Question

Select the chromosomal disorders from the following diseases affecting humans
I. Haemophilia
II. Down's syndrome
III. Klinefelter's syndrome
IV. Sickle cell anemia
V. Turner's syndrome
VI. Thalessemia

• A. All except II, III and V
• B. All except I and IV
• C. All except I, IV and VI
• D. All except I, II and VI

Answer 1

Answer: (C)

Chromosomal disorders are the diseases/conditions occur due to change in the number of the chromosomes in the individual. Down's syndrome is due to extra 21st chromosome, Turner's syndrome is caused in female due to lack of one of the X chromosome from the 23rd pair of XX. Klinefelter's syndrome is caused due to extra copy of the X chromosome in a male making the 23rd pair as XXY. Haemophilia, sickle cell anemia, thalassemia are disorders occurring due to change in a single gene of the chromosome rather than the whole chromosome undergoing change. These are also called as Mendelian disorders as they generally follow Mendel's laws of inheritance.