Question

in cats, the gene for coat color is located in the x chromosomes. one allele codes for orange coat (xb) and the other allele codes for black coat (xb). a black male cat and a calico female cat are crossed. what is the phenotypic ratio?

Answer 1

When a black male cat with genotype XbY and a calico female cat with genotype XBxb are crossed, the phenotypic ratio of their offspring would be 1 black female, 1 calico female, 1 black male, and 1 orange male, representing a classic sex-linked inheritance pattern.

Step-by-step explanation:

Phenotypic Ratio of Offspring from a Black Male Cat and a Calico Female Cat

The gene for coat color in cats is sex-linked and located on the X chromosome, with the allele for orange coat (XB) and the allele for black coat (xb). Since male cats have only one X chromosome, a black male would have the genotype XbY. Female cats have two X chromosomes, and a calico female, having both black and orange patches, is typically XBXb, because the presence of two different alleles results in a tortoiseshell or calico pattern due to X inactivation during embryonic development. When a black male (XbY) and a calico female (XBXb) are crossed, the potential offspring are as follows:

• Female black (XbXb)
• Female calico (XBXb)
• Male black (XbY)
• Male orange (XBY)

Thus, the phenotypic ratio of the offspring would be:

1. 1 black female
2. 1 calico female
3. 1 black male
4. 1 orange male

This is an application of sex-linked inheritance, where certain traits are linked to sex chromosomes and exhibit unique patterns of inheritance.