Question

You have a pea plant with purple flowers, but you are unsure of its genotype. since purple flowers is the dominate trait (p), while the recessive trait is white flowers (p), you decide to conduct a test cross to determine the genotype of the purple flowered pea plant. show how you would do this.

Answer 1

To ascertain the genotype of a purple-flowered pea plant, perform a test cross using a plant with homozygous recessive white flowers (pp). A Punnett square can predict offspring phenotypes to reveal the unknown genotype (PP or Pp) of the purple-flowered plant.

Step-by-step explanation:

To determine the genotype of a pea plant with purple flowers when purple (P) is the dominant trait and white (p) is the recessive trait, you would perform a test cross with a plant that you know is homozygous recessive (pp) for the flower color trait. A test cross involves breeding the unknown genotype with a homozygous recessive individual because any appearance of the recessive phenotype in the offspring indicates the presence of the recessive allele in the tested parent.

To show this, you would set up a Punnett square with the unknown genotype represented as P_ (where the underscore represents an unknown allele which could be either P or p) and cross it with pp. If all offspring have purple flowers, the unknown parent is likely homozygous dominant (PP). If some offspring have white flowers, the unknown parent is heterozygous (Pp).

For example:

• If the unknown genotype is PP, crossing PP x pp would result in all Pp offspring, meaning all would have purple flowers.

• If the unknown genotype is Pp, crossing Pp x pp would result in a 1:1 ratio of Pp (purple flowers) and pp (white flowers) offspring.

This cross will reveal the genotype of the purple-flowered plant based on the flower colors of the offspring. If any white flowers appear, it confirms the presence of a recessive allele (p).