Question

Genetics Practice - Peas, Please!
1. Pea pods come in two shapes: inflated and
constricted. Inflated is the dominant allele.
Complete the chart:
Genotype Phenotype
2. Show the cross between a homozygous inflated and
a homozygous constricted pea plant.
What is the phenotype of the offspring? _______
3. Show the cross between a heterozygous inflated and
a homozygous constricted pea plant.
How many offspring are inflated? _____
How many offspring are constricted? _____
4. Show the cross between two heterozygous inflated
peas.
How many offspring are inflated? _____
How many offspring are constricted? _____
5. Pea pods come in two colors: yellow and green.
Green is the dominant allele.
Complete the chart:
Genotype Phenotype
6. Show the cross between two yellow pod plants.
What is the phenotype of the offspring? _______
7. Show the cross between a heterozygous green pod
plant and a yellow pod plant.
How many offspring are yellow pods? ____
How many offspring are green pods? ____
8. In pea plants, axial flowers are dominant to terminal
flowers.
A heterozygous axial flowered plant is crossed with one
that has terminal flowers.
How many offspring have axial flowers? _____
How many offspring have terminal flowers? _____
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Genetics Practice - Peas, Please!
1. Pea plants can have either white or purple flowers,
where white is recessive.
Complete the chart:
Genotype Phenotype
2. Show the cross between a homozygous purple flower
plant and a homozygous white flower pea plant.
What is the phenotype of the offspring? _______
3. Show the cross between a heterozygous purple and
a homozygous white pea plant.
How many offspring are purple? _____
How many offspring are white? _____
4. Show the cross between two heterozygous purple
flower pea plants
How many offspring are purple? _____
How many offspring are white? _____
5. Pea plants can either
be tall or short (dwarf),
where the short allele is
recessive.
Complete the chart:
Genotype Phenotype
6. Show the cross between two dwarf plants.
What is the phenotype of the offspring? _______
7. Show the cross between a heterozygous tall plant and
a short plant.
How many offspring are tall? ____
How many offspring are short? ____
8. Show the cross between two heterozygous tall plants.
How many offspring are tall? ____
How many offspring are short? ___

Answer 1

Here are the answers, using capital letters for dominant alleles and lowercase for recessive.

Section 1 — Pod shape (Inflated dominant I, constricted recessive i)
1. Genotype → Phenotype
- II → inflated
- Ii → inflated
- ii → constricted

2. Cross: II × ii
- Offspring genotype: all Ii
- Phenotype of offspring: inflated (all)

3. Cross: Ii × ii (Punnett squares give 2 Ii : 2 ii out of 4)
- Inflated offspring: 2
- Constricted offspring: 2

4. Cross: Ii × Ii (Punnett: 1 II : 2 Ii : 1 ii)
- Inflated offspring: 3
- Constricted offspring: 1

Section 2 — Pod color (Green dominant G, yellow recessive g)
5. Genotype → Phenotype
- GG → green
- Gg → green
- gg → yellow

6. Cross: gg × gg
- Offspring phenotype: yellow (all)

7. Cross: Gg × gg (Punnett: 2 Gg : 2 gg)
- Yellow pods (gg): 2
- Green pods (Gg): 2

8. Axial (A) dominant to terminal (a). Cross: Aa × aa (Punnett: 2 Aa : 2 aa)
- Axial flowers: 2
- Terminal flowers: 2

Section 3 — Flower color (Purple dominant P, white recessive p)
1. Genotype → Phenotype
- PP → purple
- Pp → purple
- pp → white

2. Cross: PP × pp
- Offspring phenotype: purple (all)

3. Cross: Pp × pp (Punnett: 2 Pp : 2 pp)
- Purple: 2
- White: 2

4. Cross: Pp × Pp (Punnett: 1 PP : 2 Pp : 1 pp)
- Purple: 3
- White: 1

Section 4 — Height (Tall dominant T, short/dwarf recessive t)
5. Genotype → Phenotype
- TT → tall
- Tt → tall
- tt → short (dwarf)

6. Cross: tt × tt
- Offspring phenotype: short/dwarf (all)

7. Cross: Tt × tt (Punnett: 2 Tt : 2 tt)
- Tall: 2
- Short: 2

8. Cross: Tt × Tt (Punnett: 1 TT : 2 Tt : 1 tt)
- Tall: 3
- Short: 1

(Counts above are the usual 4-square Punnett outcomes.)