Download Genetics Review Questions

Genetics Review Questions
1. Use the words in the following list to complete each sentence. Each word
is used only once.
Gene, dominant, recessive, phenotype, genotype, gamete, meiosis, X
chromosome, Y chromosome, mitosis
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
A __________ is a unit of DNA inherited by an organism.
A __________ allele is masked if it is paired with a dominant allele.
A __________ is the gene combination for a single characteristic.
Of the two sex chromosomes, the __________ has fewer genes.
A female has two __________.
A trait that shows in an organism is its __________.
A __________ allele is always expressed.
During ________, cells are formed with one set of unpaired chromosomes.
A sex cell is called a __________.
__________ results in two cells being produced which are identical to the
parent cell.
2. Horses have 32 pairs of chromosomes in their body cells. How many
chromosomes are in their gametes?
3. Your cells contain 23 pairs of chromosomes, how many chromosomes is
this?
4. How is it possible for a person to carry a genetic disorder?
5. When identical twins are born they contain a identical genetic information
for their future growth and development. Explain why such twins reared
apart often end up different.
6. If the allele for round seeds in peas (R) is dominant, and the allele for
wrinkled (r) is recessive, what would be the phenotype of the following
genotypes? RR, Rr, rr?
7. Your sister is pregnant and is convinced that the baby will be a girl
because girls run in the family. How would you convince her that there is
an equal chance that the baby will be a girl or a boy?
8. A man and a woman both have brown eyes. They produce a blue eyed
child. Explain how this could happen.
9. Here are some statements about cell division. Arrange them in two lists
based on the type of cell division they best apply to.
-
Produces two identical daughter cells.
Produces four haploid cells
Homologous chromosomes pair off.
Produces clones of the parent cell.
Takes place in all cells
Takes place in gamete producing cells.
10. Explain the difference between a dominant and a recessive characteristic.
11. Every business has an office. Inside the office is a filing cabinet and inside
the cabinet are files. Inside each file there is specific information. Compare
this to a cell. Which part is equivalent to the office, the filing cabinet, the
files and the specific information in the files?
12. A man who is homozygous for brown eyes marries a woman who is blue
eyed. Predict the eye colour of their children, if brown eyes are dominant
to blue.
13. What gender will a person be if they have two X chromosomes and a Y
chromosome.
14. Two heterozygotes for a particular characteristic are crossed. What is the
chance that their offspring will be homozygous recessive? Heterozygous?
15. Four babies were mixed up at the hospital. Each baby had a different
blood group, O, A, B and AB. The four pairs of parents had the following
blood groups O and O, AB and O, B and B, A and B. Which child belonged
to which parents?
16. Phenylketonuria (PKU) is inherited as an autosomal recessive trait.
Children born with this disorder will suffer mental and physical disabilities
unless they are placed on a special diet from birth. John and Betty were
both normal and they have three children, Thomas (who has the disease),
David and Margaret (who are both normal).
a. Show this information on a pedigree
b. What are the genotypes of John and Betty?
c. What is the chance that another child in this family will have PKU?
d. What is the chance that David is heterozygous? Explain
e. Thomas was placed on the special diet and so developed normally. He
marries Sally, who is normal but who has a PKU parent. What is the
chance of PKU among their offspring?
f. If one of Sally and Thomas’ children does not have PKU, can they pass
it on to their offspring?
17. A fly has 8 chromosomes in its normal body cells. Predict how many
chromosomes there are in the following: a) a fly sperm cell, b) a fly diploid
cell, c) a fly zygote
18. Red-Green Colourblindness is a sex linked recessive condition. A woman
with normal vision who had a colourblind father marries a colourblind man.
a. What are the genotypes of the woman and her husband?
b. What are their possible offspring?
c. They have a son, what is the chance that he is colourblind?
d. What is the chance that their next child will be a colourblind daughter?
19. Red and white flower colour is an example of incomplete dominance. The
result of a cross between a red flower and a white flower is a pink flower.
a. Predict the outcome of a cross between a red flower and a pink flower.
b. Pink flowers are crossed and 1000 seeds are produced. Predict how
many of these seeds would be expected to grow into pink flowers.
20. Consider the following pedigree
a. Is this a recessive or a dominant condition? Explain
b. Place a cross on person II – 4
c. Is this an autosomal or sex linked condition? Explain
d. Assign a genotype to all individuals in the pedigree.
21. In fruit flies, the gene for red eye colour is dominant to that for white. The
gene for eye colour is located on the X chromosome. On the following
pedigree write the sex and phenotype of each individual
XRXr
XrXr
XrY
XrY
XRXr
XRY
22. X-Rays can be mutagenic. Why are the lower abdominal regions of a
person covered with lead when they have an x-ray? Explain in detail.