Tag: keeping diseases away
Questions Related to keeping diseases away
Select the correct match.
Haemophilia is a?
A daughter will not normally be colourblind, unless her mother is ...... and her father is ....
Daughters inherit x chromosomes of father & mother respectively since one x chromosome masks the effect of another x chromosome, a daughter will only be colourblind if her mother is a carrier & father is colorblind.
Select the incorrect statement from the following :
If both parents are bald and their first female child is normal, then the chances of baldness in their second male child is?
The most common type of haemophilia is due to congenital absence of
The possibility of a female becoming haemophilic is extremely rare because the mother of such a female has to be at least (i) and father should be (ii).
- Haemophilia is genetically due to the presence of a $recessive$ sex-linked gene h, carried by the X chromosome.
- A female becomes haemophilic only when both Its X chromosomes carry the gene $(XhXh)$. However, such females (mothers) generally die before birth because the combination of these two recessive alleles is lethal. A female having only one allele for haemophilia $(XX^h)$ appears normal because of the allele for normal blood clotting present on the other X-chromosome is dominant. Such females are known as carriers.
- In the case of males, a single gene for the defect is able to express itself as the Y-chromosome is devoid of any corresponding allele $(Xh^Y)$.
- Thus, the possibility of a human female becoming haemophilic is extremely rare because she has to be homozygous recessive for the trait, i.e., her father must be a haemophilic and mother must be at least a carrier.
Which one of the following is a genetically transmitted character?
Correct pathway for synthesis of skin pigment is?