Question

A plant species has two possible gene variations for seed shape. One plant has smooth seeds, and another has wrinkled seeds. There is a no chance that their offspring will be born with wrinkled seeds. What can you conclude from this information?
The plant with smooth seeds is heterozygous for the dominant trait.




Both plants are heterozygous for smooth seeds.




The plant with the smooth seeds is homozygous for the dominant trait.




One parent is homozygous, and the other is heterozygous for the dominant trait.




Both genes are codominant in the offspring.

Answer 1

The plant with the smooth seeds is homozygous for the dominant trait.

Answer 2

Answer: The correct answer is- The plant with the smooth seeds is homozygous for the dominant trait.

According to the Mendelian genetics, dominant trait is the one that expresses itself and masks the expression of the recessive trait. Dominant is depicted with capital letter and recessive with small letter.

Let us consider 'S' depicts the allele for smooth seed and 's' for the wrinkled seeds. There can be two genotypes for smooth seeds that is 'Ss' and 'SS' whereas only one genotype is possible for wrinkled ( 'ss') seeds.

As per the question, there is no chance of the offspring born with wrinkled seeds. This is only possible when the parental plant with smooth seeds is homozygous for the dominant trait ( like SS) . Therefore, only smooth trait will be visible in the offsprings ( with genotype Ss) of the parental plants and there will be no chance of wrinkled seeds (ss) in the offsprings.