Question

In a matured RBC, nucleus is present in
A. Frog
B. Rabbit
C. Both A and B
D. None of the above

Answer 1

Hint: 1.In mammals, the red blood cells lack nucleus.
2.Red blood cells have a nucleus in other vertebrates

Complete answer:
Option A: Frogs are vertebrates that belong to the class amphibia. Amphibians have nucleated red blood cells. Their nucleus contains regular genetic material that is DNA as every other cell. Therefore this is the correct answer.

Erythropoiesis is the process of the formation of red blood cells or erythrocytes from the erythropoietic stem cells. Stem cells are nucleated cells and in all vertebrates other than mammals, they develop and mature to form nucleated red blood cells.
Option B: Rabbits are vertebrates and they belong to class Mammalia. Since mammals have mature red blood cells that lack a nucleus, rabbit red blood cells lack a nucleus. In mammals, the precursor of red blood cells is nucleated. These un mature nucleated red blood cells are seen in the bone marrow of adults and in the blood of fetuses and newborns. During the process of maturation, they lose their nucleus. Lack of nucleus facilitates them to provide maximum space to the hemoglobin which is the carrier of gas molecules. Therefore, this is the incorrect option.
Option C: Rabbits do not have mature red blood cells with nucleus. Therefore, this is the incorrect option.
Option D: Frogs have nuclei present in their matured red blood cells. Therefore, this is the incorrect option.

Hence, the correct answer is option (A)

Note: In adult mammals, the presence of nucleated red blood cells in the bloodstream indicates the premature release of red blood cells from bone marrow to the bloodstream. This indicates a deficiency in mature RBCs and results in conditions like anemia, thalassemia, etc