phagocytosis and are key players in the innate immune response.

• Therefore, statement (3) is accurate.

Statement (4): Basophils Being Present in Least Amount

Among white blood cells, basophils are the least abundant in peripheral blood, typically constituting less than 1% of circulating leukocytes.

• Basophils release histamine and other mediators involved in allergic and inflammatory responses.

• Statement (4) is thus correct.

Summary Table of Blood Cell Features

Conclusion

Among the provided statements about blood, the only incorrect one is the claim that mature RBCs are larger than their precursor cells. In reality, mature red blood cells decrease in size during differentiation. Platelets, neutrophils, and basophils’ described roles and relative abundance are accurate, reflecting their critical functions in clotting, immunity, and inflammation respectively.

Correct answer: (1) Mature RBC is of larger size as compared to its precursor cells.