Question

Study the pedigree chart of a certain family given above and select the correct conclusion which can be drawn for the character. 
  

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

Answer 1

Hint: A pedigree is a graph of a family's ancestral heritage over many centuries. As triangles, males are represented, while females are represented as circles. Shaded symbols indicate that a disease affects a person, while an unshaded symbol indicates that they are unaffected.

Complete answer:
All parents should have at least one clone of the allele and have both sons and daughters exhibiting the trait. Female parents are seen average in the given pedigree, which makes their heterozygous carrier. As it is not expressed in a heterozygous female parent, the condition is recessive. The male parent, since the allele is recessive, is homozygous recessive.

Daughters receive one X chromosome from the father and another from the mother; it would be common for daughters to receive a normal X chromosome from the carrier female parent and an affected X chromosome from an affected male parent. The disorder is recessive X-linked and may be color-blindness, and is also a recessive X-linked trait.

Hence, the correct answer is option (B)

Note: Types of Colour Blindness:
1)The most frequent form of red-green blindness of colour is Deuteranomaly. This makes the green seem redder.
2)The red presentation of Protanomaly is greener and less vivid.
3)Both protanopia and deuteranopia cause you to be unable to say the difference at all between red and green.