Creating a Genetic Pedigree Chart Genes regulate the shape of pea plant seeds. A pea plant produces either round or wrinkled seeds. In this activity, you will create a lineage of pea plants. You will evaluate the possibility of pea plants exhibiting dominant and recessive traits over four generations

Part A
The letter R indicates round seeds that are dominant over the wrinkled variety, represented by r. Create a Punnett square by selecting the genetic makeup of the parents. You can make the parents both hom ozygous, both heter ozygous, or a combination. Show the possible outcomes of the traits in their offspring.

Part B
Question
Scientists can predict possible lineages by making pedigree charts. They use Punnett squares to determine the four genetic possibilities of the offspring and predict what would happen if these offspring reproduced.

Examine this sample pedigree chart. The key includes symbols for hom ozygous dominant, hom ozygous recessive, and heter ozygous individuals.

Part C
Using the pedigree chart you made, explain why scientists use the word dominant for certain traits.

Part D
The lineage of pea plants produced round seeds for four generations. The plants that fertilized these pea plants also produced round seeds. However, in the fifth generation, the plant produced to two plants with wrinkled seeds. Can that be possible? Explain your answer using your pedigree chart.

Part E
Two students fertilize a pair of pea plants. One plant is Rr, and the other is rr. The offspring produced by these two plants all had the dominant trait. The Punnett square showed that there was a 50 percent chance of the offspring carrying rr genes. So, the student assumes that he made an error in determining the genetic makeup of the plants. Do you think the student made an error, or is there another explanation? Explain your answer.