1. What is bone marrow?
  2. Why is bone marrow important?
  3. What do red blood cells (RBC) do?
  4. Why do red blood cells have red colour?
  5. What is anemia?
  6. What is Thalassaemia?
  7. How does a person get thalassaemia?
  8. Treatment Of Thalassaemia
  9. What is Sickle cell anaemia?
  10. What do white blood cells (WBC) do?
  11. What is leukemia (blood cancer)?
  12. What is platelet?
  13. What is Hemophilia?
  • In CSAT 2011, we saw a (but static) question from blood groups.
  • Although It is not necessary that UPSC will again ask something from blood-topic again, but a serious player should be well versed in such “Static/Theory” parts of science.
  • Static Question: means, it is given in the books/manuals (or indirectly related). Such question doesn’t have current-affairs and can be solved easily if your basic concepts are clear.

What is bone marrow?
it is a soft, pulpy tissue that fills the cavities of bones.
Why is bone marrow important?
Because It produces all of the body’s blood cells—red blood cells (RBC), white blood cells (WBC), and platelets.
What do red blood cells (RBC) do?
They transfer oxygen from the lungs to the cells.

(technically correct):


  • It is not red blood cell, but red blood corples (RBC). because cells have nucleus, RBC doesn’t have nucleus so it is not a cell and hence they die after 120 days. (or atleast that’s what the Anatomy professor had told me.). but to keep the matter simple, I shall refer It as RBC/ Red blood cell.


Why do red blood cells have red colour?

  • Because they contain haemoglobin.
  • Haemoglobin contains iron,
  • that’s why red colour.

RBC looks like this

Photo by Dr. Tony Brain/Science Source/Photo Researchers, Inc.

What is anemia?

  • When your blood has less hemoglobin (=Hence Less RBC)
  • so, less oxygen is transferred from your lungs to your cells.
  • That’s why less energy is produced, and you get tired very easily. That is anemia. Majority of girls in India, suffer from Anemia because of malnutrition.

What is Thalassaemia?

  • When you bone marrow produces defective type of red blood cells, you have thalassaemia.
  • It means your own blood cannot carry oxygen from lungs to the cells so you need to have a healthy person’s blood in your body.
  • And since red blood cells have a lifespan of only 120 days, you require regular blood transfusion from a normal person.
  • Thalassaemia is a genetic disorder. (=heriditary disease)
  • means it is transferred from one generation to another.
  • Mind it: thalassaemia is not a contagious disease. (means you cannot get it by infection, like in common cold, swine flu or chickenpox.)
  • It is important to learn the mechanism of thalassaemia for CSAT prelims point of view (WFST questions). Because it is an example of “Mendel’s experiment on peas” given in the NCERTs.
  • Anyways,  I’ll try to simplify by getting not so technically correct.”

How does a person get thalassaemia?

  • Suppose a person has recessive (=bad) gene that causes thalassaemia. But he himself doesn’t show the symptoms of thalassaemia, he appears totally normal. So we’ll call this guy a “carrier”.or Thalassaemia Minor. E.g. Amitabh Bacchan and Amisha Patel. About 6% of Indian Juntaa is Thalassaemia Minor.
  • Now Another lady is completely healthy and doesn’t have any bad genes. We call her “non-carrier”.
  • When Carrier marries with non-carrier, the baby thus produced will be either normal or carrier. (50-50% change) but there is 100% guarantee that the baby will not have thalassaemia disease.
  • But, if two Carriers marry, there is 25% chance that their baby will be suffering from thalassaemia. See the photo for chart, to get the idea.

carrier chart.

Image by Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation.

  • For this reason, prospective brides and grooms should not only check the ‘kundli’ (horoscope), but also their blood reports. Just think about future of your baby, the expensive medicines and inconvinient blood transfusion for the rest of his/her life.

Treatment Of Thalassaemia

  • as we saw, defective bone marrow produces defective red blood cells and so thalassaemia occurs.
  • So to fix thalassaemia permanently, we have to get fresh and healthy bone-marrow from a donor and transplant it in the patient. = Bone marrow transplant.
  • Problem: hard to find compatible donors and it is very expensive.

What is Sickle cell anaemia?

    • Normal and healthy red blood cells look like a round/oval/coin shaped drug tablet, like in this photo.

sickle cell

  • But if a person has defective genes, his bone marrow will produce RBC with sickle shape (that agricultural tool)  like in this photo.
  • Because of this abnormal shape, such sickle RBC cannot flow freely in the tiny blood vessels = less oxygen supply.
  • Sickle cell anaemia, has the same genetic mechanism/Mendel’s law explained in thalassaemia case.

Interval WFST

which of the following statements are true?

  • Thalassaemia is a contagious disease.
  • if a person with recessive genes for thalassaemia, marries with normal person, there is 50% chance that the baby will have thalassaemia disease.
  • Sickle cell anemia is not a hereditary disease.
  • In normal Anaemia, healthy diet improves the blood quality but in Thalassaemia/ Sickle Cell Anaemia, diet will not bring improvement in Blood quality

Enough talk about RBC, let’s move to second type of blood cells called white blood cells (WBC)

What do white blood cells (WBC) do?


  • They are the policemen of our body.
  • They defend our body by attacking virus, bacteria and other antigens. (=badguys): no FIR, No Chargesheet, No court case, Direct encounter.
  • But here is a problem: during organ transplant (kidney, liver, etc), these WBC also consider the forieng Kidney as badguy and attack it. so patient is given variety of immunosuppressant drugs.
  • It is the same reason why doctors insist on organs from siblings and relatives. Because then WBC will not be very angry with them!

What is leukemia (blood cancer)?

  • WBC / white blood cells are also known as leucocytes.
  • When your blood has abnormally high number of WBC, you have leukemia, also known as blood cancer.

What is platelet?

  • When your body gets injured, after some time blood stops flowing from the wound.
  • Because of this platelets, blood gets clotted.
  • So, they are also good guys, otherwise , even in the smallest injury. Your bleeding will not stop and you will die.
  • Platelets are also known as thrombocytes.

What is Hemophilia?

It is another hereditary blood disease characterized by the inability of blood to clot.
means if you get wounded, the bleeding will not stop.
Mechanism is similar to Thalassaemia / Mendel’s law of heredity.
Which of the following statements are correct?

  1. In Hemophilia bone marrow produces defective type of red blood cells (RBC).
  2. In Thalassemia, blood clotting does not occur.
  3. Hemophilia doesn’t follow Mendel’s law on heredity.
  4. Vitamin E is helps in Blood clotting and is soluble in water