Name ________________________
Hour _______
7th Grade Science Worksheet
Punnett Squares
Identify the following as genotypes or phenotypes. If it is a genotype, identify if it is
homozygous dominant, homozygous recessive, or heterozygous.
1. GG
2. Bb
3. Blue eyes
4. tt
5. Yellow seeds
6. Pink flowers
7. Zz
8. Yellow coat color
9. Ability to roll tongue
10. pp
11. In flowers, red flowers (F) are dominant to white flowers (f). In a cross of a red
flowered heterozygous plant and a white flowered homozygous recessive plant,
what would the possible genotypic ratio of the offspring? What percentage of the
offspring are homozygous dominant? What percentage of the offspring are
heterozygous? What percentage of the offspring are homozygous recessive?
12. In dogs, wire hair (H) is dominant to smooth (h). In a cross of a homozygous
dominant wire-haired dog with a homozygous recessive smooth-haired dog, what
will be the possible phenotypes of the offspring? What will be possible
genotypes?
13. In pea plants, spherical seeds (D) are dominant to dented seeds (d). In a genetic
cross of two plants that are heterozygous for the seed shape trait, what percentage
of the offspring should have spherical seeds?
14. Red flowers (R) are dominant to white flowers (r) in snapdragons. What would
the genotypic ratio be if you crossed a homozygous red flower snapdragon with a
heterozygous red flower snapdragon?