Chapter 12.1, Problem 3R

Summary Introduction

To analyze:

The genotypes of the parents, based on the given data.

Given:

The number of progeny for each color, produced by a cross between the guinea pigs, having black and albino coat color, is presented in Table 1 as follows.

Table 1: Number of offsprings produced as a result of a cross between the black (B) and albino (b) coat color.

Serial number	Phenotype of parent	Number of black progeny	Number of albino progeny	Parental genotype
1	$\begin{array}{l}\text{Black}\times \text{Black}\hfill \end{array}$	12	0
2	$\text{Albino}\times \text{Albino}$	0	12
3	$\begin{array}{l}\text{Black}\times \text{Albino}\hfill \end{array}$	5	7
4	$\text{Black}\times \text{Black}$	9	3

Introduction:

The phenotype of an organism is the observable traits and genotype refers to the genetic makeup of the organism. The phenotypic traits of an organism are related to its genetic constitution directly. Mendel law of dominance indicates that the recessive allele cannot express itself in the presence of dominant allele. The recessive phenotype is expressed only when present in pure homozygous (bb) state.