A polygenic inheritance in human beings is
Correct answer: A. Skin colour
- A. Skin colour
- B. Phenylketonuria
- C. Colour blindness
- D. Sickle cell anaemia.
Explanation
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 color is an example of such polygenic inheritance which is controlled by three pairs of polygenes A, B and C. Negro/black color is due to presence of all the six dominant contributing alleles AABBCC. Very light color or white color is due to presence of all six recessive non-contributing alleles aabbcc.
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About Inheritance
Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.
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