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Modern Genetics Study Guide



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.
 

1. 

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

 

2. 

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

 

3. 

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

 

4. 

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

 

5. 

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

 

6. 

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

 

7. 

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

 

8. 

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

 

9. 

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

 

10. 

The goal of DNA fingerprinting is to prepare an encyclopedia that shows the DNA sequence of every gene. _________________________

 

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

11. 

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
 

12. 

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
 

13. 

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.
 

14. 

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

15. 

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

16. 

What factors can affect a person’s height?
a.
genes only
b.
environmental factors only
c.
both genes and environmental factors
d.
the sex chromosomes a person inherits
 

17. 

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

18. 

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.
 

19. 

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 over generations of families
 

20. 

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
 

21. 

Genetic disorders are caused by
a.
pedigrees.
b.
mutations.
c.
dominant alleles.
d.
sickle-shaped cells.
 

22. 

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
 

23. 

What is a karyotype?
a.
blood from a newborn baby
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
 

24. 

How can genetic counselors predict genetic disorders?
a.
by studying karyotypes and pedigree charts
b.
by taking pictures of a baby before it is born
c.
by exploring new methods of genetic engineering
d.
by eliminating codominant alleles in the parents
 

25. 

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

26. 

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
 

27. 

No two people have the same DNA, except for
a.
crime suspects.
b.
brothers.
c.
sisters.
d.
identical twins.
 

28. 

How do police use DNA fingerprinting to help solve crimes?
a.
by proving that a suspect’s blood type matches evidence in a crime
b.
by showing that a suspect’s fingerprints are at a crime scene
c.
by comparing a suspect’s DNA patterns with evidence from a crime scene
d.
by matching phenotypes of suspects with DNA samples
 

29. 

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 splice every gene on a single chromosome in human DNA
d.
to inbreed the best genes on every chromosome in human DNA
 

30. 

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

31. 

One parent of a child has type A blood and the other has type B blood. What is the child’s blood type?
a.
Type A
b.
Type B
c.
Type AB
d.
Type O
 

32. 

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.
 

33. 

Which form of selective breeding crosses genetically different individuals in an attempt to keep the best traits of both parents?
a.
genetic engineering
b.
inbreeding
c.
hybridization
d.
cloning
 

34. 

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

35. 

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.
 

36. 

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.
 

37. 

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

38. 

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.
 

39. 

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

40. 

What procedure helps doctors diagnose a genetic disorder before a baby is born?
a.
genetic engineering
b.
selective breeding
c.
amniocentesis
d.
cloning
 

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. 

Various combinations of ____________________ at each of several genes control human skin color.
 

 

44. 

Improvements in medical care and in ____________________ have altered the effects of genes on height.
 

 

45. 

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

 

46. 

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

 

47. 

A recessive allele can be passed to offspring by a(n) ____________________ who does not show the trait.
 

 

48. 

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

 

49. 

People who have the genetic disorder called ____________________ disease suffer from lack of oxygen in the blood.
 

 

50. 

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

 

51. 

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

 

52. 

A doctor performs a procedure called ____________________ to get cells from the fluid that surrounds a developing baby.
 

 

53. 

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

 

54. 

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

 

55. 

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

 

56. 

_________________________ helps to solve crimes because no two people, except identical twins, have the same DNA.
 

 

57. 

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

 

58. 

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

 

59. 

A selective breeding technique called ____________________ is used to breed purebred dogs.
 

 

60. 

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

 



 
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