Question

The ratio of 9:3:3:1 is due to
A. Segregation of characters
B. Independent assortment of genes
C. Crossing over of chromosomes
D. Homologous pairing between chromosomes

Answer 1

Hint: Inheritance is defined as the process of how the offspring receives the genetic information from the parent, and the whole process of hereditary is dependent on the inheritance, so that is the reason why the offspring looks similar to parents.

Complete answer:
In order to explain the law of inheritance, Mendel proposed 3 laws, which includes
> Law of dominance
> Law of segregation and
> Law of independent assortment
Among all laws the given ratio 9:3:3:1 is due to the law of independent assortment.
In order to explain this, an example will be given, a cross is made between two parents with two different contrasting characters, and this type of cross is called a dihybrid cross. The two parents with two contrasting characters are Homozygous yellow round (YYRR) and heterozygous green wrinkle ( yyrr).
When the cross is done in the F1 generation, all plants with heterozygous yellow round are produced, when these plants are subjected to self-pollinated, in F2 generation following plants are produced which are, 9 plants yellow round, and 3 plants yellow wrinkle, and 3 plants green round and 1 plant with green wrinkle seeds are seen. And this type of phenotypic dihybrid ratio 9:3:3:1, and Mendal state that this is one of the laws of independent assortment.

So the answer is option B.

Note: Independent assortment of genes is described as how different genes separated from each other when the reproductive cells develop, and the independent assortment of genes and their traits can be easily explained by a dihybrid test cross.