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Name: 
 

Modern Genetics



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

 1. 

Which of these traits is controlled by a gene with multiple alleles?
a.
straight hairline
b.
smile dimples
c.
widow’s peak
d.
blood type
 

 2. 

What are multiple alleles?
a.
more than two genes that control a trait
b.
three or more forms of a gene that code for a single trait
c.
three or more chromosomes that determine a trait
d.
more than two codominant genes in a chromosome
 

 3. 

Why does height in humans have such a wide variety of phenotypes?
a.
Height is controlled by at least four genes.
b.
The gene for height has only two alleles.
c.
Height is controlled by sex-linked genes.
d.
Height is controlled by a recessive allele.
 

 4. 

What controls variations in skin color among humans?
a.
a person’s diet
b.
many genes
c.
multiple alleles of a single gene
d.
two alleles of a single gene
 

 5. 

Which of these human traits is altered by variations in environment?
a.
hairline
b.
height
c.
smile dimples
d.
blood type
 

 6. 

What factors can affect a person’s height?
a.
genes only
b.
both genes and environmental factors
c.
a person’s blood type
d.
a person’s karyotype
 

 7. 

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

 8. 

Why are sex-linked traits more common in males than in females?
a.
All alleles on the X chromosome are dominant.
b.
All alleles on the Y chromosome are recessive.
c.
A recessive allele on the X chromosome will always produce the trait in a male.
d.
Any allele on the Y chromosome will be codominant with the matching allele on the X chromosome.
 

 9. 

How does a geneticist use pedigrees?
a.
to create genetic crosses
b.
to replicate identical strings of DNA
c.
to prove that sex-linked traits are caused by codominant alleles
d.
to trace the inheritance of traits in humans
 

 10. 

What is a pedigree?
a.
a chart that tracks which members of a family have a particular trait
b.
a geneticist who studies the inheritance of traits in humans
c.
a picture of all of the chromosomes in a cell
d.
an allele passed from parent to child on a sex chromosome
 

 11. 

Genetic disorders are caused by
a.
pedigrees.
b.
DNA mutations or changes in chromosomes.
c.
dominant alleles only.
d.
recessive alleles only.
 

 12. 

Which genetic disorder causes the body to produce unusually thick mucus in the lungs and intestines?
a.
hemophilia
b.
Down syndrome
c.
cystic fibrosis
d.
sickle-cell disease
 

 13. 

What is a karyotype?
a.
a sex-linked genetic disorder
b.
a picture of a baby before it is born
c.
a picture of the chromosomes in a cell
d.
fluid that surrounds a baby before it is born
 

 14. 

What would be the best way to predict the probability of a baby having cystic fibrosis?
a.
by studying the parents’ karyotypes
b.
by studying the family’s pedigree chart
c.
by exploring new methods of genetic engineering
d.
by determining whether the parents have codominant alleles
 

 15. 

Cloning results in two organisms that are
a.
both adult mammals.
b.
produced from cuttings.
c.
genetically similar.
d.
genetically identical.
 

 16. 

Which of these is an example of the benefits of genetic engineering?
a.
cross-breeding to create disease-resistant crops
b.
creating human insulin to treat people with diabetes
c.
analyzing karyotypes and pedigree charts
d.
growing a new plant from a cutting
 

 17. 

The Human Genome Project can help genetic engineers produce human proteins because
a.
identical twins have identical DNA.
b.
the Human Genome Project has determined the structure of transfer RNA.
c.
the Human Genome Project has determined the structure of human proteins.
d.
to produce a protein, geneticists must know the sequence of DNA bases that codes for the protein.
 

 18. 

What is the purpose of the Human Genome Project?
a.
to identify the DNA sequence of every gene in the human genome
b.
to clone every gene on a single chromosome in human DNA
c.
to cure genetic diseases
d.
to inbreed the best genes on every chromosome in human DNA
 

 19. 

What is a genome?
a.
all the cells produced during meiosis
b.
all the plasmids produced from inserting DNA into a cell
c.
all the DNA in one cell of an organism
d.
all the karyotypes in a cell
 

 20. 

Both parents of a child have type A blood. What might their child’s blood type be?
a.
Type A only
b.
Type A or type B
c.
Type A or type O
d.
Type A or type AB
 

 21. 

Sex-linked genes are genes on
a.
the X chromosome only.
b.
the Y chromosome only.
c.
the X and Y chromosomes.
d.
all 23 pairs of chromosomes.
 

 22. 

In an attempt to produce a potato that tastes good and also resists disease, plant breeders crossed a potato variety that tastes good with a variety that resists disease. This technique is an example of
a.
genetic engineering.
b.
inbreeding.
c.
hybridization.
d.
cloning.
 

 23. 

Which form of selective breeding crosses parents with the same or similar sets of alleles?
a.
fertilization
b.
inbreeding
c.
hybridization
d.
cloning
 

 24. 

A carrier is a person who has
a.
one recessive and one dominant allele for a trait.
b.
two recessive alleles for a trait.
c.
two dominant alleles for a trait.
d.
more than two alleles for a trait.
 

 25. 

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.
 

 26. 

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

 27. 

Down syndrome most often occurs when
a.
a person inherits a recessive allele.
b.
chromosomes fail to separate properly during meiosis.
c.
sickle-shaped cells become stuck in blood vessels.
d.
blood fails to clot properly.
 

 28. 

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

 29. 

Many characteristics are affected by interactions between genes and
a.
chromosomes.
b.
the environment.
c.
alleles.
d.
carriers.
 

 30. 

Adults with Down syndrome can often find work because they have received
a.
folic acid.
b.
physical therapy.
c.
education and job training.
d.
genetic counseling.
 

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

 31. 

Even if a gene has multiple alleles, a person cannot have more than three of those alleles. _________________________

 

 32. 

Traits that have many different phenotypes, such as height and skin color, are often controlled by a single gene. _________________________

 

 33. 

A person’s environment can affect his or her genotype for certain traits, such as height. _________________________

 

 34. 

Sex-linked traits that are controlled by recessive alleles are more likely to show up in males. _________________________

 

 35. 

A male is represented by a square in a pedigree. _________________________

 

 36. 

A genetic disorder in which an abnormal form of hemoglobin is produced is hemophilia. _________________________

 

 37. 

A doctor can look at the chromosomes of a cell in a karyotype. _________________________

 

 38. 

The technique called cloning produces an organism that is genetically identical to its parent. _________________________

 

 39. 

Except for identical twins, all people have the same DNA. _________________________

 

 40. 

The goal of DNA fingerprinting is to identify the DNA sequence of every gene. _________________________

 

Completion
Complete each sentence or statement.
 

 41. 

The three alleles on the single gene that controls blood type are said to be ____________________ alleles.
 

 

 42. 

When many genes control a trait, the trait will show a large number of ____________________.
 

 

 43. 

Improvements in ____________________ can alter the effects of genes on height.
 

 

 44. 

A person’s surroundings, or ____________________, can change the effects of a person’s genes.
 

 

 45. 

An egg that is fertilized by a sperm cell with a(n) ____________________ chromosome will develop into a female.
 

 

 46. 

A carrier is a person who has one ____________________ allele for a trait.
 

 

 47. 

A(n) ____________________ is used to track the occurrence of a trait in a family.
 

 

 48. 

People who have the genetic disorder called ____________________ suffer from abnormally low levels of oxygen in the blood.
 

 

 49. 

A person who has the genetic disorder called ____________________ bleeds easily.
 

 

 50. 

Down’s syndrome is caused by the presence of an extra ____________________.
 

 

 51. 

A karyotype can be used to diagnose the genetic disorder called ____________________.
 

 

 52. 

Breeders use a technique called ____________________ to cross genetically different individuals.
 

 

 53. 

A gene from one organism is inserted into the DNA of another organism in the process known as _________________________.
 

 

 54. 

Scientists in the Human Genome Project are working to identify the ____________________ sequence of every human gene.
 

 

 55. 

All of the DNA in one cell of an organism is called a(n) ____________________.
 

 

 56. 

A selective breeding technique called ____________________ has been used to breed purebred racehorses.
 

 

 57. 

A gene is said to have multiple alleles if it has more than ____________________ alleles.
 

 

 58. 

A(n)____________________ helps couples understand their chances of having a child with a genetic disorder.
 

 

 59. 

A pattern produced from fragments of the DNA of a specific person is called a(n) ____________________.
 

 

 60. 

A karyotype can be used to determine the number of ____________________ in a person’s cells.
 

 

Short Answer
 
 
Use the diagram to answer each question.

mg_files/i0650000.jpg
 

 61. 

What do the circles in the pedigree represent? What do the squares represent?
 

 62. 

Which pairs of individuals in the pedigree have children?
 

 63. 

Which individuals have the trait that is traced by the pedigree?
 

 64. 

Which individuals are carriers of the trait that is traced by the pedigree?
 

 65. 

Which individuals neither have the trait nor are carriers?
 

 66. 

Could the trait that is traced by this pedigree be sex-linked? Explain why or why not.
 
 
Use the diagram to answer each question.

mg_files/i0720000.jpg
 

 67. 

Identify structures A and B. What do these structures contain?
 

 68. 

Explain what is happening in Step 1.
 

 69. 

Explain what is happening in Step 2.
 

 70. 

Explain what is happening in Step 3.
 

 71. 

Explain what is happening in Step 4.
 

 72. 

Why are bacteria often used in genetic engineering?
 

Essay
 

 73. 

Human eyes come in a variety of colors ranging from light blue to very dark brown. Explain why eye color is not likely to be controlled by a single gene.
 

 74. 

Is it possible for a son to inherit an allele on an X chromosome from his father? Explain why or why not.
 

 75. 

Explain what causes cystic fibrosis and describe its effects on the body.
 

 76. 

Explain how you can tell the sex of a person by looking at that person’s karyotype.
 

 77. 

A plant breeder clones a plant with beautiful flowers. Define cloning and explain how the cloned offspring compare to the parent plant.
 

 78. 

Contrast hybridization and inbreeding.
 

 79. 

A person with blood type AB has the alleles IA and IB. A person with blood type O has the alleles ii. Is it possible for a person with blood type AB to have a child with blood type O? Explain why or why not.
 

 80. 

What factors determine human height?
 



 
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