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Question
Explain the inheritance of sex-linked characters in human being.
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Solution
Haemophilia is commonly known as bleeder’s disease, which is more common in men than women. This hereditary disease was first reported by John Cotto in 1803. Haemophilia is caused by a recessive X-linked gene. A person with a recessive gene for haemophilia lacks a normal clotting substance (thromboplastin) in blood, hence minor injuries cause continuous bleeding, leading to death. The females are carriers of the disease and would transmit the disease to 50% of their sons even if the male parent is normal. Haemophilia follows the characteristic criss - cross pattern of inheritaitce.
RELATED QUESTIONS
In a certain species of animals, black fur (B) is dominant over brown fur (b) Show the possible ratio of genotypes and phenotypes of the offspring of the pure breeding different coloured parents.
A family consists of two parents and their five children and the pedigree chart shown below shows the inheritance of the trait colour blindness in them.
On which chromosome is the gene of this trait located?
Give Technical Term:
Name a genetic disease in which a person cannot distinguish red and green colour.
Mention, if the following statement is True or False. If false rewrite the wrong statement in its correct form:
Colour blindness is a Y-linked character.
Mention, if the following statement is True or False. If false rewrite the wrong statement in its correct form:
A colourblind male cannot distinguish any colour.
Short Answer Question.
Observe the given pedigree chart and answer the following question.
Give an example of a trait in human beings which shows such a pattern of inheritance.
Haemophilia is more common in males because it is a ____________.
What would be the progeny obtained if a woman carrier for colour blindness marries a normal vision man?
Give examples of X-linked traits.
Holandric genes are located ______.
