Question

State the principle of dominance with an illustration.

Answer 1

Hint: According to the law of dominance when two different alleles are present, the dominant allele will express itself. The recessive allele characters will not be lost, they are also present but they are suppressed.

Complete answer:
In this question we have asked about the law of dominance. Law of dominance is one of the principles of Mandal's laws of inheritance. According to the law of dominance, when an organism is heterozygous for a trait, which means two different alleles are present for a trait, only the dominant allele will produce a phenotype.

Let's take an example to understand law of dominance:

In this diagram you can see, we have two parents with different phenotypic characters. One parent is tall and the other is dwarf. When we cross a tall plant with a dwarf plant, all the offspring (F1 generation) forms are tall, which means they are showing phenotypic character of only one parent. But genotypically, they have alleles from both parents. So, we can say that tall is dominant over yellow.

When we cross F1 generation, we see that the half offsprings are tall and half is dwarf, which proves that the dwarf allele is not lost but suppressed by the tall allele. This example proves that when one allele is dominant over another in a heterozygous animal, only the dominant phenotype is seen.

Additional information:
Incomplete dominance is when a dominant allele does not completely mask the effects of a recessive allele, and the offspring's physical appearance shows a blending of both alleles. It is also called semi-dominance or partial

Note: Mendel gives three laws of inheritance , which includes 1)law of dominance, 2)law of segregation and 3)law of independent assortment. We already explain the law of dominance. Law of segregation states that alleles segregate randomly into gametes and the law of independent assortment states that during a dihybrid cross, an assortment of each pair of traits is independent of the other.