Question

How would you find a genotype of a tall pea plant bearing white flowers? Explain with the help of a cross. Name the type of cross you would use?

Answer 1

Tallness is a dominating trait and can be expressed in homozygous as well as heterozygous condition also while recessive traits (in pea) are expressed only in homozygous condition. So, to find out the genotype of the tall pea with white plant we will test cross it with a dwarf pea plant bearing white flowers (as it is homozygous). If the progeny shows 1 : 1 ratio between dominating and recessive trait, i.e.,50% progenies are tall with white flowers and 50% are dwarf with white flowers then this proves the experimental plant is heterozygous for the dominating trait. And if all the progenies i.e., 100% plants are tall with white flowers, thus this proves that the experimental plant (Tall with white flower) was homozygous for tallness or the dominant trait.

Answer 2

Hey,

first off all to find the genotype, we can apply the test cross. It will sure provide us the exact genotype cause we have to take the suspect plant and then we cross that plant with the recessive allele of that plant.

tall and white (TT) × tt ( recessive)

Tt×Tt×Tt×Tt

so the genotype is 1:1:1:1