Question

You decide that you want to replicate some of Mendel’s original results. You begin your experiment with plants that have true breeding traits, one set of plants that have purple flowers and round seeds, the other with white flowers and wrinkled seeds. You do a cross and the progeny (F1 generation) are all purple flowering and produce round seeds. What is the probability that a cross between two F1's will yield offspring that are white and with wrinkled seeds? Seed shape and flower color are unlinked genes in this plant.

Fill in the blanks in order. Prophase I of meiosis involves an intimate association of the ___ through a pairing process called synapsis. During this process, in which there is ____, a reciprocal exchange event called ____ occurs.

Answer 1

Since F1 progeny are all purple flowering and produce round seeds, that means purple flower and round seeds are dominant traits. So white flowers and wrinkled seeds are recessive traits. In Mendel's classic dihybrid cross, when the F1 generation are crossed with each other, a 9:3:3:1 ratio is seen in F2 progeny, for Purple round: Purple wrinkled :White round : white wrinkled.

So, the probability of F1 cross producing white wrinkled plant is 1 / (9+3+3+1) = 1/16

Prophase I of meiosis involves an intimate association of the chromosomes through a pairing process called synapsis. During this process, in which there is chromosomal modification, a reciprocal exchange event called crossing over occurs.