In Drosophila, brown body colour (B) is dominant to black (b) and long wings (W) are dominant to short wings (w). A researcher crossed a male Drosophila with genotype "BBWW" with a female Drosophila with genotype "bbww". She then crosses two Drosophila of the F₁ generation and draws the F₂ Punnett square in her record book, which is shown below, and you have to fill in the blanks in her Punnett square.