1. Incomplete Dominance

2. There are exceptions to the dominant-recessive pattern.
Incomplete dominance occurs when two different alleles control a characteristic but neither is dominant.
Instead the different alleles of some genes can be expressed in the heterozygous condition to produce an intermediate phenotype.

3. For example: snapdragon colour

5. R = red; r = white P = red x white (RR x rr) F1: genotype = 100% Rr
F1: phenotype = 100 % pink F1 r R Rr

6. F2: genotype = 25% RR, 50% Rr, 25% rr
F2 = Rr x Rr
F2: genotype = 25% RR, 50% Rr, 25% rr
F2: phenotype = 25% red, 50% pink, 25% white F2 R r RR Rr rr

7. What colour flowers would result from the following crosses?
a) red flower x pink flower
b) white flower x pink flower
c) red flower x white flower
d) pink flower x pink flower

8. Answers:
a) 50% red and 50% pink
b) 50% white and 50% pink
c) 100% pink
d) 25% red, 50% pink, 25% white