Q.4.  Explain the Law of Dominance using a monohybrid cross.

Mendel’s law of dominance states that a dominant allele expresses itself in a monohybrid cross and suppresses the expression of recessive allele. However, this recessive allele for a character is not lost and remains hidden or masked in the progenies of ${F}_{1}$ generation and reappears in the next generation.
For example, when pea plants with round seeds (RR) are crossed with plants with wrinkled seeds (rr), all seeds in ${F}_{1}$ generation were found to be round (Rr). When these round seeds were self-fertilized, both the round and wrinkled seeds appeared in ${F}_{2}$ generation in 3: 1 ratio. Hence, in ${F}_{1}$ generation, the dominant character (round seeds) appeared and the recessive character (wrinkled seeds) got suppressed, which reappeared in ${F}_{2}$ generation.