Dihybrid Practice
Name
In rabbits, grey fur (G) is dominant to white fur (g) and black eyes (B) are dominant to red eyes (b).
1. What are the phenotypes of rabbits that have the following genotypes?
Ggbb
ggBB
ggbb
GgBb
2. What are the possible gametes for a homozygous grey furred and homozygous black eyed rabbit?
(HINT: Use the FOIL technique!)
Parent Genotype: GGBB
Gametes:
3. What are the possible gametes for a heterozygous grey furred and heterozygous black eyed rabbit?
Parent Genotype: GgBb
Gametes:
4. What are the possible gametes for a heterozygous grey furred and red eyed rabbit?
Parent Genotype:
Gametes:
5. What are the possible gametes for a white furred and heterozygous black eyed rabbit?
Parent Genotype:
6.
A male rabbit with the genotype Ggbb is crossed with a female rabbit with the genotype ggBb.
The dihybrid Punnett square is set up below. Complete it to answer the questions that follow.
Gb
gB
Gametes:
Gb
gb
gb
b
a)How many out of 16 have grey fur and black eyes?
b)How many out of 16 have grey fur and red eyes?
c)How many out of 16 have white fur and black eyes?
gB
d)How many out of 16 have white fur and red eyes?
gb
gb
e) What is the phenotypic ratio for this cross?
7. Show the cross between a heterozygous grey haired and heterozygous black eyed male (GgBb) with a white
haired and red eyed female (ggbb).
a)How many have grey fur and black eyes?
b)How many have grey fur and red eyes?
c)How many have white fur and black eyes?
d)How many have white fur and red eyes?
e) What is the phenotypic ratio for this cross?
In humans, freckles (F) are dominant to no freckles (f). Also, hairy toes (T) are dominant to non-hairy toes (t).
8. Cross a homozygous freckled, heterozygous hairy toed male with a non-freckled and homozygous hairy toed female.
What is the phenotypic ratio for this cross?
9. Cross a freckled and hairy toed male (whose mother had no freckles and non-hairy toes) with a freckled
and hairy toed female (whose father had no freckles and non-hairy toes).
What is the phenotypic ratio for this cross?