Question

The expression of only one of the parental characters in F1 is not applicable for one gene or two gene interaction showing F2 progeny with
A. Two phenotypes and three genotypes with respect to plant height in pea.
B. Four phenotypes and nine genotypes with respect to plant height and flower in pea.
C. Two phenotypes and two genotypes in test cross w.r.t plant height in pea.
D. Three phenotypes and three genotypes with respect to flower color in snapdragon.
E. Five phenotypes and nine genotypes with respect to kernel color in wheat.
A) B and D
B) A, D, and E
C) D and E
D) B, C, and D

Answer 1

The expression of only one of parental characters in F1 for one gene or two interactions showing F2 progeny is only applicable when following the Mendelian pattern of inheritance.

Complete answer: 1. The first three conditions- Two phenotypes and three genotypes with respect to plant height in pea, four phenotypes, and nine genotypes with respect to plant height and flower color in pea and Two phenotypes and two genotypes in test cross with respect to plant height in pea, are following the Mendelian pattern of inheritance.
2. The fourth condition is three phenotypes and three genotypes with respect to flower color in snapdragon follow the pattern of incomplete dominance.
It is the condition when there is no dominance of one allele over the other.
3. The fifth condition that is five phenotypes and nine genotypes with respect to kernel color in wheat is an example of polygenic inheritance. In polygenic inheritance, two or more genes control a single inherited trait.

So, the correct answer is “Option C. D and E ”.

Additional Information: The Mendelian pattern of inheritance is based on two laws- law of segregation and law of independent assortment.
Law segregation is based on a monohybrid cross and states that each individual has two copies of a gene and during the gamete formation paired genes separate from each other and each gamete receives only one gene. This is also known as the law of purity of gametes.
The Law of independent assortment is based on a dihybrid cross.
It states that during gametogenesis the assortment of one pair of genes is not dependent on the other pair. Due to this independent assortment of characters, offspring are produced with a new combination of characters.

Note: Polygenic inheritance can be seen in traits like skin color, human height, eye color, etc.
It is a non-epistatic type of inheritance which means the expression of one gene is not masked by the other gene. In polygenic inheritance, continuous variation of a phenotypic trait can be seen.