Introduction: Punnett squares allow geneticists to determine the possible genotypes of offspring when the genotypes of parents are known. The genes of one parent are arranged across the top of the square, and the genes of the other parent are arranged down the side, much like a multiplication table. The possible genotypes of offspring are also determined in a manner similar to a multiplication table - by taking the gene represented on the top and the gene represented along the side and placing both in their corresponding boxes (see below).
Setup: Gregor Mendel, the "Father of Modern Genetics" (See Genetics Tutorial), did his historic experiments on heredity in pea plants. He noted that most pea plants were tall, but some were short. He also noted that some tall pea plants always produced tall plants, but some produced a mixture of short and tall. All short plants produced more short plants.
Today, this is known as a Mendelian pattern of inheritance. The tall trait (T; represented with a capital letter) in pea plants is dominant, or seems to "mask" a recessive trait (shortness; represented with the lower-case letter t). When a plant inherits two tall genes, it is a tall plant. When it inherits a tall gene and a short gene, it is also a tall plant. However, when it inherits two short genes, it is a short plant. For more detailed information on dominance and recessiveness, see the Genetics Tutorial.
How to Play: This is a very simple game based on the information above. First, choose a trait (dominant or recessive; upper-case or lower-case) for each box. (If you do not choose a trait for every box, blank spaces will be filled in for you.) Next, write down what you think the genotypes of the offspring (shown in the center boxes) will be. When you have done this, click "Complete the Square" to show the correct answers. Give yourself one point for every correct answer and zero points for every incorrect one.
Bonus: To accumulate bonus points, write down both genotypes and phenotypes (physical appearance; tall or short) before clicking "Complete the Square". Scoring is the same as above. The maximum possible score is eight points.
Created by Kate Stafford and Michael Mannor for ThinkQuest.