Tongue rolling allele is dominant (R)
Non tongue rolling allele is recessive (r)
Both parents are both heterozygous for the
tongue rolling gene.
What is the probability that:
a) their firstborn child is a non tongue roller?
b) the second child is also a non tongue roller?
c) the third child is a tongue roller?
Mother = Rr
Father = Rr
Mother
Father
R
r
R
RR
Rr
r
Rr
rr
Farmer Ted has a curly
tailed male pig and wants
to know whether it is pure
breeding or not. He has
asked you to find out for
him. He pays you $400.
Curly tails (T) are dominant
over straight tails (t).
Write your answer on your book
Pure Breeding
Male = TT
Female = tt
Male
Female
T
T
t
Tt
Tt
t
Tt
Tt
NOT Pure Breeding
Male = Tt
Female = tt
Male
Female
T
t
t
Tt
tt
t
Tt
tt
Punnett Squares are used to determine
the probability of an offspring having a
particular genotype.
Test Cross & Pure Breeding
Pure Breeding = Homozygous Genotype
In genetics a test cross is used to
determine if an individual exhibiting a
dominant trait is homozygous or
heterozygous (i.e. pure breeding or not)