Question

Which among the following is not found in the red blood corpuscles of human beings?
A. Haemoglobin
B. Plasmalemma
C. Nucleus
D. Cytoplasm

Answer 1

Hint: Red blood cells, also known as red cells, red blood corpuscles, haematids, erythroid cells or erythrocytes, or RBC is the most common type of blood cell.

Complete answer: RBC is the principal means of delivering oxygen to the body tissues—via blood flow through the circulatory system.
1. Red cells contain a special protein called haemoglobin. It helps to carry oxygen from the lungs to the rest of the body and then returns carbon dioxide from the body to the lungs so it can be exhaled.
2. Blood appears red because of the large number of red blood cells, which get their color from the hemoglobin as the “haem” part of the haemoglobin consists of iron.
4. As mature red blood cells contain no nucleus, protein biosynthesis is assumed to be absent in these cells because of the lack of nuclei and organelles, mature red blood cells do not contain DNA and cannot synthesize any RNA, and consequently cannot divide and have limited repair capabilities.
5. The cytoplasm is present in red blood cells to contain the organelles and is the location where most cell activities occur.

So, the answer is C. Nucleus

Note: The main components of blood are- plasma, red blood cells, white blood cells, and platelets. The nucleus is not present in mature RBC of humans which leaves space for haemoglobin to carry oxygen. In mammals, the expulsion of the nucleus from erythroblasts leads to the formation of reticulocytes.
In order to produce mature biconcave red blood cells, organelles and ribosomes are selectively eliminated from reticulocytes as well as the plasma membrane undergoes remodeling.