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STD 12 - 4. principal of inheritance and variation — BIOLOGY STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 ScienceBIOLOGYSTD 12 - 4. principal of inheritance and variation1 Mark
MCQ
Inheritance of skin colour in humans is an example of
  • A
    point mutation
  • ✓
    polygenic inheritance
  • C
    codominance
  • D
    chromosomal aberration.
✓

Answer

Correct option: B.
polygenic inheritance
b
(b) : Polygenic (or Quantitative) inheritance is that type of inheritance in which the complete expression of a trait is controlled by two or more genes in which a dominant allele of each gene contributes only a unit fraction of the trait and total phenotypic expression is the sum total of a additive or cumulative effect of all the dominant alleles of genes/polygenes. Human skin colour is an example of such polygenic inheritance which is controlled by three pairs of polygenes $A, B$ and $C$. Negro/black colour is due to presence of all the six dominant contributing alleles $AABBCC$. Very light colour or white colour is due to presence of all six recessive non­contributing alleles $aabbcc.$

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