Question

1. in pea plants, purple flower color (p) is dominant over white flower color (p). use a punnett square to predict the phenotypes and genotypes of a cross between pea plant homozygous for purple flower color and a pea plant homozygous for white flower color. if two plants from the f₁ generation are crossed, what genotypes and phenotypes are expected in the f₂ generation?

Explanation:

Step1: Determine the parental genotypes

The homozygous purple - flowered plant has the genotype \(PP\), and the homozygous white - flowered plant has the genotype \(pp\).

Step2: Create the Punnett square for the \(P\times p\) cross

	\(P\)	\(P\)
\(p\)	\(Pp\)	\(Pp\)

All \(F_1\) offspring have the genotype \(Pp\) (heterozygous) and the phenotype purple flowers (since \(P\) is dominant).

Step3: Cross two \(F_1\) plants (\(Pp\times Pp\))

	\(P\)	\(p\)
\(p\)	\(Pp\)	\(pp\)

Step4: Analyze the \(F_2\) generation

• Genotypes:
• \(PP\): \(\frac{1}{4}\) (homozygous dominant)
• \(Pp\): \(\frac{2}{4}=\frac{1}{2}\) (heterozygous)
• \(pp\): \(\frac{1}{4}\) (homozygous recessive)
• Phenotypes:
• Purple flowers (\(PP + Pp\)): \(\frac{1}{4}+\frac{2}{4}=\frac{3}{4}\)
• White flowers (\(pp\)): \(\frac{1}{4}\)

Answer:

• Genotypes: \(PP\) (homozygous dominant, \(\frac{1}{4}\) of the \(F_2\) generation), \(Pp\) (heterozygous, \(\frac{1}{2}\) of the \(F_2\) generation), \(pp\) (homozygous recessive, \(\frac{1}{4}\) of the \(F_2\) generation)
• Phenotypes: Purple flowers (\(\frac{3}{4}\) of the \(F_2\) generation), White flowers (\(\frac{1}{4}\) of the \(F_2\) generation)