Question

Complete dominance is not shown by
A) Lathyrus
B) Pisum sativum
C) Mirabilis jalapa
D) Oenothera

Answer 1

Hint: Complete dominance can be described as a phenomenon where upon crossing a dominant and recessive phenotype, only the dominant phenotype is seen in the F1 generation. For example, if a tall plant and a dwarf plant is crossed where the tall is the dominant phenotype, the F1 generation will show all tall phenotypes.

Complete answer:
A classic example of incomplete dominance is seen in Mirabilis jalapa plant.
The popular example is seen in case of inheritance of flower colour in this plant.
A plant with white flowers, where white colour is the recessive homozygous character, is crossed with a plant with red flowers, where red colour is the homozygous dominant character.
The first generation will have hybrid offspring, having all pink flowers. This is an intermediate character.
If we further cross this hybrid intermediate pink colour plants then in F2 generation we will have red, pink and white colour plants in a ratio of 1: 2: 1.

So, the correct answer is option C. Mirabilis jalapa.

Note:
Incomplete dominance can be described as a phenomenon in which upon crossing a dominant and recessive phenotype an intermediate phenotype appears in the F1 generation. Taking the same example as above, an intermediate height of the plant will be seen in the F1 generation. Here is a diagram of the punnett square of the incomplete dominance of Mirabilis jalapa: