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LAW OF DOMINANCE USING A MONOHYBRID CROSS

  1. The Law of dominance is given by Mendel, which is stated as below: "In a cross of parental generations that are pure for contrasting traits, only one form of the trait will appear in the next generation. Offspring that are hybrid for a trait will have only the dominant trait in the phenotype."
  2. With reference to monohybrid cross it means that a dominant allele expresses itself in a monohybrid cross and suppresses the expression of recessive allele.
  3. However, the recessive allele is not lost but it is masked by the dominant allele in F1 generation and gets reappeared in next generation.
  4. For example, when pea plants with round seeds (RR) are crossed with plants with wrinkled seeds (rr), all seeds in F1 generation were found to be round (Rr).
  5. When these F1 generation is self fertilized both the round and wrinkled seeds appeared in F2 generation in 3:1 ratio.
  6. This means that the suppressed gene (r) of wrinkled seeds were not omitted from F1 generation, they are just masked by dominant gene (R) of round seeds.

Law of Dominance using a monohybrid cross

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