Chapter 20, Problem 1DA

If all white cats died, what proportion of the kittens in the next generation would be white?

Summary Introduction

To determine: Thenumber of white cats produced if all the white cats died in the previous generation.

Introduction: A disorder is the dysregulation or disruption of the structure of the body or function. This is due to the effect of a pathological organism or condition inside the body.

Explanation of Solution

The alleles for the color of the coat of the cat consist of dominant and recessive alleles. The white coat color of the cat is a recessive allele and the black color is the dominant allele. So if the generation consisting of white cats died due to a fatal event, then the number of white cats produced will depend on the number of heterozygous cats that are present in the previous generation. The number of white cats in the subsequent generation can be deduced using Punnett square analysis. The dominant allele for black color in homozygous condition can be “BB” and white color will be “bb”. Hence, the white and black cats produced will be as follows:

Gametes	B	b
B	BB (homozygous black)	Bb (heterozygous black)
b	Bb (heterozygous black)	bb (homozygous white)

Hence, if all the white cats from the given generation die, then the cross between the two heterozygous black cats will again give black and white cats in the ratio 3:1. So the number of cats produced in the next generation will be ¼ of the total offspring.