2. Ever wonder what the chances are to inherit
TWO different traits at once?
For instance, what is the likelihood of a
person having blonde hair and blue eyes?
Or what kind of puppies can my
tan, curly tailed pug have?
3. 1. When presented with a problem, first read
the information. Then list the traits:
In horses, black color depends on a dominant gene (B) and
chestnut color is recessive (b). The trotting gait is due to a
dominant gene (T) and the pacing gait (t) is recessive. Cross
a homozygous black pacer with a chestnut heterozygous
trotter.
Black = Trotting =
Chestnut = Pacing =
4. 2. Then determine the genotypes of the
parents:
In horses, black color depends on a dominant gene
(B) and chestnut color is recessive (b). The trotting
gait is due to a dominant gene (T) and the pacing
gait (t) is recessive. Cross a homozygous black
pacer with a chestnut heterozygous trotter.
__________ X __________
5. 3. Then, determine the gametes each parent
can produce. You will use the FOIL method.
Each gamete should have one of each allele.
BBtt X bbTt
6. 4. Now, determine the offspring by filling in
the grid. Keep like letters together, and
always write the dominant allele first
Bt Bt Bt Bt
bT BbTt
bt
bT
bt
7. 5. Finally, use the Punnett Square to answer the
questions about genotype and phenotype
probabilities.
Bt Bt Bt Bt
bT BbTt BbTt BbTt BbTt
bt Bbtt Bbtt Bbtt Bbtt
bT BbTt BbTt BbTt BbTt
bt Bbtt Bbtt Bbtt Bbtt
8. Genes for different traits can segregate
independently during the formation of
gametes.
RrYy
Ry rY
ry
RY
9. He found
◦ Round Yellow
◦ Round green
◦ wrinkled Yellow and
◦ wrinkled green peas.
This means that the Round allele can be
inherited separately from the Yellow allele.
