Chapter 13, Problem 9A

Summary Introduction

To determine:

Whether a test cross can be used to know genotype for polygenic traits.

Introduction:

Each organism receives two version of the same gene, and these versions are termed as alleles. If different alleles are present in the gene, then the dominant allele will express itself and mask the effect of recessive allele. So, there are two types of alleles, dominant allele and recessive allele.

Explanation of Solution

Height, color, and other features are controlled by various genes and each gene contributes the overall outcome of the trait. This type of inheritance is termed as polygenic inheritance. The test cross for polygenic trait is not as easy as monohybrid test cross. This is because, test cross for polygenic trait will produce offspring with much variations for the same trait. Due to this, it would not be easy to determine, which allele is dominant over which allele. But the best thing to create a test cross is to take one parent that is recessive for all traits.