Question

To determine the genotype of a tall plant of $F_2$ generation, Mendel crossed this plant with a dwarf plant. This cross represents a

• A. test cross
• B. back cross
• C. reciprocal cross
• D. dihybrid cross

Answer 1

Answer: (A)

To determine the genotype of a tall plant of $F_2$ generation, Mendel crossed the tall plant from $F_2$ generation with a dwarf plant. He called this a test cross. In a typical test cross an organism (pea plants) showing a dominant phenotype whose genotype is to be determined is crossed with the recessive parent instead of self crossing. The progenies of such a cross can easily be analysed to predict the genotype of the test organism. Normal test cross ratio for a monohybrid cross is $1:1$ and for a dihybrid cross is $1:1:1:1$.