Which one of the following options will express intermediate skin colour in an individual?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → AaBbCc
Human skin colour is a polygenic trait. In the book’s model three genes A, B and C control it. Each dominant allele adds the same amount of darkness, so the colour depends on how many dominant alleles a person carries, out of six.
Option (1) AABBCC — Incorrect. Six dominant alleles give the darkest skin colour.
Option (2) aabbcc — Incorrect. No dominant allele gives the lightest skin colour.
Option (3) AaBbCc — Correct. It has three dominant and three recessive alleles, the midpoint between the two extremes.
Option (4) aaBbcc — Incorrect. It has only one dominant allele, so the skin would be light, close to aabbcc.
NCERT Extract:
Polygenic Inheritance –
