Question

How can you find out the genotype of a pea plant that produces violet flowers?

• A. By selfing
• B. By crossing it with a plant showing dominant phenotype for flower colour
• C. By crossing it with a plant showing recessive phenotype for flower colour
• D. By performing a reciprocal cross

Answer 1

The correct option is C By crossing it with a plant showing recessive phenotype for flower colour

In pea plants, violet colour of flowers is dominant over white colour of flowers.

Let P and p be the alleles responsible for violet and white colour of flowers respectively.

Hence the genotype of the plant producing violet flowers is either PP or Pp.

To find out the genotype, whether it is heterozygous dominant (Pp) or homozygous dominant (PP), a test cross is conducted.

In test cross, an organism showing a dominant phenotype for a particular character is crossed with the plant showing recessive phenotype for the same character.

Hence, the plant producing violet flowers is crossed with a plant producing white flowers (pp).

If all the offspring obtained from this cross produce violet flowers then the genotype is homozygous dominant (PP).

If offspring obtained in the cross produce violet and white flowers in the ratio of 1 : 1, then the genotype is heterozygous dominant (Pp).