5) The number of gamete types from independent assortment of the homologues during meiosis
in humans would be:

A) 21 × 2 (42)
B) 232 (529)
C) 223 (78 million)
D) 46 × 2 (92)

C) 223 (78 million)

6) A female infant is born with several hundred oocytes, each one genetically unique. This is due
to ________.

A) mutation
B) recessive inheritance
C) chromosome deletion
D) independent assortment and random crossover

D) independent assortment and random crossover

7) If we are to consider the variation resulting only from independent assortment and random
fertilization, any resulting offspring represents about one out of ________.

A) 64 zygotes possible
B) 23,000 zygotes possible
C) 64,000 zygotes possible
D) 72 trillion zygotes possible

D) 72 trillion zygotes possible

8) Mitosis differs from meiosis because in meiosis we observe ________.

A) tetrads
B) chromatids
C) centromeres
D) homologues

A) tetrads

9) The reason recessive genetic disorders are more frequent than disorders inherited as dominant
is that ________.

A) dominant genetic disorders are never expressed in males
B) people carrying dominant genetic disorders always die before birth
C) carriers may pass them on to their offspring, unaware that they are carriers
D) recessive genetic disorders are limited to persons of the same ethnicity

C) carriers may pass them on to their offspring, unaware that they are carriers

10) The gene responsible for the condition known as sickle-cell anemia demonstrates ________.

A) incomplete dominance
B) a dominant genetic disorder
C) a sex-linked genetic disorder
D) a recessive genetic disorder

A) incomplete dominance

11) An example of multiple allele inheritance is ________.

A) the ABO blood group
B) the appearance of freckles on the skin
C) the appearance of birthmarks on the skin
D) hair that seems to have several shades of a color

A) the ABO blood grou

12) Which of the following is true concerning environmental influence on genetic expression?

A) It is impossible to alter in any way the expression of a gene in humans.
B) The only time a gene can be influenced by environmental factors is in the second
trimester of the pregnancy.
C) Environmental factors determine the way in which 90 percent of our genes are
expressed.
D) Drugs and nutrition can alter normal gene expression.

D) Drugs and nutrition can alter normal gene expression.

13) Sex chromosomes of a normal male are ________.

A) XX
B) YY
C) XY
D) Any of these, depending on the father

C) XY

14) A woman has blond hair and brown eyes. This statement is best described as indicating
________.

A) allelic pairs
B) recessive traits
C) phenotype
D) genotype

C) phenotype

15) A chromosomal aberration in which part of a chromosome is lost is known as ________.

A) deletion
B) inversion
C) translocation
D) crossing over

A) deletion

16) Inheritance of stature (height) in humans is probably due to ________.

A) polyploidy
B) polymorphism
C) incomplete dominance
D) polygene inheritance

D) polygene inheritance

17) An individual who is heterozygous for a particular trait, yet expresses both alleles of that trait,
is an example of ________.

A) dominance
B) recessive inheritance
C) incomplete dominance
D) sex-linked inheritance

C) incomplete dominance

18) ________ is the most common type of fetal testing.

A) Blood chemistry
B) Amniocentesis
C) A DNA probe
D) CVS

B) Amniocentesis

19) Huntingtonʹs disease involves ________.

A) hypersecretion of growth hormone
B) the presence of an extra chromosome
C) degeneration of the basal nuclei of the brain
D) hyposecretion of thyroxine

C) degeneration of the basal nuclei of the brain

20) One possible scientific explanation for siblings having very different skin color is ________.

A) polygene inheritance, which results in continuous phenotypic variation between
extremes
B) that some people may be in the sun longer than others
C) that the gene for dark skin is dominant over the gene for light skin, and some offspring
inherit chromosomes with one of each allele
D) There is no explanation for the variation

A) polygene inheritance, which results in continuous phenotypic variation between

21) Which of the following statements is true concerning screening?

A) Screening is illegal in over half of the world.
B) Screening can be done only in the first trimester of pregnancy.
C) Genetic screening is rarely done because it yields very little accurate information.
D) Screening can be done before conception by carrier recognition or during fetal testing.

D) Screening can be done before conception by carrier recognition or during fetal testing.

22) The diploid genome contains chromosomes from ________.
A) the father only
B) the mother only
C) each parent, and it synthesizes others
D) both the mother and father, but only about half of the genome from each

D) both the mother and father, but only about half of the genome from each

23) Amyʹs hand was exposed to X rays. A gene in a skin cell of her hand mutated. This mutant
gene ________.

A) will definitely cause skin cancer
B) will replicate itself and be passed on to Amyʹs children
C) will not form an exact duplicate of itself when the cell divides
D) will replicate itself when the cell divides but will not be passed on to Amyʹs offspring

D) will replicate itself when the cell divides but will not be passed on to Amyʹs offspring

Match the following:
24) Lack of skin pigmentation.

A) Tay-Sachs disease
B) Huntington's disease
C) Achondroplasia
D) Albinism
E) Cystic fibrosis

D) Albinism

Match the following:
25) Rare type of dwarfism resulting from

A) Tay-Sachs disease
B) Huntington's disease
C) Achondroplasia
D) Albinism
E) Cystic fibrosis

C) Achondroplasia

Match the following:
26) An unremitting, fatal nervous system

A) Tay-Sachs disease
B) Huntington's disease
C) Achondroplasia
D) Albinism
E) Cystic fibrosis

B) Huntington's disease

Match the following:
27) A condition of excessive mucus
production.

A) Tay-Sachs disease
B) Huntington's disease
C) Achondroplasia
D) Albinism
E) Cystic fibrosis

E) Cystic fibrosis

Match the following:
28) A disorder of brain lipid metabolism

A) Tay-Sachs disease
B) Huntington's disease
C) Achondroplasia
D) Albinism
E) Cystic fibrosis

A) Tay-Sachs disease

29) Select the incorrect statement about Chromosomes and genes.

A) Genes on neighboring but different chromosomes are called linked.
B) Recombinant chromosomes have segments of DNA from each parent on the same
chromosome.
C) The longer a chromosome, the more crossovers are expected.
D) A personʹs genetic makeup is referred to as his or her genotype.

A) Genes on neighboring but different chromosomes are called linked.

30) The main way a recessive allele would be expressed even when only one copy is present
would be ________.

A) dominance
B) recessive inheritance
C) sex-linked inheritance
D) incomplete dominance

C) sex-linked inheritance

31) A couple whose blood types are A (IAi) and B (IBi) may have a child with which of the
following blood types?

A) AB only
B) A and B only
C) A, B, AB, and O
D) AB and O only

C) A, B, AB, and O

32) Gene mutations in the sex chromosomes of the human would tend to become visibly
expressed ________.

A) more frequently in males
B) more frequently in females
C) equally frequently in both sexes
D) in neither males or females

A) more frequently in males

33) For which of the following are newborn infants not routinely screened at birth?

A) PKU
B) color blindness
C) imperforate anus
D) congenital hip dysplasia

B) color blindness

Match the following:
34) Actual genetic makeup.

A) Recessive
B) Sex chromosomes
C) Genotype
D) Homozygous

C) Genotype

Match the following:

35) A chromosome pair that may
be very different in size.

A) Recessive
B) Sex chromosomes
C) Genotype
D) Homozygous

B) Sex chromosomes

Match the following:

36) Genes not expressed unless
they are present in
homozygous condition.

A) Recessive
B) Sex chromosomes
C) Genotype
D) Homozygous

A) Recessive

Match the following:

37) Situation in which an
individual has identical
alleles for a particular trait.

A) Recessive
B) Sex chromosomes
C) Genotype
D) Homozygous

D) Homozygous

Match the following

38) Actual genetic makeup.

1. A) Genotype
2. B) Sex chromosomes
3. C) Homozygous
4. D) Recessive

A) Genotype

Match the following

39) A chromosome pair that may be very different in size.

1. A) Genotype
2. B) Sex chromosomes
3. C) Homozygous
4. D) Recessive

B) Sex chromosomes

Match the following

40) Genes not expressed unless they are present in homozygous condition.

.

1. A) Genotype
2. B) Sex chromosomes
3. C) Homozygous
4. D) Recessive

D) Recessive

Match the following

41) Situation in which an individual has identical alleles for a particular trait.

1. A) Genotype
2. B) Sex chromosomes
3. C) Homozygous
4. D) Recessive

C) Homozygous

42) When two genes are on the same chromosome, they are considered linked.

TRUE

43) The X chromosome is considerably larger than the Y chromosome.

TRUE

44) The expression of all physical traits is strictly due to the inheritance of specific genes.

FALSE

45) Some segments of the Y chromosome have no counterpart on the X chromosome.

TRUE

46) The same allele can have a different effect depending on which parent it comes from.

TRUE

47) Hereditary characteristics are transmitted to offspring by genes.

TRUE

Match the following:

48) Genes for the same trait that have
different expressions.

A) Heterozygous

B) Dominant
C) Autosomes
D) Allele

D) Allele

Match the following:

49) The gene allele that suppresses or
masks the expression of the other
allele.

A) Heterozygous
B) Dominant
C) Autosomes
D) Allele

B) Dominant

Match the following:

50) Situation in which an individual has
different alleles making up the
genotype for a particular trait.

A) Heterozygous
B) Dominant
C) Autosomes
D) Allele

A) Heterozygous

Match the following:

51) Chromosomes regulating most body
characteristics.

A) Heterozygous
B) Dominant
C) Autosomes
D) Allele

C) Autosomes

52) Alleles may code for alternative expressions of a genetic trait.

TRUE

53) Hemophilia is an X-linked condition caused by a recessive gene.

TRUE

54) Environmentally produced phenotypes that mimic conditions that may be caused by genetic
mutation are called phenocopies.

TRUE

55) Most genetic disorders are inherited through dominant genes.

FALSE

56) A Punnett square is a diagram that may be used to figure out the possible combinations of genes
for a trait.

TRUE

57) Two alleles expressing exactly the same information for a trait are designated as ________.

A) hemizygous

B) homozygous

C) monogamous

D) heterozygous

B) homozygous

58) Dominant alleles are so called because under most circumstances they ________.
A) code for most phenotypic and genotypic expressions of a trait
B) suppress the expression of other alleles
C) code for genes that are never considered lethal
D) code only for tallness and dark skin

B) suppress the expression of other alleles

59) Recessive genes are usually expressed in humans only when ________.
A) both alleles are exactly the same, or homozygous
B) they are coding for genetic diseases
C) they are coding for skin color
D) the organism is in the embryonic stage

A) both alleles are exactly the same, or homozygous

60) Those characteristics that can be determined on superficial inspection of an individual are known
as ________.
A) polyspermic

B) phenotypic

C) polygenic

D) genotypic

B) phenotypic

61) Is genetic diversity due entirely to inherited genes on the sex chromosomes?
A) Yes, because the female has two X chromosomes and the male has only one X chromosome.
B) No, because genetic diversity has nothing to do with the sex chromosomes but is due to
crossing-over of chromosomes, independent assortment of chromosomes, and segregation of
chromosomes.
C) Yes, because the male has a Y chromosome.
D) Yes, because genetic diversity is due to the Y influence on the autosomes.

B) No, because genetic diversity has nothing to do with the sex chromosomes but is due to
crossing-over of chromosomes, independent assortment of chromosomes, and segregation of
chromosomes.

62) A female infant is born with several hundred oocytes, each one genetically unique. This is due to
________.
A) mutation
B) independent assortment and random crossover
C) chromosome deletion
D) recessive inheritance

B) independent assortment and random crossover

63) In meiosis the spermatozoa that are produced are genetically unlike each other and unlike the cell
that produces them. This is one reason for the great variation among humans. What causes this
effect?
A) crossing-over, chromsome segregation, and independent assortment
B) chromosome segregation and independent assortment only
C) crossing-over and chromosome segregation only
D) crossing-over and independent assortment only

D) crossing-over and independent assortment only

64) The reason recessive genetic disorders are more frequent than disorders inherited as dominant is
that ________.
A) carriers may pass them on to their offspring, unaware that they are carriers
B) dominant genetic disorders are never expressed in males
C) recessive genetic disorders are limited to persons of the same ethnicity
D) people carrying dominant genetic disorders always die before birth

A) carriers may pass them on to their offspring, unaware that they are carriers

65) The gene responsible for the condition known as sickle-cell anemia demonstrates ________.

A) a dominant genetic disorder

B) a sex-linked genetic disorder

C) incomplete dominance

D) a recessive genetic disorder

C) incomplete dominance

66) An example of multiple-allele inheritance is ________.
A) the appearance of birthmarks on the skin
B) the appearance of freckles on the skin
C) hair that seems to have several shades of a color
D) the ABO blood group

D) the ABO blood group

67) Sex chromosomes of a normal male are ________.

A)YY
B)XY
C)XX
D) any of these, depending on the father

B) XY

68) Huntington's disease involves ________.
A) hyposecretion of thyroxine
B) the presence of an extra chromosome
C) hypersecretion of growth hormone
D) degeneration of the basal nuclei of the brain

D) degeneration of the basal nuclei of the brain

69 )The term lethal dominant gene indicates that the gene causes death only when the individual is
homozygous.

FALSE

70) In incomplete dominance, the heterozygote has a phenotype intermediate between that of
homozygous-dominant and homozygous-recessive individuals.

TRUE

71) The two equally useful avenues for detecting carriers are pedigrees and the use of Punnett squares.

FALSE

72) Normal vision is dictated by the autosomal dominant genes.

FALSE

73) Genetic segregation implies that the members of the allele pair determining each trait are
distributed to different gametes during mitosis.

FALSE

74) Genetic variation results from the crossing over and exchange of chromosomal parts that occur
during meiosis II.

FALSE

75) Small RNAs control the timing of programmed cell death during development.

TRUE

76) Mitochondrial genes are free of errors. As a result, all genetic problems are due exclusively to
nuclear genes.

FALSE

77) It is possible for a baby to have type O blood if neither parent is type O.

TRUE

Match the following

78) The X and Y chromosomes are considered the ________ chromosomes.

A SEX-LINKED

B) RECESSIVE

C) DOMINANT

D) PHENOTYPE

E) SEX

E) SEX

79) An allele that completely masks the expression of the other alleles is called ________.

A SEX-LINKED

B) RECESSIVE

C) DOMINANT

D) PHENOTYPE

E) SEX

C) DOMINANT

80) Observable characteristics expressed by the genes for a trait are called the ________.

A SEX-LINKED

B) RECESSIVE

C) DOMINANT

D) PHENOTYPE

E) SEX

D) PHENOTYPE

81) Albinism is a good example of a(n) ________ trait.

A SEX-LINKED

B) RECESSIVE

C) DOMINANT

D) PHENOTYPE

E) SEX

B) RECESSIVE

82) Color blindness is a(n) ________ trait.

A SEX-LINKED

B) RECESSIVE

C) DOMINANT

D) PHENOTYPE

E) SEX

A) SEX-LINKED