Question

phenotypes: ______ phenotypic ratio: ______

1. tall plants are dominant over short plants in pea plants. fill in the punnett square and determine the expected genotypic and phenotypic ratios from crossing heterozygous and heterozygous parents.

genotypes: ______ genotypic ratio: ______
phenotypes: ______ phenotypic ratio: ______

Explanation:

Step1: Define alleles

Let \( T \) represent the dominant allele (tall) and \( t \) represent the recessive allele (short). Both parents are heterozygous, so their genotype is \( Tt \).

Step2: Set up Punnett square

Each parent can contribute either \( T \) or \( t \). The Punnett square is constructed by combining the alleles from each parent.

Step3: Determine genotypes

From the Punnett square, the possible genotypes are \( TT \) (top - left), \( Tt \) (top - right and bottom - left), and \( tt \) (bottom - right). Counting the occurrences: \( TT = 1 \), \( Tt=2 \), \( tt = 1 \), so the genotypic ratio is \( 1:2:1 \).

Step4: Determine phenotypes

• \( TT \) and \( Tt \) genotypes result in the tall phenotype (since \( T \) is dominant).
• \( tt \) genotype results in the short phenotype.

Counting the phenotypes: Tall ( \( TT + Tt+ Tt \)) = 3, Short ( \( tt \)) = 1, so the phenotypic ratio is \( 3:1 \).

Answer:

Punnett Square:

	T	t
t	Tt	tt

Genotypes: TT, Tt, tt

Genotypic Ratio: 1 (TT) : 2 (Tt) : 1 (tt)

Phenotypes: Tall, Tall, Short

Phenotypic Ratio: 3 (Tall) : 1 (Short)