Match List - I with List - II.

Choose the correct answer from the options given below:

(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

The correct answer is Option (3) -(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

The total number of chromosomes in a normal human cell is 46 (23 pairs). Out of these 22 pairs are autosomes and one pair of chromosomes are sex chromosome. Sometimes, though rarely, either an additional copy of a chromosome may be included in an individual or an ndividual may lack one of any one pair of chromosomes. These situations are known as trisomy or monosomy of a chromosome, respectively. Such a situation leads to very serious consequences in the individual.

Down’s syndrome, Turner’s syndrome, Klinefelter’s syndrome are common examples of chromosomal disorders.

Down’s Syndrome : The cause of this genetic disorder is the presence of an additional copy of the chromosome number 21 (trisomy of 21). This disorder was first described by Langdon Down (1866). The affected individual is short statured with small round head, furrowed tongue and partially open mouth. Palm is broad with characteristic palm crease. Physical, psychomotor and mental development is retarded.

Klinefelter’s Syndrome : This genetic disorder is also caused due to the presence of an additional copy of X- chromosome resulting into a karyotype of 47, XXY. Such an individual has overall masculine development, however, the feminine development (development of breast, i.e., Gynaecomastia) is also expressed. Such individuals are sterile.

Turner’s Syndrome : Such a disorder is caused due to the absence of one of the X chromosomes, i.e., 45 with XO, Such females are sterile as ovaries are rudimentary besides other features including lack of other secondary sexual characters.