How do you complete a Punnett square?

Answer 1

A punnett square looks like this. Lets say that you had 2 flowers, and you wanted to find the likelihood that their offspring would be purple. Purple is dominant over white. You have one pure purple plant, (PP), and one hybrid purple plant, (Pp). The big P stands for purple, and the little p stands for white. You take the PP and put it on the top, one P over each of the top squares. Then you take the Pp and put each p on one of the side squares. You take one letter from each part of the square, so your four possibilities would be PP, PP, Pp, and Pp. There is no way that the plant could be white.