Name: 
 

Unit III: Genetics REVIEW


Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 
What is chemotherapy?
a.
the use of drugs to treat a disease
b.
the use of surgery to treat a disease
c.
the use of radiation to treat a disease
d.
the use of drugs to prevent cancer from occurring
 

 2. 
Which is one advantage of sexual reproduction?
a.
More offspring are produced.
b.
More offspring survive to maturity.
c.
The offspring have more genetic variation.
d.
The offspring and the parents are identical.
 

 3. 
The joining of an egg cell and a sperm cell is called
a.
gestation.
b.
adaptation.
c.
asexual reproduction.
d.
fertilization.
 

 4. 
Cancer is a disease in which cells
a.
grow and divide uncontrollably.
b.
die before they can mature.
c.
stop producing DNA.
d.
die during mitosis.
 

 5. 
Scientists think cancer begins when
a.
a mutation occurs in DNA.
b.
a cell divides too slowly.
c.
DNA replication stops.
d.
cells stop growing.
 

 6. 
What does messenger RNA do during protein synthesis?
a.
copies the coded message from the DNA and carries it into the cytoplasm
b.
copies the coded message from the DNA and carries it into the nucleus
c.
carries amino acids and adds them to the growing protein
d.
copies the coded message from the protein and carries it into the nucleus
 

 7. 
Where does protein synthesis take place?
a.
in the ribosomes in the nucleus of the cell
b.
on the ribosomes in the cytoplasm of the cell
c.
in the chromosomes in the nucleus of the cell
d.
on the chromosomes in the cytoplasm of the cell
 

 8. 
All of the following nitrogen bases in RNA are part of DNA, except
a.
adenine.
b.
guanine.
c.
cytosine.
d.
uracil.
 

 9. 
During DNA replication, adenine (A) always pairs with
a.
guanine (G).
b.
cytosine (C).
c.
thymine (T).
d.
adenine (A).
 

 10. 
What is a mutation?
a.
any change that is harmful to an organism
b.
any change in a gene or chromosome
c.
any change that is helpful to an organism
d.
any change in the phenotype of a cell
 

 11. 
What did Gregor Mendel do to study different characteristics in his genetics experiments?
a.
He studied only asexual plants.
b.
He studied only tall and short pea plants.
c.
He cross-pollinated plants.
d.
He cross-pollinated both plants and animals.
 

 12. 
What does the notation TT mean to geneticists?
a.
two dominant alleles
b.
heterozygous alleles
c.
at least one dominant allele
d.
one dominant and one recessive allele
 

 13. 
What is the probability of producing a tall pea plant from a genetic cross between two hybrid tall pea plants?
a.
one in four
b.
two in four
c.
three in four
d.
four in four
 

 14. 
What does a Punnett square show?
a.
all the possible outcomes of a genetic cross
b.
only the dominant alleles in a genetic cross
c.
only the recessive alleles in a genetic cross
d.
all of Mendel’s discoveries about genetic crosses
 

 15. 
A purebred chicken with white feathers is crossed with a purebred chicken that has black feathers. Each of their offspring has both black and white feathers. Why does this happen?
a.
Both alleles for feather color are dominant.
b.
Both alleles for feather color are recessive.
c.
The alleles for feather color are neither dominant nor recessive.
d.
Several alleles work together to determine the trait.
 

 16. 
What happens during meiosis?
a.
Two sex cells combine.
b.
Chromosome pairs separate and are distributed into new sex cells.
c.
Each sex cell copies itself to form four new chromosomes.
d.
Chromosome pairs remain together when new sex cells are formed.
 

 17. 
An organism’s genotype is its
a.
genetic makeup.
b.
feather color.
c.
physical appearance.
d.
stem height.
 

 18. 
Scientists call an organism that has two different alleles for a trait a
a.
hybrid.
b.
dominant.
c.
purebred.
d.
factor.
 

 19. 
What does the notation Tt mean to geneticists?
a.
two dominant alleles
b.
two recessive alleles
c.
homozygous alleles
d.
one dominant allele and one recessive allele
 

 20. 
What is probability?
a.
the actual results from a series of events
b.
a number that describes how likely it is that an event will occur
c.
the way the results of one event affect the next event
d.
the number of times a coin lands heads up
 

 21. 
If a homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb), what is the probability that an offspring will have black fur?
a.
25 percent
b.
50 percent
c.
75 percent
d.
100 percent
 

 22. 
An organism’s physical appearance is its
a.
genotype.
b.
phenotype.
c.
dominance.
d.
allele.
 

 23. 
An organism that has two identical alleles for a trait is
a.
a phenotype.
b.
tall.
c.
homozygous.
d.
heterozygous.
 

 24. 
Which combination of sex chromosomes results in a male human being?
a.
XX
b.
YY
c.
XY
d.
either XX or YY
 

 25. 
Why are sex-linked traits more common in males than in females?
a.
In males, all alleles on the X chromosome are dominant.
b.
In males, all alleles on the Y chromosome are recessive.
c.
In males, there is usually no matching allele on the Y chromosome to mask the allele on the X chromosome.
d.
In males, any allele on the Y chromosome will be codominant with the matching allele on the X chromosome.
 

 26. 
What must occur for a girl to be colorblind?
a.
Each parent must be colorblind.
b.
Each parent must have the dominant allele for colorblindness.
c.
Each parent must have the recessive allele for colorblindness.
d.
Each parent must have two codominant alleles for colorblindness.
 

 27. 
Hemophilia is caused by a(n)
a.
recessive allele on the X chromosome.
b.
extra chromosome.
c.
dominant allele.
d.
codominant allele.
 

 28. 
What genetic disorder results in abnormally shaped blood cells?
a.
hemophilia
b.
Down syndrome
c.
cystic fibrosis
d.
sickle-cell disease
 

Modified True/False
Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.
 

 29. 
A mutation in a sex cell can be passed to offspring. ____________________

 

Completion
Complete each statement.
 

 30. 
Yeast cells undergo a form of asexual reproduction called ____________________.
 

 

 31. 
A change in DNA is called a(n) ____________________.
 

 

 32. 
Alleles that are neither dominant nor recessive produce an inheritance pattern known as ____________________.
 

 

 33. 
The process in which a parent cell divides twice to produce sex cells is called ____________________.
 

 

 34. 
If D represents the dominant allele of a gene, then ____________________ represents the recessive allele.
 

 

Short Answer
 
 
nar001-1.jpg
 

 35. 
Which trait—white flowers or purple flowers—is controlled by a dominant allele? Which is controlled by a recessive allele? How do you know?
 

 36. 
In which generation are the parents purebred? In which generation are they hybrids?
 

 37. 
In the F1 generation, what is the genotype of the offspring? What is their phenotype?
 

 38. 
In the F2 generation, what percent of the offspring have purple flowers? What is the genotype of the purple-flowered offspring?
 

 39. 
In the F2 generation, what percent of the offspring have white flowers? What are the genotypes of the white-flowered offspring?
 

 40. 
Suppose one of the parents of the F2 generation had been ww instead of Ww. What percent of the offspring would have purple flowers? What percent would have white flowers?
 
 
nar002-1.jpg
 

 41. 
In the Punnett square above, what is the probability that the offspring will have purple flowers? What is the probability that the offspring will have white flowers?
 

 42. 
In an experimental field of F2 generation offspring, a researcher counted 62 plants with purple flowers out of a total of 200 plants, or 31% purple plants. Explain how this is possible.
 

Essay
 

 43. 
Describe what messenger RNA and transfer RNA do during protein synthesis.
 

 44. 
Contrast the effects of harmful and helpful mutations.
 



 
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