CER QUESTION (worth 15 points)
Scenario:Imagine a special breed of "mystery flowers" where petal color is determined by a single gene. A botanist performs two crosses and observes the following:
Cross 1: A pure-breeding red flower is crossed with a pure-breeding white flower. All of their 50 offspring have red petals.
Cross 2: Two of the red-petaled offspring from Cross 1 are then crossed with each other. From this second cross, the botanist observes 100 flowers, and they have both red petals and white petals.
Your Task (CER Format):
a. Claim: Determine the dominant and recessive petal colors in these mystery flowers, and state the genotypes of the parents used in Cross 1 and Cross 2.
b. Evidence:
*Explain how the results of Cross 1 provide evidence to identify the dominant and recessive petal colors.
*Create a Punnett Square for Cross 1 to show the genotypes of the parent flowers and their offspring.
*Create a Punnett Square for Cross 2 to show the genotypes of the parent flowers and their offspring, and explain how its results support your claim about dominance/recessiveness and parental genotypes.
*For Cross 2, state the expected genotypic and phenotypic probabilities/ratios of the offspring.
c.Reasoning:
*Explain why your evidence from both crosses logically supports your claim about the dominant and recessive traits and the parental genotypes.
*Discuss how the observed outcomes in both crosses are consistent with Mendel's Law of Dominance.
Use appropriate genetic vocabulary throughout your explanation (e.g., allele, trait, phenotype, genotype, homozygous, heterozygous, pure-breeding, probability, ratio, Punnett square).
See the rubric to ensure you get the greatest amount of points for your answer.
