32. A cross between homozygous dominant
genes and homozygous recessive
genes will result in a progeny of
heterozygous genes determining all
dominant traits.
LAW OF COMPLETE
DOMINANCE
34. In fruit flies, gray is dominant over
black. If pure-bred gray fruit fly
crosses with a black fruit fly, what
percent of the offspring will be gray?
SAMPLE PROBLEM SET 1
38. 1. In dogs, there is a hereditary type of deafness
caused by a recessive gene. Two dogs who
carry the gene for deafness but have normal
hearing are mated. What are the possible
genotypes and phenotypes of their offspring and
the percent chance for each?
PROBLEM-SOLVING
39. 2. In guinea pigs, short hair (S) is dominant over
long hair (s). If a homozygous short haired
guinea pig is crossed with a long haired guinea
pig, what are the possible genotypes and
phenotypes of their offspring and the percent
chance of each?
PROBLEM-SOLVING
40. 3. Suppose that black hair (H) is dominant
over blonde hair (h) and brown eyes (E) are
dominant over blue eyes (e). The father has
heterozygous black hair and heterozygous
brown eyes and the mother has blonde hair
and blue eyes.
PROBLEM-SOLVING
41. SEATWORK
1. Imagine that you are a rabbit breeder with
two purebred rabbits, a male with black fur and
a female with tan fur. When you cross your
rabbits, all of the F1 (baby rabbits) have tan fur.
Which trait is dominant, and which is
recessive?
42. 2. In fruit flies, gray is dominant over
black. If the offspring’s genotypic ratio
is 2 Gg: 2 GG, what are the
genotypes of the parents of the baby
fruit flies?
SEATWORK
43. 3. ACyclops that is resistant to pesticides and
has smooth antennae is crossed with on that
is heterozygous for both traits.
a. Show the genotypes of theparents.
b. Set upa Punnett square for the cross
c. Show the genotype and phenotype of the
offspring.
SEATWORK
45. 1. The gene that is always expressed
2. Two genes that determines certain traits are
alike
3. The actual genetic make up of an organism
4. An organism that receives different genetic
information for a trait from each parent
5. Cross which considers the inheritance of two
traits at a time
IDENTIFICATION
46. Yellow fruit and dwarf vines are recessive traits in tomatoes.
Red fruit and tall vines are dominant. Complete a Punnett
square and answer the questions for a completely dominant
red and tall plant crossed with a heterozygous red and
homozygous dwarf plant.
6. What percent of the offspring will be totally heterozygous?
7. What is the phenotype ratio of the offspring?
8. What percent of the offspring will have yellow fruit and
dwarf vines?
PROBLEM-SOLVING
47. In rabbits, gray hair is dominant to white hair. Also in rabbits,
black eyes are dominant to red eyes. These letters
represent the genotypes of the rabbits:
9. What are the phenotypes of rabbits that have the following
genotypes? Ggbb, ggBB, ggbb, and GgBb
PROBLEM-SOLVING
GG= gray hair BB= black eye
Gg= gray hair Bb= black eye
gg= white hair bb= red eye
48. 10. A male rabbit with the genotype
GGbb is crossed with a female rabbit
with the genotype ggBb. Complete a
Punnett square and determine the
genotype and phenotype proportions
in the offspring.
PROBLEM-SOLVING
49. 11. In chicken, black is dominant over
white. If the percentage of the offspring’s
phenotype is 75% black and 25% white,
what are the possible genotypes of the
parents? Show a Punnett square to prove
your answer.
PROBLEM-SOLVING
