Question

The result of Tt $\times$ tt is
A) Test cross
B) Back cross
C) Both A and B
D) None of the above

Answer 1

The test cross is the cross between a recessive phenotype and a dominant phenotype, although the backcross is the cross between the hybrid generation F1 and is one of the two parents.

Complete answer:
First we should know about the importance of test cross and back cross to answer this question. In genetics, test cross and backcross are significant because they are two distinct forms of crosses that are incredibly helpful in determining an animal or a plant's genotype. The key aim of cross and backcross research is to discover organisms' heterozygosity or homozygosity by determining the forms of gametes that contain the dominant genotypes.
Now, let us find the solution from the options-
Testcross is a cross of any genotype exhibiting a dominant phenotype with a recessive homozygote to decide whether it is a heterozygous or homozygous dominant, the genotype of a dominant parent. The dominant phenotype is seen by being a hybrid Tt, and tt is the recessive parent. It is said as a test cross.
In order to deduce the genotype between both parents and the hybrid, the back cross is a cross between the F1 hybrid and either between one of the parents (dominant or recessive). Therefore, a hybrid 'Tt' is crossed with recessive parents; it is said as a back cross.

Thus, the correct answer is option (C) Both A and B.

Note: All test crosses are a form of backcross, but all back crosses are not a form of test cross. In order to determine the genotype (TT or Tt) of the dominant phenotype, a test cross is necessary, while backcross is helpful in retrieving significant parent characteristics.