Question

Which of the following animals have nuclei in their mature red blood corpuscles ?
A. Cow
B. Horse
C. Elephant
D. None of the above

Answer 1

Hint: Simple organisms like sponges and Coelenterates circulate water from their surroundings through their body cavity to facilitate the cells to exchange those substances which are harmful or waste substances produced by the body. More complex organisms use special fluids within their bodies to transport such material.

Complete Answer:
- Blood is the most commonly used body fluid by most of the higher organisms including humans for this purpose. Blood is a special connective tissue consisting of a fluid Matrix plasma and formed elements.
- Red blood cells, White blood cells and platelets are called formed elements in the blood. And they constitute nearly 45% of the blood.
- Red blood cells are the most abundant of all the cells in the blood. RBC have an average lifespan of 120 days after which they are destroyed in the spleen which is also known as the graveyard of RBC.
- Red blood cells are devoid of nucleus that means nucleus is absent in most of the mammals and biconcave in shape
- Nucleus is absent in red blood cells to provide more space for Haemoglobin. Haemoglobin is a red coloured iron containing complex protein according to which the name and the colour of the cells are.
- Mammals include horse, elephant, dog, human etc. In which the nucleus is absent in red blood cells.

So the correct answer is (D).

Note: A healthy individual has on an average 5 millions to 5.5 millions of red blood cells per millimetre cube of blood. RBC are formed in the red bone marrow in adults.