Law of Dominance: Law of dominance is known as the first law of inheritance. Mendel’s law of dominance states that in a heterozygote, one trait will conceal the presence of another trait for the same characteristic. Rather than both alleles contributing to a phenotype, the dominant allele will be expressed exclusively. The recessive allele will remain “latent,” but will be transmitted to offspring by the same manner in which the dominant allele is transmitted. The recessive trait will only be expressed by offspring that have two copies of this allele; these offspring will breed true when self-crossed.

Law of Dominance

• Law of dominance explains that in a monohybrid cross between a pair of contrasting traits, only one parental character will be expressed in F₁ generation and both are expressed in F₂ generation in the ratio 3:1.
• The one which expressed in F₁ generation is called dominant trait and the one which is suppressed is called recessive trait.
• In simple words, the law of dominance states that recessive traits are always dominated or masked by dominant trait.​
• 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).
• When these round seeds were self fertilized, both the round and wrinkled seeds appeared in F2 generation in 3: 1 ratio.
• Hence, in F1 generation, the dominant character (round seeds) appeared and the recessive character (wrinkled seeds) got suppressed, which reappeared in F2 generation.

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By Team Learning Mantras