Question

The shape of red blood cells is
A. Disc
B. Amoeboid
C. Cuboid
D. Spherical

Answer 1

Hint: Red blood cells are also called erythrocytes. They are biconcave shaped formed elements of the blood.

Complete answer:
To answer this question, we should know about the formed elements of the blood.
Let’s discuss the blood as tissue and then move to the red blood cells.
Blood is one of the components of the cardiovascular system. It is a tissue with liquid plasma and three main types of formed elements.
Formed elements refer to the cells present in the blood plasma. There are three types of cells present in the blood: red blood cells, white blood cells, and platelets.
Red blood cells (RBCs) are responsible for the red color of the blood. These cells are rich in the protein hemoglobin that turn bright red when it binds to the oxygen. Here, we can also deduce that the function of the delivery of oxygen to different body cells is performed by RBCs only.
Let’s talk about the different shapes given now. Ameboid shape refers to the irregular shape like that of the Amoeba. However, RBCs have a definite shape. The amoeboid shape is the feature of white blood cells. Cuboid and spherical shapes can be represented by a Rubik's cube and a football respectively.
Let’s talk about the shape of the RBCs now. RBCs have a diameter of 7-8 micrometers and are biconcave shaped structures. Now, let’s recall the shape of the concave lens here. These lenses are broader at the ends and narrow in the middle. If we put two concave lenses one over the other, the shape obtained is that of the RBCs.
Since this shape resembles a disc, RBCs are also said to be disc-shaped cells.

So, the correct answer is option A. Disc.

Note:
 One should know that RBCs do not have nuclei. Therefore, these cells do not divide and have a definite lifespan. Another peculiar feature of RBCs is the absence of mitochondria which is why they respire anaerobically.