Question

in peas, yellow seed color (y) is dominant to green seed color (y). a homozygous green seed pea plant is crossed with a heterozygous yellow seed pea plant. what is the predicted phenotypic ratio of the offspring based on seed color?
50 percent yellow, 50 percent green
50 percent yy, 50 percent yy
100 percent yellow, 0 percent green
100 percent yy, 0 percent yy

Explanation:

Step1: Determine Genotypes

Homozygous green: \( yy \) (since green is recessive, only \( yy \) shows green). Heterozygous yellow: \( Yy \) (yellow is dominant, so \( Yy \) shows yellow).

Step2: Set Up Punnett Square

	\( Y \)	\( y \)
\( y \)	\( Yy \)	\( yy \)

Step3: Analyze Phenotypes

• \( Yy \): Yellow (dominant allele \( Y \) present).
• \( yy \): Green (recessive alleles only).

From the Punnett square, 2 out of 4 (50%) are \( Yy \) (yellow), 2 out of 4 (50%) are \( yy \) (green).

Step4: Evaluate Options

• Option 1: 50% yellow, 50% green. Matches our result.
• Option 2: Talks about genotypes (YY, yy), not phenotypes. Eliminate.
• Option 3: 100% yellow. Incorrect, as we have green offspring. Eliminate.
• Option 4: Talks about genotypes (Yy, yy), not phenotypes. Eliminate.

Answer:

50 percent yellow, 50 percent green