Mendel's Law of Dominance - Practice Questions & MCQ

• Based on his observations on monohybrid crosses Mendel proposed two general rules to consolidate his understanding of inheritance in monohybrid crosses. 
• Today these rules are called the Principles or Laws of Inheritance: the First Law or Law of Dominance and the Second Law or Law of Segregation.
• Since, monohybrid crosses focussed on one pair of contrasting characters, which is controlled by one gene or a pair of alleles, hence the inheritance of both the alleles was studied.

Law of Dominance:

• Characters are controlled by discrete units called factors, now called alleles.
• Factors or alleles occur in pairs.
• In a dissimilar pair of factors one member of the pair dominates the other.
• The allele which expresses itself in the hybrid or heterozygous condition is called the dominant allele and the other allele which is unable to express in the heterozygous condition is called recessive allele.

Significance of Law of Dominance:

• It explains the expression of trait of only one of the parents in F1 generation. 
• It explains the phenotypic ratio of 3:1 in F2 progeny.
• It indicates the superiority of mixed population as it hides many of the defective recessive alleles.