Mouse Genetics (Two Traits) Vocabulary: allele, genotype, phenotype, probability, Punnett square [Note to teachers and students: This Gizmo was designed as a follow-up to the Mouse Genetics (One Tr ait) Gizmo™. We recommend doing that activity before trying this one.] Prior Knowledge Questions (Do these BEFORE using the Gizmo.) [Note: The purpose of these questions is to activate prior knowledge and get students thinking. Students are not expected to know the answers to the Prior Knowledge Questions.] 1. A single coin is flipped four times. What do you think is the most likely outcome? A. Four heads B. Three heads, one tail C. Two heads, two tails D. One head, three tails E. Four tails F. All are equally likely Answers will vary. [The correct answer is C: Two heads, two tails (3/8 probability).] 2. What do you think are the odds of getting four tails in a row? Explain your answer. Answers will vary. [The correct answer is 1/16, or 6.25%. This is equal to (½)4, or 0.54.] Gizmo Warm-up On the Mouse Genetics (Two Traits) Gizmo, drag mice into the Parent 1 and Parent 2 spaces, and then click Breed to see their offspring. Experiment with different combinations of parent mice. 1. What must be true to have offspring with black fur? At least one parent has black fur. 2. What must be true to have offspring with white fur? Answers will vary. [If both parents are homozygous, then both parents must have white fur. White fur could also result if one or both of the parents are heterozygous for fur color.] 3. What must be true to have offspring with black eyes? At least one parent has black eyes. 4. What must be true to have offspring with red eyes? Answers will vary (see above). 5. What must be true to have offspring with red eyes and white fur? Answers will vary. If both parents are homozygous for these traits, then both parents must have red eyes and white fur. These traits could also result if one or both parents are heterozygous for fur color and eye color