Punnet practice answers
To go along with your inheritance
practice worksheet
Simple inheritance:
H = Hairy
h = Bald
B = Purple skin
b = Green skin
R = Ridged tail
r = Smooth tail
Hh x hh
H
h
Hh
h
hh
A heterozygous hairy newt is mated
with a bald newt. What percentage
of their offspring will have hair?
•Identify parent genotypes.
•Determine potential gametes.
h
Hh
hh
50% of the offspring will
have hair
•Combine potential gametes
•Answer the question
Simple inheritance:
H = Hairy
h = Bald
B = Purple skin
b = Green skin
R = Ridged tail
r = Smooth tail
bb x BB
b
B
Bb
b
Bb
A green skinned newt is mated with
a homozygous purple skinned new.
What percentage of their offspring
will be green?
•Identify parent genotypes.
•Determine potential gametes.
B
Bb
Bb
•Combine potential gametes
0% of the offspring will
be green
•Answer the question
Simple inheritance:
H = Hairy
h = Bald
B = Purple skin
b = Green skin
R_ x R_
R
R
RR
?
R_
R = Ridged tail
r = Smooth tail
Two ridged tailed newts are mated and
some of their offspring have smooth tails.
What can you deduce about the genotype
of the parents based on the phenotype of
the offspring?
•Identify parent genotypes.
•Determine potential gametes.
?
R_
rr
•Combine potential gametes
Parents are heterozygous
•Answer the question
Simple inheritance:
H = Hairy
h = Bald
B = Purple skin
b = Green skin
R = Ridged tail
r = Smooth tail
BbRR x bbrr
BR
bR
BR
bR
br
BbRr
bbRr
BbRr
bbRr
br
BbRr
bbRr
BbRr
bbRr
A newt breeder from eastern Pennsylvania
needs your help. She has a heterozygous
purple skinned newt with a ridged tail
(homozygous dominant). She crosses that
newt with a green skinned newt with a
smooth tail.
•Identify parent genotypes.
br
BbRr
bbRr
BbRr
bbRr
•Determine potential gametes.
br
BbRr
bbRr
BbRr
bbRr
% with purple skin = 50%
•Combine potential gametes
% wih smooth tail = 0%
% with green skin and ridged tail =50%
•Answer the question
Incomplete dominance:
RR = Red
WW = White
RR x WW
R
W
W
RW
RW
R
RW
RW
RW = Pink
You are a florist with a small supply of
red, white, and pink carnations. You’ve
just receive a large order for pink
carnations. Knowing that carnation
coloring is an example of incomplete
dominance what should you do to
increase your supply of pink carnations?
•Identify parent genotypes.
•Determine potential gametes.
•Combine potential gametes
A cross between red flowers and
white flowers will produce all pink
flowers
•Answer the question
Co-dominance:
RR = Red
WW = White
RW = Roan
(Red and white hairs)
A white cow is mated with a roan bull.
WW x RW
•Identify parent genotypes.
W
W
•Determine potential gametes.
R
W
RW
WW
RW
WW
•Combine potential gametes
•Answer the question
What percentage of the offspring will be Red? 0%
What percentage of the offspring will be White? 50%
What percentage of the offspring will be Roan? 50%
Sex-linked inheritance: (remember, females = XX males = XY)
XR = Normal
Xr = Color blind
If a heterozygous female is mated with a
color blind male what percentage of the
offspring will be male?
What percentage of the of males will be
color blind?
XRXr x XrY
XR
Xr
•Identify parent genotypes.
Xr
Y
XRXr
XrXr
•Determine potential gametes.
XRY
Xry
50% of the offspring will be male
50% of the males will be color blind
•Combine potential gametes
•Answer the question