One line with red flowers and the other line with violet flowers. You carry out a monohybrid cross and find that all of the F1 offspring have violet flowers, while 97 of 400 F2 offspring have red flowers. Explain the inheritance of flower colour in this plant species.

See the answer below

Explanation:

The inheritance of flower color in the plant species follows the simple dominance/recessive inheritance of Mendel. The red flower trait did not show up at all at F1 only for it to show up at F2. It simply means that the red flower trait is recessive while the violet flower color is dominant.

Assuming that the allele for violet flower color is designated as R while that of red flower color is designated as r.  The genotype of the violet flower would be true-breeding, RR, while that of red flower color would also be true-breeding rr:

                RR    x    rr

 F1         Rr    Rr    Rr    Rr  

phenotype ratio = all violet flower color

                 Rr    x    Rr

F2          RR    Rr    Rr    rr

phenotype ratio = 3/4 violet flower color and 1/4 red flower color

97 red flower offspring out of 400 is approximately 1/4.

Hence, the inheritance of flower color in the plant obeys a simple dominant/recessive Mendelian law with the violet color trait dominant over the red color trait.