Name __________________________
Period ________ Date ____________
Outcome Score
5.3
5.4
6.1
Phenotype and Genotype (492 – 495)
Read the essay and answer the following questions. Define the terms.
1. List 2 phenotypes mentioned in the essay.
2. What provides the blueprint for the offspring’s phenotype?
3. What does this mean for the phenotypes of the offspring?
4. Other than genes, what can influence an organism’s phenotype? Give an example.
5. What are two examples of complex phenotypes that involve genetic and environmental
factors?
6. Briefly describe the experiment done by scientists and the results of the experiment to test
the hypothesis: “Environmental factors influence how genetic information produces a
phenotype.”
7. Explain how genotype influences phenotype (look at the example about the cleft chin).
8. How does independent assortment affect inheritance?
Define the following terms.
Phenotype –
Genotype –
Chromosomes –
Gene –
Allele –
Heterozygous –
Homozygous –
Dominant trait –
Recessive trait –
Independent assortment –
Name __________________________
Period ________ Date ____________
Outcome Score
5.3
5.4
6.1
Monohybrid Cross Homework Problems
Answer the following questions on a separate sheet of paper.
1. Make a list of the seven pairs of contrasting traits Mendel found garden peas to have. State
which is dominant and which is recessive.
2. The gene for black coat color is dominant in guinea pigs. How is homozygous black
different from heterozygous black, even though the guinea pigs look alike?
3. When two hybrid animals are crossed, there appear among the offspring homozygous
dominant, heterozygous and homozygous recessive individuals. Explain.
4. When two parents that are heterozygous for one trait are crossed, what ratio of offspring (F1
generation) is expected to show the dominant trait and what ratio are expected to show the
recessive trait.
5. In guinea pigs, black coat color is dominant over white coat color. What type of offspring
could result from a cross between a homozygous black guinea pig and a heterozygous black
guinea pig? Use a Punnett Square to obtain your results. Include genotype and phenotype
ratios.
6. A pea plant, homozygous for yellow seeds, was crossed with a pea plant homozygous for
green seeds. What is the genotype and phenotype of the F1 and F2 generations?
7. In fruit flies, normal wings are dominant over vestigial wings. What type of offspring could
result from a cross involving a homozygous normal-winged fruit fly and a vestigial-winged
fruit fly? Give the genotype and phenotype ratios.
8. The gene for purple flowers is dominant over the gene for white flowers. What type of
offspring would result from a cross of a purple (homozygous) flowered plant with one
producing white flowers? Give the genotype and phenotype ratios.
9. Mendel crossed a purebred smooth pea, which is dominant, with a purebred wrinkled pea.
Give the results of the F1 and F2 generations. Give the genotype and phenotype ratios.
10. Mendel crossed a hybrid tall pea plant with a hybrid tall pea plant. Give the results of their
offspring. Give the genotype and phenotype ratios.
Name __________________________
Period ________ Date ____________
Outcome Score
5.3
5.4
6.1
Dihybrid Cross Homework Problems
Answer the following questions on a separate sheet of paper.
1. A right-handed, blue-eyed man marries a right-handed, brown-eyed woman. They have two children,
one left-handed and brown-eyed and the other right-handed and blue-eyed. By a later marriage with
another woman, who is also right-handed and brown-eyed, this man has nine children all of whom
are right-handed and brown-eyed. What are the genotypes of this man and his two wives?
2. A brown-eyed, right-handed man marries a blue-eyed, right-handed woman. Their first child is blueeyed and left-handed. If other children are born to this couple, in what combinations and
proportions will their appearance be as to these two traits?
3. In horses, black is due to a dominant gene B, chestnut to its recessive allele b. The trotting gait is
due to a dominant gene T, pacing to its recessive allele t. A homozygous black trotter is crossed with
a chestnut pacer. What sort of foals will result in several crosses of this type? Give the genotype and
phenotype ratios.
4. Some dogs bark when trailing, others are silent. The barking trait is due to a dominant gene. Erect
ears are dominant to drooping ears. What kind of pups would be expected from a cross involving a
heterozygous erect-eared barker mated to a droop-eared silent trailer? Give the genotype and
phenotype ratios.
5. A farmer crossed pea plants that produce green seeds and were short with plants that were pure for
yellow seeds and tallness. What types of offspring would result from the cross? (Remember: tall is
dominant and so is yellow!)
6. In guinea pigs, black coat color and short hair are both due to dominant genes. What type of
offspring would result from a cross involving two heterozygous black, shorthaired guinea pigs?
(NOTE: long hair and white coat color are recessive.)
7. In tomatoes, red fruit is dominant over yellow and tall vines are dominant over short vines. A
tomato breeder has pure races of yellow-fruited tall plants and red-fruited short plants. He wants a
pure race of red-fruited tall plants. If he crosses the two races, what phenotypes does he have in the
F1?
8. A freckled- blue-eyed man married a brown-eyed woman without freckles. What are the possibilities
for their offspring? (NOTE: the man is heterozygous for freckles and the woman’s mother had blue
eyes.)
9. A pure line black, curly rabbit was mated with a pure line white, straight-haired rabbit. Black hair and
curly are dominant. Give the F1 and F2 generations of offspring with ratios.
10. A right-handed, blue-eyed man whose father was left-handed marries a left-handed, brown-eyes
woman from a family in which all the members have been brown-eyed for several generations. What
offspring may be expected from this marriage as to these traits?