Question

In Antirrhinum (Snapdragon), a red flower was crossed with a white flower and in ${ F }_{ 1 }$ generation pink flowers were obtained. When pink flowers were selfed, the ${ F }_{ 2 }$ generation showed white, red, and pink flowers. Choose the incorrect statement from the following:
(a) This experiment does not follow the Principle of Dominance.
(b) Pink flower in ${ F }_{ 1 }$ is due to incomplete dominance.
(c) Ratio of ${ F }_{ 2 }$ is 1/4 (Red): 2/4 (pink): 1/4(White)
(d) The Law of Segregation does not apply in this experiment.

Answer 1

Hint: The incorrect statement is that statement which states that in a heterozygote, one trait will suppress the presence of another trait for the same characteristic. This means that both the alleles will be there in the phenotype but only dominant will be expressed.

Complete answer:
When a red flower was crossed with a white flower in Antirrhinum or Snapdragon, we will observe that in ${ F }_{ 1 }$ generation the flowers obtained were pink in color. When the pink flowers were selfed, then the ${ F }_{ 2 }$ generation showed white, red, and pink flowers. This indicates that the genes responsible for the color of the flower show incomplete dominance. In ${ F }_{ 1 }$ generation the inheritance of the pink color of the flower is an example of incomplete dominance. This indicates that the variation in dominance, where the dominant - recessive relationship is not completely followed in a heterozygote neither the red nor the white-colored flower is developed. In ${ F }_{ 2 }$ generation the appearance of the red-colored flower, the pink-colored flower, and the white-colored flower is in the ratio of 1: 2: 1 respectively. This indicates that the law of segregation does apply in this experiment as each gamete contains an allele and allele segregation takes place normally. From the above explanation, it is clear that the Law of Segregation applies to the experiment.

So, the correct answer is, 'The Law of Segregation does not apply in this experiment'.

Note:
- law or the Principle of Dominance is applicable in the ${ F }_{ 1 }$ generation.
- In ${ F }_{ 1 }$ generation the inheritance of the pink color of the flower is an example of incomplete dominance.
- In ${ F }_{ 2 }$ generation the appearance of the red-colored flower, the pink-colored flower, and the white-colored flower is in the ratio of 1: 2: 1 respectively.
- The law of Segregation is also applied in this experiment.