Final answer:
Plants with ccPp genotype have white petals due to the absence of the dominant allele P for purple flowers, while CcPp genotype plants have purple petals as they have at least one P allele. Genotypes and phenotypes of a PpYY and ppYy cross in pea plants can be shown through a 2x2 Punnett square.
Step-by-step explanation:
An explanation for why plants with the ccPp genotype have white petals while plants with the CcPp genotype have purple petals is due to the genetic principles of dominance and recessiveness in Mendelian inheritance. In the given scenario, the allele for purple flowers (P) is dominant over the allele for white flowers (p), and the presence of at least one P allele results in purple flowers. Therefore, a plant with CcPp will have purple petals because it has at least one dominant allele P, while a plant with ccPp will have white petals since it lacks any dominant allele P for flower color. The use of a Punnett square can illustrate these genetic combinations.
For a cross between PpYY and ppYy pea plants, the possible genotypes for seed color and texture can be determined through a 2x2 Punnett square. The genotypes are PpYY (purple flowers with yellow peas), PpYy (purple flowers with yellow peas), ppYY (white flowers with yellow peas), and ppYy (white flowers with yellow peas). Approximately 75 percent of offspring from this cross will have purple flowers while 25 percent will have white flowers, reflecting the dominant nature of the purple flower allele.