Question

Imagine that horn color in Hodags (folkloric creatures of Wisconsin) is controlled by a single gene. You mate a Hodag homozygous for a bright orange horns (COCO) with a Hodag homozygous for ivory horns (CICI). Numerous offspring are produced, all with pale orange horns. You cross an orange-horned Hodag with an ivory-horned Hodag and get an F₁. You then cross two F₁ individuals. What phenotypic ratio would you expect in the F₂ generation?

A. 9 bright orange: 6 light orange: 1 ivory
B. 1 bright orange: 2 light orange: 1 ivory
C. 3 bright orange: 1 ivory
D. 1OO: 2OI: 1II
E. 3OO: 1 II

Answer 1

When crossing two F1 Hodags with intermediate pale orange horns, the expected phenotypic ratio of the F2 generation is 1 bright orange:2 pale orange:1 ivory. The correct option is B.

Step-by-step explanation:

When crossing a Hodag homozygous for bright orange horns (COCO) with a Hodag homozygous for ivory horns (CICI), we see that all offspring have pale orange horns, indicating incomplete dominance.

In the case of a monohybrid cross with incomplete dominance, like this example with Hodags, the F1 generation exhibits this intermediate phenotype. When crossing two F1 Hodags, both heterozygous (COCI), the resulting F2 generation displays a phenotypic ratio of 1:2:1.

This ratio consists of 1 bright orange (COCO), 2 pale orange (COCI), and 1 ivory (CICI). The correct option is B.