Read the given passage and answer the question given below.
The 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. The heterozygous female (carrier) for the disease may transmit it to sons. The possibility of a female becoming a sufferer of disease is extremely rare because mother of such a female has to be at least carrier and the father should be sufferer. The family pedigree of Queen Victoria shows a number of suffering descendents as she was a carrier of the disease.
Identify the genotype of queen Victoria. (* - gene for disorder)
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → x*x
Queen Victoria was a carrier: a woman with one X carrying the gene for the disorder and one normal X.
Option (1) x*x* — Incorrect. X*X* would make her a sufferer, not a carrier.
Option (2) x*x — Correct. Queen Victoria was not affected but passed haemophilia to some of her descendants, so she was a carrier. A carrier female is heterozygous, with one X bearing the gene for the disorder: X*X.
Option (3) X*Y — Incorrect. X*Y is an affected male.
Option (4) XX — Incorrect. XX is a normal female with no gene for the disorder.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.