Match List-I with List-II.
| List-I | List-II |
|---|---|
| A. Aneuploidy | I. Absence of one of the X chromosomes |
| B. Polyploidy | II. Gain or loss of a chromosome |
| C. Turner’s syndrome | III. Increase in a whole set of chromosomes |
| D. Klinefelter’s syndrome | IV. Presence of an additional copy of X chromosome |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A-II, B-III, C-I, D-IV
Chromosomal disorders are caused by the absence, excess or abnormal arrangement of chromosomes. Aneuploidy and polyploidy are the two ways the number changes; Turner’s and Klinefelter’s syndromes are disorders of the sex chromosomes.
(A) Aneuploidy — this matches (II) Gain or loss of a chromosome. It results from failure of segregation of chromatids during cell division.
(B) Polyploidy — this matches (III) Increase in a whole set of chromosomes. It results from failure of cytokinesis after telophase.
(C) Turner’s syndrome — this matches (I) Absence of one of the X chromosomes, i.e., 45 with X0. Such females are sterile.
(D) Klinefelter’s syndrome — this matches (IV) Presence of an additional copy of X chromosome, giving the karyotype 47, XXY.
So the correct code is A-II, B-III, C-I, D-IV.
NCERT Extract:
Chromosomal Disorders – “… Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy. … Failure of cytokinesis after telophase stage of cell division results in an increase in a whole set of chromosomes in an organism and, this phenomenon is known as polyploidy.”
Chromosomal Disorders – “… 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. … Turner’s Syndrome : Such a disorder is caused due to the absence of one of the X chromosomes, i.e., 45 with X0, Such females are sterile as ovaries are rudimentary besides other features including lack of other secondary sexual characters (Figure 4.17 b).”
Figure 4.17 Diagrammatic representation of genetic disorders due to sex chromosome composition in humans : (a) Klinefelter Syndrome; (b) Turner’s Syndrome