Name:______Date:______Hour:______

Pea Plant Genetics

Using your vocabulary definitions, define each of the following terms on this sheet:

Allele:

Homozygous:

Heterozygous:

Phenotype:

Genotype:

Like any other language, the language of genetics consists of symbols and rules for using these symbols. When a trait being studied shows dominance, it is observed in nature much more frequently than if it is a recessive form. The capitalized letter of the dominant form becomes its symbol (Ex. R stands for round peas because it is the dominant pea shape). For the recessive form of the same trait; the symbol letter remains the same but not capitalized (Ex. r stands for wrinkled peas because it is the recessive pea shape). Complete the following chart using these rules.

1. Write the correct allele symbol in each box.

For Pea Plants: / Pod
Shape / Height / Flower Color / Pod Color / Pea
Color / Pea
Shape / Flower Position
Dominant Traits: / smooth pods / tall stems / purple flower / green pods / yellow peas / round peas / axial flowers
Dominant Allele Symbol: / S
Recessive Traits: / constricted pods / short stems / white flowers / yellow pods / green peas / wrinkled peas / terminal flowers
Recessive Allele Symbol: / s

Name:______Date:______Hour:______

2.  Using the symbols from the above chart, write the allele symbols that would be present in the following homozygous pea plants. Next, indicate whether they are going to express the dominant or recessive trait.

Trait / Homozygous Alleles / Is this the dominant or recessive trait?
Tall stems
Terminal flowers
White flowers
Yellow Peas
Smooth Pods
Yellow Pods

3. Write the symbols for the following heterozygous:

Traits / Heterozygous Alleles
Yellow Peas
Axial Flowers
Green Pods
Purple Flowers
Round Peas
Smooth Pods
Tall Stems

Name:______Date:______Hour:______

4. The following letters represent pairs of alleles. Indicate weather each pair is heterozygote or homozygote. Then indicate whether each pair would display a dominant or recessive phenotype.

Genotype
(What are the alleles ) / Phenotype
(What trait will show up?) / Heterozygous or Homozygous (circle one) / Dominant or Recessive (circle one)
Tt / Heterozygous or Homozygous / Dominant or Recessive
Rr / Heterozygous or Homozygous / Dominant or Recessive
yy / Heterozygous or Homozygous / Dominant or Recessive
PP / Heterozygous or Homozygous / Dominant or Recessive
Gg / Heterozygous or Homozygous / Dominant or Recessive
ss / Heterozygous or Homozygous / Dominant or Recessive

Complete the following Punnett Squares

5) A plant with green pea pods (Gg) is crossed with a plant that has yellow pea pods (gg).

Parent 1 Alleles / Parent 2
Alleles
Possible Gamete Alleles

Name:______Date:______Hour:______

All resulting genotypes:

All resulting phenotypes:

How many are green? ______How many are yellow? _____

Genotypic Ratio-______:______

Name:______Date:______Hour:______

6) A tall plant (TT) is crossed with a tall plant (Tt).

Parent 1 Alleles / Parent 2
Alleles
Possible Gamete Alleles

Name:______Date:______Hour:______

All resulting genotypes:

All resulting phenotypes:

How many are tall? ______How many are short? ______

Genotypic Ratio-______:______

Name:______Date:______Hour:______

7) A white flower (pp) is crossed with a white flower (pp).

Parent 1 Alleles / Parent 2
Alleles
Possible Gamete Alleles

Name:______Date:______Hour:______

All resulting genotypes: How many are purple? ______How many are white? ______

All resulting phenotypes: Genotypic Ration- ______: ______