Match List-I with List-II.
| List-I (Disorder) | List-II (Cause) |
| A. Colour blindness | I. Reduced rate of synthesis of one of the globin chains of haemoglobin |
| B. Haemophilia | II. Substitution of glutamic acid by valine at the sixth position of the β-globin chain |
| C. Sickle-cell anaemia | III. Defect in either red or green cone of the eye |
| D. Thalassemia | IV. A protein of the cascade involved in the clotting of blood is affected |
Choose the correct answer from the options given below.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A-III, B-IV, C-II, D-I
(A) Colour blindness — this matches (III) Defect in either red or green cone of the eye. It is a sex-linked recessive disorder. Because of the faulty cone, the person cannot tell red from green.
(B) Haemophilia — this matches (IV) A protein of the cascade involved in the clotting of blood is affected. Blood clots through a chain (cascade) of proteins. When one protein of this chain is faulty, a simple cut can lead to non-stop bleeding.
(C) Sickle-cell anaemia — this matches (II) Substitution of glutamic acid by valine at the sixth position of the β-globin chain. A single base change (GAG to GUG) in the beta globin gene causes this change. The faulty haemoglobin polymerises under low oxygen and the RBCs become sickle-shaped.
(D) Thalassemia — this matches (I) Reduced rate of synthesis of one of the globin chains of haemoglobin. A mutation or deletion lowers the making of the α or β chain. The quantity of a chain falls, whereas in sickle-cell anaemia the quality of the chain is changed.
NCERT Extract:
Mendelian Disorders – “… Colour Blidness : It is a sex-linked recessive disorder due to defect in either red or green cone of eye resulting in failure to discriminate between red and green colour.”
Mendelian Disorders – “… In this disease, a single protein that is a part of the cascade of proteins involved in the clotting of blood is affected. Due to this, in an affected individual a simple cut will result in non-stop bleeding.”
Mendelian Disorders – “… The defect is caused by the substitution of Glutamic acid (Glu) by Valine (Val) at the sixth position of the beta globin chain of the haemoglobin molecule.”
Mendelian Disorders – “… The defect could be due to either mutation or deletion which ultimately results in reduced rate of synthesis of one of the globin chains (α and β chains) that make up haemoglobin.”