Flower diameter in sunflowers is a quantitative trait. A plant with 6-cm flowers, from a highly inbred strain, is crossed to a plant with 30-cm flowers, also from a highly inbred strain. The F₁ have 18-cm flowers. F₁ × F₁ crosses yield F₂ plants with flowers ranging from 6 to 30 cm in diameter, in approximately 4-cm intervals (6, 10, 14, 18, 22, 26, 30). The number of different genes influencing flower diameter in this plant is: A) three. B) four. C) five. D) six. E) seven.

Question

Quizplus · Accepted Answer

The range of flower diameters in the F2 generation suggests that there are 7 phenotypic classes (6, 10, 14, 18, 22, 26, 30). The number of genes (n) can be estimated using the formula 2n + 1 = number of phenotypic classes. Solving for n gives 2n + 1 = 7, so n = 3.

Flower Diameter in Sunflowers Is a Quantitative Trait