Question

Which of the following is a test cross?

• A. $Tt\times Tt$
• B. $TT\times Tt$
• C. $TT\times tt$
• D. $tt\times Tt$

Answer 1

Answer: (D)

Test cross is determines whether an individual is homozygous or heterozygous for dominant character. The offspring of $F_1$ is crossed with recessive parent. The ratio will be $1:1$ in case of hybrid or heterozygous individual. In case of double heterozygote $(eg,RrYy)$, crossed with recessive $(rryy)$ the ratio will be $1:1:1:1$. Test cross helps to find out genotype of parents.