Question

Explain the law of Dominance using a monohybrid cross.​

Answer 1

Answer:

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 F1generation 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 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.

Answer 2

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This is the first law of inheritance. The main principle is as following :-

• Characters are controlled by discrete units called factors.

• Factors occur in pairs.

• In a dissimilar pair of factors one member of the pair dominates the other (= recessive).

The law of dominance is used to describe the demonstration of only one of the pasental doings in a monohybrid cross in the F1 and the expression of both in the F2. This is also explains the proportion of 3:1 which is obtained at the F2.

Mendel demonstrated such experiment in pisum sativum. He crossed between a tall and a dwarf plant of pisum sativum and obtained all tall plants in F1 generation but 3 tall and 1 dwarf in F2. generation.