Name the blood cells in which nucleus is absent

1. Analyze the question You are asked which of the listed blood components has no nucleus.

2. Explain the concept Blood contains these main components:

• Red blood cells (erythrocytes): mature mammalian RBCs have no nucleus.
• White blood cells (leucocytes): all have a nucleus. They are divided into: • Granulocytes: neutrophils, eosinophils, basophils (lobed nuclei). • Agranulocytes: lymphocytes and monocytes (single, rounded or kidney-shaped nucleus).
• Platelets (thrombocytes): these are not complete cells. They are small fragments of cytoplasm broken off from large bone marrow cells called megakaryocytes, so they have no nucleus.

3. Solution

• A. Lymphocytes: white blood cells with a large, round nucleus. Nucleus present.
• B. Blood platelets: cell fragments with no nucleus. Nucleus absent.
• C. Monocytes: white blood cells with a kidney-shaped nucleus. Nucleus present.
• D. Eosinophil: a granulocyte with a bi-lobed nucleus. Nucleus present.

4. Answer The correct option is B. Blood Platelets.

Note: Red blood cells would also be correct if they were listed, but they are not among the options here.

5. Exam tip Remember "No nucleus: RBCs and platelets." Every white blood cell has a nucleus. Platelets help in blood clotting, and they are fragments, not true cells.