Question

A test cross is carried out to

• A. Predict whether two traits are linked
• B. Assess the number of alleles of a gene
• C. Determine whether two species or varieties will breed successfully
• D. Determine the genotype of a plant at F${}_2$

Answer 1

The correct option is D Determine the genotype of a plant at F${}_2$

When a tall plant from F${}_1$ or F${}_2$ has TT or Tt composition, its genotype cannot be predicted. Therefore, to determine the genotype of a tall plant at F${}_2$, Mendel crossed the tall plant from F${}_2$ with a dwarf plant. This, he called a test cross. In a typical test cross, an organism showing a dominant phenotype (and 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.

So, the correct answer is ' Determine the genotype of a plant at F${}_2$