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KCET · BIOLOGY · STD 12 - 4. Principles of Inheritance and Variation

Choose the possible genotype responsible for lightest skin colour in human beings.

  1. A AABBCC
  2. B AaBbCc
  3. C aabbcc
  4. D AABbCc
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Answer & Solution

Correct Answer

(C) aabbcc

Step-by-step Solution

Detailed explanation

(C) aabbcc,
Three genes (six alleles) contribute to skin colour. The three genes are A, B, and C and their alleles are A and a, B and b, and C and c, where A, B and C contribute to dark skin colour and a, b and c contribute to light skin colour. For human skin colour, the alleles code for the production of the skin pigment melanin, and their effect is cumulative. This implies that a person with genotype AABBCC has six alleles that code for high production of melanin, and their effect is cumulative. This implies that a person with genotype AABBCC has six allels that code for high production of melanin, thus indicating that their skin would be very dark. On the other hand, a person with genotype aabbcc has six alleles that code for low production of melanin and thus their skin would be very light.