Question

in pea plants purple flowers dominate white. what would be the genotypic ratio of a cross between 2 heterzygous purple flowers?
○ 3 homo purple: 1 recessive
○ 3 white : 1 purple
○ all hetero purple
○ 1 homo purple : 2 hetero: 1 recessive

Explanation:

Step1: Define Genotypes

Let \( P \) be the dominant (purple) allele, \( p \) be the recessive (white) allele. Heterozygous purple flowers have genotype \( Pp \).

Step2: Set Up Punnett Square

Cross \( Pp \times Pp \). The Punnett square has four cells:

• Top - left: \( P \times P = PP \) (homo purple)
• Top - right: \( P \times p = Pp \) (hetero purple)
• Bottom - left: \( p \times P = Pp \) (hetero purple)
• Bottom - right: \( p \times p = pp \) (recessive)

Step3: Count Genotypes

• \( PP \): 1
• \( Pp \): 2
• \( pp \): 1

So the genotypic ratio is \( 1 \) homo purple : \( 2 \) hetero : \( 1 \) recessive.

Answer:

D. 1 homo purple : 2 hetero: 1 recessive (assuming D is the identifier for this option, as per the order in the question)