Question

Flower position, stem length, and seed shape are three characters that Mendel studied. Each is controlled by an independently assorted gene and has a simple dominant recessive relationship as follows: axial A / terminal a round R / wrinkled r tall T / dwarf t If a plant that is heterozygous for all three characters is allowed to self-fertilize, what is the probability that the offspring would be homozygous dominant for all three traits? Hint: Use the rules of probability rather than making a huge punnet square.

Answer 1

Answer:

1/64

Explanation:

The probability of the offspring being homozygous dominant for the three alleles is 1/64.

Since the three characters assort independently, the probability of the offspring being homozygous dominant for all the three traits is an independent event.

For independent events, the probability of all the events happening together is the multiplication of individual event's probability.

For a cross involving two heterozygotes, taking tall/dwarf for example:

Tt   x   Tt = TT, 2Tt, tt

The probability of obtaining a homozygous dominant genotype is 1/4.

Hence, the probability of the offspring being homozygous dominant for the three alleles will be:

1/4 x 1/4 x 1/4 = 1/64