Download Incomplete Dominance and Co

 Is
the purple plant
homozygous or
heterozygous ?
 Perform
 Always!
a test cross!
Cross the
unknown with a
homozygous recessive
Test Cross
? x gg
P
g
g
Key:
G=green
g= yellow
G g
Gg
F1
G g
Phenotype:
100% green
Gg
Genotype:
100% heterozygous
P
? x gg
Key:
G=green
g= yellow
F1
Phenotype:
50% green
50% yellow
Genotype:
 Neither
allele is dominant
 In some cases, an intermediate phenotype is
shown
 In
snapdragons, flower color can be red,
pink, or white. The heterozygous condition
results in pink flowers
rr
RR
Rr
Key:
R= Red
r= White
F1 Phenotype:
100% pink
F1 Genotype:
100% heterozygous Rr
Key:
R= Red
r= White
Phenotype: 1:2:1
25% Red
25% White
50% Pink
Genotype: 1:2:1
25% homozygous RR
25% homozygous rr
50% heterozygous Rr
 Both
alleles are expressed equally
 Neither allele is more dominant than the
other
Erminette
chickens
Roan Cows
Key:
B =Black
B1 = White
B
B
B1
B
B1
B B1
B1
B B1
B
B1
P generation
 Black chicken X White chicken


F1 generation = erminette
(checkered patterned)
Phenotype: 4:0 or 1:0
100% erminette
Genotype: 4:0 or 1:0
100% heterozygous
Key:
BB =Black
BW = White
Key:
B= Black
W= White
BB
B1
B2
B1
B 1 B1
B1 B2
B2
B 1 B2
B2 B2
BW
BB
BB BB
BB BW
BW
BB BW
BW BW
Key:
B1 =Black
B2 = White