Question

A plant with purple flowers was crossed with white flowers producing 50 plants with only purple flowers. On selfing, these plants produced 482 plants with purple flowers and 162 plants with white flowers. What gametic mechanism accounts for these results? Explain.

Answer 1

Hint: A homozygous parent produces all gametes that are similar, whereas heterozygous parent produces two sorts of gametes in equal quantitative relation. The key gametic mechanisms involved here are Mendel’s two important laws.

Complete answer: The law of dominance states that when two alleles of associate degree transmissible combine are heterozygous, then, the allelomorph that is expressed is dominant, whereas the allelomorph that is not expressed is recessive. In this experiment, the purple colour dominates over white colour, therefore, the F1 generation is purple. But as per the law of segregation, just one of the two-factor copies in associate degree is distributed to every reproductive cell (egg or spermatozoon cell) that it makes, and also the allocation of the factor is random, throughout the F2 generation moment of reproductive cell formation. Genes are available in totally different versions or alleles. A dominant allelomorph hides a recessive allelomorph and determines the organism's trait. For seed colour, the dominant purple allelomorph hides the recessive white allelomorph.

Additional information: In the year 1860, Gregor Johann Mendel who is the father of genetics unlocked the mystery of genetics. He conducted many experiments on the pea plants and observed their pattern of inheritance. He explained the law of dominance using the pea plant.

Note: Gregor Mendel came up with the laws. He also came up with a way to find out whether an organism with dominant phenotype is heterozygote or homozygote. This technique is called a test cross and is still used today by animal and plant breeders.