Question

Which of the following cells are round and biconcave in shape?
A. White blood cells
B. Red blood cells
C. Columnar epithelial cells
D. Nerve cells

Answer 1

There are three kinds of cells in the blood: RBC, WBC, and platelets. These are the cellular components of blood, millions of which in the circulation of vertebrates give the blood its characteristic colour, and the average life of humans is 100-120 days.

Complete answer: The red-coloured, iron-containing pigment called haemoglobin is found in red blood cells, also known as erythrocytes. Red blood cells or erythrocytes are widely called blood cells and are a means by which oxygen is provided by our circulatory system into human body tissue. The oxygen in the lungs is obtained by a red blood cell and precedes it through the capillaries to the blood tissues. A very rich source of haemoglobin is RBCs. Because of the wide field, red blood cells have a biconcave shape that allows the cell to exchange oxygen. In the bone marrow, red blood cells produce mainly red blood cells in a circular form, but some of them are oval. An erythrocyte is a cell that contains significant quantities of haemoglobin and is specialized for the transport of oxygen. Erythrocytes are round in mammals and biconcave in form. They are devoid of nuclei and other organelles connected to membranes. By glycolysis, they extract energy and act as tiny haemoglobin packets.
Hence, the right answer is B-Red blood cells.

Note: The red blood cell in the bone marrow develops in several stages: it becomes a haemocytoblast erythroblast, a multipotential cell in the mesenchyme; over two to five days of growth, the erythroblast gradually fills with haemoglobin, and its nucleus and mitochondria (particles in the cytoplasm that provide the cell with energy) vanish.