Target Exam

CUET

Subject

Biology

Chapter

Principles of Inheritance and Variation

Question:

Match List-I with List-II

List-I Genetic disorder

List-II Characteristics

(A) Haemophilia

(I) Mutation in HBB gene

(B) Thalessemia

(II) Sex-linked recessive disease

(C) Phenylketonuria

(III) Aneuploidy

(D) Klinefelter's syndrome

(IV) Mental retardation and reduced hair and skin pigmentation

Choose the correct answer from the options given below:

Options:

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

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

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

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

Correct Answer:

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

Explanation:

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

List-I Genetic disorder

List-II Characteristics

(A) Haemophilia

(II) Sex-linked recessive disease

(B) Thalessemia

(I) Mutation in HBB gene

(C) Phenylketonuria

(IV) Mental retardation and reduced hair and skin pigmentation

(D) Klinefelter's syndrome

(III) Aneuploidy

A. Haemophilia is a sex linked recessive disease, which shows its transmission from unaffected carrier female to some of the male progeny has been widely studied. 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.

B. Thalassemia is an autosome-linked recessive blood disease transmitted from parents to the offspring when both the partners are unaffected carrier for the gene (or heterozygous). 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.α Thalassemia is controlled by two closely linked genes  andHBA1 and HBA2 on chromosome 16 of each  parent .While β Thalassemia is controlled by a single gene HBB on chromosome 11 of each parent and occurs due to mutation of one or both the genes.

C. Phenylketonuria, which occurs in humans. The disease is caused by mutation in the gene that codes for the enzyme phenyl alanine hydroxylase (single gene mutation). This manifests itself through phenotypic expression characterised by mental retardation and a reduction in hair and skin pigmentation.     

D. Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy. For example, Down’s syndrome results in the gain of extra copy of chromosome 21. Similarly, Turner’s syndrome results due to loss of an X chromosome in human females. Klinefelter’s Syndrome is also caused due to the presence of an additional copy of X- chromosome resulting into a karyotype of 47, 44+XXY