Select the mendelian disorders from the following:
A. Thalassemia
B. Turner's Syndrome
C. Cystic Fibrosis
D. Sickle cell anaemia
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → A, C and D only
A Mendelian disorder is caused by a change (mutation) in a single gene and is inherited by Mendel's principles. A chromosomal disorder is caused by an extra, missing or wrongly placed chromosome.
A. Thalassemia — Correct. An autosomal recessive blood disease caused by mutation or deletion of the genes for globin chains.
B. Turner's Syndrome — Incorrect. It is a chromosomal disorder: one X chromosome is missing (44 + X0).
C. Cystic Fibrosis — Correct. A single-gene disorder, listed by NCERT among the common Mendelian disorders.
D. Sickle cell anaemia — Correct. An autosomal recessive disorder caused by one base change in the gene for the β-globin chain.
NCERT Extract:
Mendelian Disorders – “Broadly, genetic disorders may be grouped into two categories – Mendelian disorders and Chromosomal disorders. Mendelian disorders are mainly determined by alteration or mutation in the single gene. These disorders are transmitted to the offspring on the same lines as we have studied in the principle of inheritance. The pattern of inheritance of such Mendelian disorders can be traced in a family by the pedigree analysis. Most common and prevalent Mendelian disorders are Haemophilia, Cystic fibrosis, Sickle-cell anaemia, Colour blindness, Phenylketonuria, Thalassemia, etc.”