Question

Mark the incorrect one regarding human erythrocytes

• A. Erythropoesis occurs in the red bone marrow in the adult
• B. RBCs are the most abundant formed elements in the blood
• C. After 120 days of life span they are destroyed in spleen
• D. RBCs are devoid of nucleus in some of the mammals

Answer 1

Answer: (D)

RBCs are devoid of nucleus in some of the mammals

Answer 2

The question asks to identify the incorrect statement regarding human erythrocytes. Let's analyze each option:

1. Erythropoiesis occurs in the red bone marrow in the adult: This statement is correct. In adult humans, red blood cells (erythrocytes) are produced in the red bone marrow.

2. RBCs are the most abundant formed elements in the blood: This statement is correct. Red blood cells are indeed the most numerous formed elements (cells and cell fragments) in human blood, typically accounting for about 40-45% of the total blood volume.

3. After 120 days of life span they are destroyed in spleen: This statement is correct. Human red blood cells have an average lifespan of approximately 120 days, after which old and damaged RBCs are primarily filtered out and destroyed in the spleen, which is why the spleen is often called the "graveyard of RBCs."

4. RBCs are devoid of nucleus in some of the mammals: This statement is technically correct but can be considered misleading in the context of a characteristic feature.

   • Mature human erythrocytes are indeed devoid of a nucleus. This is a crucial adaptation for maximizing hemoglobin content and enabling efficient oxygen transport.
   • This anucleated state is a characteristic feature of most mammalian erythrocytes. While there are exceptions (e.g., camelids like camels and llamas have nucleated, oval RBCs), the general rule for mammals is that their mature RBCs lack a nucleus.
   • The phrasing "in some of the mammals" is factually true (since humans are mammals and their RBCs are anucleated, and there are other mammals whose RBCs are also anucleated). However, it might be considered incorrect in the context of a defining characteristic because anucleation is a feature of the vast majority of mammals, not just "some" in a limited sense. If "some" implies a small, non-representative subset, then it would be misleading. Given that options 1, 2, and 3 are unequivocally correct and fundamental facts about human erythrocytes, option 4 is the most likely candidate for the "incorrect" statement due to its imprecise generalization, potentially understating the prevalence of anucleated RBCs among mammals. It's a defining feature of mammalian RBCs.

Therefore, while factually true that humans are among "some mammals" with anucleated RBCs, the statement is often considered imprecise or misleading in biological contexts where anucleation is presented as a general characteristic of mammalian erythrocytes. Compared to the other three options which are perfectly accurate, this statement is the least precise.