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

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYPrinciples of Inheritance and Variation4 Marks
Question
Differentiate between the following:
  1. Polygenic inheritance and Pleiotropy.
  2. Dominance, Codominance and Incomplete dominance.
✓

Answer

  1. Pleiotropy: 
  • In this, a single gene controls more than one phenotype.
  • The F, resembles one of the parents, i.e., dominant parent.
  • There is no gradation in the phenotype.
  1. Dominance:
  • It is the phenomenon in which one allele of a gene expresses itself and suppresses the expression of the other (recessive) allele of the same gene, when they are present together in a hybrid
  • The hybrid resembles one of the parents.
  1. Codominance:
  • It is the phenomenon in which two alleles of a gene are equally dominant and express themselves in the presence of the other.
  • The hybrid shows characters of both the parents.
  1. Incomplete dominance:
  • It is the phenomenon in which neither of the two alleles of a gene is completely dominant over the other.
  • The hybrid is intermediate between the two parents.

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