Genetics Review
Name: ________________
Hr: ____
Genetics Objectives
1. Explain how probability is used in genetics.
2. Be able to complete a punnett square accurately and use it to predict the offspring
between two parents.
3. Predict and understand the results of a cross between two parents in the following three
circumstances: blood typing, sex linked traits, and incomplete dominance.
4. Identify gender, chromosome disorders, and possible non-disjunction of a person by reading
a karyotype.
5. Create an accurate pedigree showing a trait through several generations of families.
6. Students will use decision making skills to analyze and evaluate a real life genetic problem.
Define the following terms:
1. genetics
2. hybrid
3. gene
4. allele
5. dominant
6. recessive
7. probability
8. homozygous
9. heterozygous
10. phenotype
11. genotype
12. F1 or F2
Be able to correctly complete the following crosses using the four step method.
Monohybrid: (dominant/recessive)
13. Having red hair (H) is a dominant gene. What is the probability that the children, of
someone who is a homozygous for red hair with and a person who does not have read
hair, will have red hair? (Show all four steps)
14. In humans a straight thumb in dominant to a curved thumb. Fred has a curved thumb and
marries Edna, who has a straight thumb and is heterozygous for the trait. What is the
probability of Fred and Edna having children with curved thumbs? Show all four steps.
Incomplete dominance: (3 choices)
15. In Andalusian birds, there are three colors of feathers that are possible. Black (BB), White
(WW), and blue (BW). What is the expected outcome of a black and a blue bird? (Show
all four steps)
16. Carnation flowers are either colored (red) or lack coloring, and are white. The coloring in
carnations is an example of incomplete dominance. A scientist wanted to produce a new color
of carnation. She took a red carnation and crossed it with a non-colored (white) carnation.
Show the offspring produced from this cross. Show all four steps.
Blood Typing:
What are the four possible blood types and the genotypes for each?
17. Bill and Anne are pregnant with their first child. They are curious as to which blood type
their child will have. Bill has type O blood and Anne has type B blood. What are the possible
blood types their child can have? Show all four steps.
18. Last week on Maury Povich, Betty with A blood type claimed that Bill, who has O blood type
was the father of her baby. The baby has AB blood type. Is it possible for Bill to be the
father? Support your answer with a punnett square.
Sex-linked: (male = XY & Female = XX)
19. In a cross between a white-eyed female fruit fly and red-eyed male, what percent of the
female offspring will have white eyes? (White eyes are sex-linked recessive). Show all four
steps.
20. Duchenne muscular dystrophy is a sex-linked recessive disorder that results in the
progressive weakening and loss of skeletal muscle. A young couple is worried about their
family’s history of this disorder and would like to know their chances of having children with
muscular dystrophy. What would you tell them if the woman is heterozygous for the
disorder and the man does not have it? List the genotype for both parents and explain your
findings. Show all four steps.
21. What is a karyotype?
22. What information can we get from a karyotype?
23. What causes non-disjunction (missing or extra chromosomes)?
24. You will need to know how to create and read a pedigree. Create a pedigree showing two
people having four children, the youngest being male and the rest being female. The
oldest child is married and has three children all girls. Correctly identify that persons
I-2, II-3 have a hitch hiker’s thumb.