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Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYPrinciples of Inheritance and Variation1 Mark
MCQ
Human skin colour is an example of:
  • A
    Intragenic interaction
  • B
    Interallelic interaction
  • C
    Quantitative inheritance
  • D
    Pleiotropy
✓

Answer

  1. Quantitative inheritance

Explanation:

Inheritance of human skin colour is an example of polygenic inheritance. This character is determined by two or more pairs of genes and they have an additive effect. These genes are known as cumulative genes.

Here, more number of dominant alleles results in more expression of that character. Assume that three "dominant" capital letter genes (A, B and C) control dark pigmentation because more melanin is produced. The "recessive" alleles of these three genes (a, b & c) control light pigmentation because lower amounts of melanin are produced. Each "dominant" capital gene produces one unit of colour so that a wide range of intermediate skin colours are produced, depending on the number of "dominant" capital genes in the genotype.

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