Question

Using Punnett square, try to find out the nature of offspring of a test cross. What ratio did we get?

Answer 1

Part 1 : Introduction of Test cross
A test cross is a cross between an unknown genotypic individual with a known homozygous recessive individual. A recessive allele will always be masked by a dominant allele. Therefore the phenotype of any of the offspring will reflect the genotype of the unknown parent. It is used to identify the genotype of an unknown dominant individual.

Part 2: Case 1-Test cross with homozygous dominant
Case 1- When the individual in question is homozygous dominant.

In this case, the result would be all heterozygous tall progeny.

Part 3: Case 2-Test cross with heterozygous dominant
Case 2- When the individual in question is heterozygous dominant.

In this case, the result would be heterozygous tall and homozygous dwarf progeny in a ratio of 1:1.