Question

Incomplete dominance was discovered by

• A. Correns
• B. Mendel
• C. Johannsen
• D. Bateson

Answer 1

The correct option is A Correns

Karl Correns discovered incomplete dominance in which none of the factors of a gene is dominant, the phenotype of the heterozygous dominant individual is the blend of dominant and recessive traits. He studied flower colour in Mirabilis jalapa and showed that a monohybrid cross between two pure varieties one with red flower petals another with white flower petals gives pink-flowered F${}_1$ plants. If these pink-flowered F${}_1$ plants are crossed, the F${}_2$ plants appear in a ratio of 1 : 2 : 1, having red, pink, or white flower petals, respectively. Pink-flowered plants are heterozygotes with a petal colour intermediate between the red and white colours of the homozygotes. Here, dominant allele (R) specifies red pigment colour, and recessive allele specifies no colour (r) and the flower petals have a white background colour. The pink heterozygotes (Rr) have about half the red pigment of the flowers in red homozygotes (RR) because the heterozygotes carry only one copy of “R” allele that produces colour, while the homozygotes have two copies.