Question

Study the pedigree chart of certain families given here and select the correct conclusion.

A. The female parent is heterozygous
B. The parent could not have had a normal daughter for this character.
C. The trait under study could not be colour blindness
D. The male parent is homozygous dominant.

Answer 1

Hint: Pedigree chart is pictorial representation of how alleles or traits are inherited from parent to offsprings. This chart is present in the creative of the presence and the absence or the affected genes to give a clear understanding in the study.

Complete answer:
In the pedigree the parents are heterozygous in which one parent show diseased allele
In the below part of pedigree we can see two daughter offsprings and two male offsprings in which both female are affected with diseased allele and in males one of the male is affected whereas the other male is not affected
Hence, it is an x linked disease because both the daughters’ are affected as daughters have both XX genes.
-The female is heterozygous this is the correct answer for the above explanation and the above pedigree. Option A is correct
-The parent could not have had a normal daughter for this character. Option B is not correct because the male x is affected as the female offsprings receive
-XX genes from the parents cannot be a normal daughter for this character. The trait under study could not be colour blindness. Option c is not correct, because there is a possibility the affected gene from the parents could be colour blinded.
-The male parent is homozygous dominant : The male parent is with XY chromosomes it is the x allele which got affected hence all the female offspring were affected which makes the allele heterozygous dominant. So option D is not correct.

Hence, the correct answer is option (A).

Note: This chart helps in clear understanding of the transmission of certain character from parental to offsprings of the family record. It helps in understanding the pattern of inheritance in the entire generation in case of any genetic disorders