Question

A breeder crossed a pure bred tall plant having white flowers to a pure bred short plant having blue flowers. He obtained $202$ $F_1$ progeny and found that they are all tall having white flowers. Upon selfing these $F_1$ plants, he obtained a progeny of $2160$plants. Approximately, how many of these are likely to be short and having blue flowers?

Answer 1

In a dihybrid cross, the ratio of F2 generation is 9:3:3:1.

Here, 9 = white flowered and tall plants

3 = white flowered and dwarf plants

3 = blue flowered and tall plants

1 = blue flowered and dwarf plants

If the total number of F2 progeny is 2016, then the number of short plants with blue flowers (double) recessive will be 1*2160/16, which is 135 plants.