Mendelian Genetics
Sample word problems
1. In labrador retrievers, black fur
(B) is dominant to yellow fur (b)
Predict the offspring from a cross
between two homozygous black
labs
2. In labrador retrievers, black fur
(B) is dominant to yellow fur (b)
Predict the offspring from a cross
between two homozygous yellow
labs
3. In labrador retrievers, black fur
(B) is dominant to yellow fur (b)
Predict the offspring from a cross
between a heterozygous male
and a yellow female
6. Albinism (a) is recessive
Predict the offspring
of a cross between:
Two heterozygous
pythons
 Two albino pythons
 A homozygous normal
python with an albino
python
 A heterozygous python
with an albino python

7.The rooster has “grizzly” feathers.
The hen has solid color feathers.


This rooster and this
hen have 10 offspring,
all with solid color
feathers.
What does that tell
you about the feather
color trait?
What are the
genotypes of the
rooster, the hen, and
all the offspring?
8. Drosophila melanogaster
The common fruit fly
If a grey fly
mates with a
white fly and
all the
offspring are
grey, which
color is
dominant?
9. Drosophila melanogaster
The common fruit fly
Based on what
you determined
from the last
question, what
would you
predict from a
cross between
two
heterozygous
fruit flies?
10. Drosophila melanogaster
The common fruit fly
Vestigial wings is
a recessive
mutation. What
offspring will
result from a
cross between 2
vestigial winged
flies?
11. In fruit flies, stubble bristles (b)
is a recessive mutation
Predict the
offspring from the
following crosses:
 Two heterozygous
normal flies
 Two stubble bristle
flies
 A heterozygous
normal fly with a
stubble bristle fly
4. Widow’s peak (H) is a dominant
trait
These two
have a baby
with a smooth
hairline.
Determine
their
genotypes and
the genotype
of the baby
5. Widow’s peak (H) is a dominant
trait
Based on what
you know from
the last
question, make
a prediction
about what
might happen if
these two had
kids together
12. Dihybrid Cross – Determine if the genes for
wing shape and eye color are Linked or
Independent
P1
F1
P2
F2
=
=
=
=
Straight wings, Red eyes X Curly wings, Orange eyes
all Straight wings, Red eyes
Straight wings, Red eyes x Straight wings, Red eyes
36 straight wing, red eye
12 straight wing, orange eye
13 curly wing, red eye
4 curly wing, orange eye
13.Which F2 phenotypes (2 correct answers)
would you only expect from Independent
Assortment?
P1
F1
P2
F2
=
=
=
=
Straight wings, Red eyes X Curly wings, Orange eyes
all Straight wings, Red eyes
Straight wings, Red eyes x Straight wings, Red eyes
36 straight wing, red eye
12 straight wing, orange eye
13 curly wing, red eye
4 curly wing, orange eye
14. Dihybrid Cross – Determine if the genes for
eye color and bristles are Linked or Independent
P1
F1
P2
F2
=
=
=
=
red eyes, normal bristles X brown eyes, stubble bristles
all red eye, normal bristle
red eyes, normal bristles X red eyes, normal bristles
28 red eyes, normal bristles
0 red eyes, stubble bristles
0 brown eye, normal bristles
9 brown eye, stubble bristle
15. Are the genes for eye color and bristles on the
same chromosome or on different chromosomes?
P1
F1
P2
F2
=
=
=
=
red eyes, normal bristles X brown eyes, stubble bristles
all red eye, normal bristle
red eyes, normal bristles X red eyes, normal bristles
28 red eyes, normal bristles
0 red eyes, stubble bristles
0 brown eye, normal bristles
9 brown eye, stubble bristle