Download Genetics Problems

Genetics Problems
Name
Period
Date
1. Circle those gene sets that are alleles of each other. Double circle those sets of genes that are homozygous
alleles of each other.
Aa
BB
CD
EE
Me
Ff
gg
HI
Jj
ZS
Ll
Gb
Mm
aA
LL
Oo
OQ
Tt
2. In the moth, black color is dominant over white. If a pure bred black moth is crossed (Mates) with a pure
white moth, write the genotypes and phenotypes for the following generations.
P Phenotypes | Genotypes
F-2 Phenotypes
F-1 Phenotypes
F-2 Genotypes
F-1 Genotypes
3. A homozygous wrinkled pea plant is crossed with a homozygous round pea plant. The round peas are
dominant over the wrinkled peas. Write out the genotypes and phenotypes for the P-1, F-1 and F-2 generation
of plants. (as you did above) .
P Phenotypes | Genotypes
F-2 Phenotypes
F-1 Phenotypes
F-2 Genotypes
F-1 Genotypes
4. A rose bush with terminal flowers (flowers on the end of the branch) is crossed with a homozygous rose
bush with axial flowers (flowers on the sides of the branches). Axial flowers are dominant over terminal
flowers. Write out the genotypes and phenotypes for the P-1, F-1 and F-2 generations of rose bush plants.
P Phenotypes | Genotypes
F-2 Phenotypes
F-1 Phenotypes
F-2 Genotypes
F-1 Genotypes
5. A heterozygous tall plant is crossed with a short plant. Tall is dominant over short. Write out the genotypes
and phenotypes for the P-1 and F-1 generation. If you were to write out the F-2 generation, what problem
would exist?
P Phenotypes | Genotypes
F-1 Phenotypes
F-1 Genotypes
6. In the cross of monohybrids, if in the F-2 generation you have a 3:1 ratio in the phenotypes, what type of
genotypes did you have in the P-1 generation?
7. In roses, when a red flowering plant is crossed with a white flowering plant, they produce a pink flower.
Cross a homozygous red plant with a homozygous white plant and give the following information.
P Phenotypes | Genotypes
F-2 Phenotypes
F-1 Phenotypes
F-2 Genotypes
F-1 Genotypes
8. Among dogs, long hair is not dominant over short hair. Instead you get one with a medium length hair.
Cross a long haired dog with a short haired dog and give the following information.
P Phenotypes | Genotypes
F-2 Phenotypes
F-1 Phenotypes
F-2 Genotypes
F-1 Genotypes
9. In a field of flowers it is observed that there are three colors of flowers, dark green, light green and white.
There are twice as many light green flowers as there are either dark green or white. Give the information below
that would result in this ratio or result (think backwards).
P Phenotypes | Genotypes
F-2 Phenotypes
F-1 Phenotypes
F-2 Genotypes
F-1 Genotypes
10. Among hamsters curly hair is a dominant expression over straight hair. Cross a homozygous hamster for
straight hair with a homozygous hamster for curly hair. Give the genotypes and phenotypes and the ratios of
occurrence for each of the P-1, F-1 and F-2 generations.
P Phenotypes | Genotypes
F-2 Phenotypes
F-1 Phenotypes
F-2 Genotypes
F-1 Genotypes
11. In rose bushes, the presence of leaves with serrated (cut) edges is dominant over those bushes that have
rounded edged leaves. Cross a homozygous serrated bush with a homozygous for rounded edges. Determine
the genotypes, phenotypes, and ratios of occurrence in the P-1, F-1 and F-2 generations.
P Phenotypes | Genotypes
F-2 Phenotypes
F-1 Phenotypes
F-2 Genotypes
F-1 Genotypes
Genetics Problems
2
12. Among chickens it is found that red feathers are dominant over white feathers. Make the following cross
and accurately fill in the information asked for. Cross a homozygous red rooster with a pure bred white hen.
P Phenotypes | Genotypes
F-2 Phenotypes
F-1 Phenotypes
F-2 Genotypes
F-1 Genotypes
13. In humans the presence of extra fingers is a dominate trait, however because of the small number of people
with this gene it is only occasionally seen. Cross a heterozygous male with a heterozygous female for this trait.
Describe or identify the genotypes and phenotypes for the P-1 and F-1 generations.
P Phenotypes | Genotypes
F-1 Phenotypes
F-1 Genotypes
14. Orange flowers are dominate over blue flowers. Cross a heterozygous orange flowered plant with a blue
flowered plant and identify the genotypes and phenotypes.
P Phenotypes | Genotypes
F-1 Phenotypes
F-1 Genotypes
15. Among hamsters curly hair is a dominant expression over straight hair and black fur is dominant over white
fur. Cross a hamster that is heterozygous for both curly hair and black fur with another hamster that is also
heterozygous for curly hair and black fur.
P Genotypes
F-1 Phenotypes
Challenge Question:
A newly discovered sea creature was found to have multiple alleles for shell color. Red (Sr) shell color is
dominant to yellow (Sy) and green (Sg). Yellow is dominant to green. List all the phenotypes and all their
possible genotypes.
Genetics Problems
3