Figure 3.22 (page 120) illustrates reciprocal crosses involving chickens with sex-linked dominant barred mutation. For Cross A and for Cross B, cross the F₁ roosters and hens and predict the feather patterns of roosters and hens in the F₂.

Verified step by step guidance

1. Step 1: Understand the genetic basis of the barred mutation in chickens. The barred mutation is a sex-linked dominant trait located on the Z chromosome. In chickens, males are ZZ and females are ZW.
2. Step 2: Identify the genotypes of the F₁ generation. In reciprocal crosses, the barred trait is dominant, so if one parent is barred, the F₁ offspring will express the barred phenotype. Determine the genotypes of the F₁ roosters (ZZ) and hens (ZW).
3. Step 3: Set up the Punnett square for the F₁ cross. Cross the F₁ rooster (Z^B Z) with the F₁ hen (Z^B W), where Z^B represents the barred allele.
4. Step 4: Determine the possible genotypes and phenotypes of the F₂ generation. Analyze the Punnett square to find the genotypes of the F₂ roosters and hens, and predict their feather patterns based on the presence of the barred allele.
5. Step 5: Conclude with the phenotypic ratios. Summarize the expected phenotypic ratios of barred and non-barred roosters and hens in the F₂ generation based on the genotypes obtained from the Punnett square.

Key Concepts

Sex-Linked Inheritance

Sex-linked inheritance refers to genes located on sex chromosomes, typically the X chromosome in many organisms, including chickens. In this case, the barred mutation is a dominant trait linked to the sex chromosomes, meaning its expression can differ between males and females based on their genetic makeup.

Reciprocal Crosses

Reciprocal crosses involve mating two organisms in both possible combinations to observe the inheritance patterns of traits. This method helps determine whether a trait is sex-linked or autosomal by comparing the offspring's phenotypes from both crosses, providing insights into how traits are passed down through generations.

F₂ Generation Predictions

The F₂ generation is the second filial generation, produced by crossing individuals from the F₁ generation. By analyzing the genotypes and phenotypes of the F₁ roosters and hens, predictions can be made about the feather patterns in the F₂ generation, illustrating the inheritance of the barred mutation and its expression in both sexes.