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Review Packet for Genetics and Meiosis
Directions: Answer the questions and where indicated, draw a Punnett square and show all work!
1. Who was Gregor Mendel? Where did he live and what did he study in life?
2. What is a gene?
3. Why do scientists study genetics?
4. List Mendel’s three laws.
5. Give an example of a dominant and recessive trait.
6. What is the difference between a genotype and phenotype?
7. What does it mean if something is heterozygous? What does it mean if something is
homozygous?
8. Compare and contrast mitosis and meiosis.
9. Draw a cell with four chromosomes undergoing meiosis. Label all stages.
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10. What stage of meiosis are these cells in?
11. How many chromosomes are in a somatic human cell? How many chromosomes are in a
human gamete?
12. What is the difference between a haploid cell and a diploid cell?
13. Define “homologous chromosomes” and draw a picture.
14. Complete the table and then answer the following questions.
Organism
Tomatoes
Cat
Wheat
2n
n
12
38
a) What is the diploid number for wheat?
b) How many chromosomes are in a cat gamete?
c) What is the haploid number of chromosomes for a tomato?
21
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15. PKU stands for phenylketonuria, which is the inability to recognize and process the amino acid
phenylalanine. PKU is an inherited disease caused by a recessive gene. If a mother and father
are both carriers for the disease:
 What is the probability of producing a child with PKU? ______________
 What is the probability of producing a child that has the gene and can pass it on (a
carrier/no disease) ? ___________________________________
16. Green (G) is dominant in peas. Yellow (g) is recessive. What are the genotypes of the P1
generation if the F1 generation is about 75% green and 25% yellow? ___________________
Draw the square.
17. Polydactly (extra digits) is a dominant trait. Anne Boleyn, the second wife of Henry VIII , had 11
fingers. Henry VIII had the usual number. Anne and Henry only had one child, Elizabeth I, who
had the normal number of fingers.
 What is Ann Boleyn’s genotype?________________________
 Did one of her parents have to have extra digits? _____________
 What is the probability that Anne and Henry would have a child with extra
digits?_____________________
18. If both parents have heterozygous Type A blood, what is the percent chance that they will
produce a child with Type O blood? ____________ (Draw the square and write blood type in
each square).
19. If both parents have Type AB blood, what are the possible blood types for their children. Draw
the Square.
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20. If the mother is heterozygous Type B and has three children with Type A, Type O, and Type AB,
what is the father’s blood type? Draw the square.
21.
(Note: Show your math and or punnett square - neatly - so you can
partial credit if you make an error!) Cleft chin and Unibrow are both single gene traits with
clear dominant-recessive inheritance. Unibrows and cleft chins are both dominant. If a mother
who is heterozygous for cleft chin and has no unibrow has a child with a man who has no cleft
chin and is homozygous dominant for unibrow, what is the probability that they will:
have a child with a cleft chin and a unibrow?_________________
have a child with no cleft chin and no unibrow? ______________
have a child with no cleft chin and a unibrow? ________________
22. (Note: Show your math and or punnett square - neatly - so you can partial credit if you make
an error!) Curly hair shows incomplete dominance over straight hair, and attached earlobes is
dominant to unattched earlobes. If a wavy-haired, homozygous for attached earlobe mother
has a child with a straight-haired, unattached earlobe father, what is the probability that they
will have:
a wavy-haired child with attached earlobes?___________________________
a straight-haired child with unattached earlobes? ___________________
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23. Marfan syndrome is an inherited condition that affects the connective tissue, resulting in
unusually long bones and spinal curvature, as well as vision, cardiac, and respiratory problems.
The syndrome tends to become increasingly severe over time. The following pedigree shows
inheritance of Marfan syndrome in a multigenerational family.
a) How is this syndrome inherited?
b) Can you determine individual II4’s genotype? Explain.
c) Individual II1 and II2 are considering having another child. What is the probability that this
child will have Marfan syndrome? Explain using a Punnett square.
24. In the pedigree below, different blood types are identified by the letters A, B, AB, and O.
a) Individuals II4 and II5 have just had identical twin girls. List the possible blood types these
infants may have based on the information provided in the pedigree.
b) Individuals II6 and II7 have a second child with blood type O. What does this tell you about
II6’s genotype?
c) Could I1 and I2 have a child with the AB blood type? Explain why or why not.
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25. Duchenne Muscular Distrophy (DMD) is a sex-linked disease that is found on the X
chromosome. Using a Punnett square, show the probability of:
a. Having an affected son if the mother is a carrier and the father is normal
b. Having an affected daughter if the mother is a carrier and the father is normal
26. What is the difference between incomplete dominance and co-dominance? Provide an
example of each.
27. Name and give an example of the effects of one of the four abnormal sex chromosome
disorders (XXY, XYY, X0, XXX).
28. What is non-disjunction? When can it occur?
29. What is a karyotype?
30. What is a Barr body?
31. Characterize cystic fibrosis, hemophilia, Huntington’s disease, Duchenne muscular dystrophy,
Tay Sach’s, and Sickle Cell as either autosomal or sex linked diseases. List the symptoms of at
least two of these diseases.
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32. The ratio 9:3:3:1 is a “classic” (unchanging!) ratio for what kind of cross in Mendelian genetics?
a. homozygous- heterozygous cross
b. heterozygous dihybrid cross
c. a pure-breeding dominant-recessive cross
d. a pure-breeding recessive cross
33. The failure of chromosomes to separate during meiosis is called
a. Nondisjunction
b. X-chromosome inactivation
c. Turner’s syndrome
d. Down syndrome
34. Normal human females produce egg cells that have
a. One X chromosome
b. Two X chromosome
c. One X and one Y chromosome
d. One X or one Y chromosome
35. What is the approximate probability that a human offspring will be male?
a. 25%
b. 40%
c. 50%
d. 60%
36. Which of the following are shown in a karyotype?
a. Homologous chromosomes
b. Sex chromosomes
c. Autosomes
d. All of the above