Match List-I with List-II.
| List-I | List-II |
|---|---|
| A. Turner’s syndrome | I. Trisomy |
| B. Linkage | II. 45 with X0 |
| C. Phenylketonuria | III. Morgan |
| D. Down’s syndrome | IV. Inborn error of metabolism |
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-IV, D-I
The four items come from different parts of the chapter: two chromosomal disorders, one Mendelian disorder and one of Morgan’s findings.
(A) Turner’s syndrome — this matches (II) 45 with X0. One of the X chromosomes is absent.
(B) Linkage — this matches (III) Morgan. Morgan coined the term linkage for the physical association of genes on a chromosome.
(C) Phenylketonuria — this matches (IV) Inborn error of metabolism. The enzyme that converts phenylalanine into tyrosine is lacking.
(D) Down’s syndrome — this matches (I) Trisomy. There is an additional copy of chromosome 21.
So the correct code is A-II, B-III, C-IV, D-I.
NCERT Extract:
Linkage and Recombination – “… Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage to describe this physical association of genes on a chromosome and the term recombination to describe the generation of non-parental gene combinations (Figure 4.11).”
Mendelian Disorders – “… Phenylketonuria : This inborn error of metabolism is also inherited as the autosomal recessive trait.”
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). … 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).”