Which of the following terms refers to the genes of an individual?
genotype
phenotype
gamete
probability
autosomal
answer
genotype
*The genetic make-up of an individual is called the genotype.
(Section 21.01)
question
Which of the following is an example of a recessive genotype?
aa
Aa
short
AA
ab
answer
aa
*Recessive genotypes are designated with two lower case letters. Dominant genotypes are designated with two upper case letters or one upper case and one lower case letter. Short is a phenotypic description.
(Section 21.01)
question
Which of the following is a dominant allele?
A
a
AA
ab
Ab
answer
A
*An allele is represented by a single, capitalized letter.
(Section 21.01)
question
Which of the following genotypes is heterozygous?
Aa
Ab
aB
ab
aa
answer
Aa
*A heterozygous genotype is indicated by two of the same letters, one capital and one lower case.
(Section 21.01)
question
Which of the following represents a dihybrid cross?
ff x ff
Gg x gg
AAbb x Aabb
AAbb x aaBB
Ss x ss
answer
AAbb x aaBB
*A dihybrid cross involves two different sets of alleles that are not identical to each other.
(Section 21.02)
question
The square that is used to make all the possible combinations of gametes is called a Punnett square.
True
False
answer
True
*Reginald Punnett introduced the Punnett square in his genetic classes in 1909.
(Section 21.02)
question
If two parents who are unaffected have a child that is affected, then the parents are both considered bearers.
True
False
answer
False
*Two parents who are unaffected but are heterozygous for a recessive disorder are considered carriers.
(Section 21.03)
question
Which of the following is not an autosomal recessive disorder?
Marfan syndrome
Tay-Sachs disease
cystic fibrosis
sickle cell disease
all are autosomal recessive disorders
answer
Marfan syndrome
*Marfan syndrome is inherited as an autosomal dominant disorder.
(Section 21.03)
question
Which of the following genetic disorders is due to a lack of the lysosome enzyme hex A?
cystic fibrosis
Tay-Sachs disease
Huntington disease
sickle-cell disease
Marfan syndrome
answer
Tay-Sachs disease
*Tay-Sachs disease is due to the lack of the lysosome enzyme hex A.
(Section 21.03)
question
It is estimated that there are fewer than 100 genetic diseases caused by single gene mutations in humans.
True
False
answer
False
*It is estimated that there are over 4000 identified genetic disorders caused by single gene mutations in humans.
(Section 21.03)
question
Which of the following disorders is caused by a defect in the production of an elastic connective tissue protein called fibrillin?
cystic fibrosis
Tay-Sachs disease
Marfan syndrome
Huntington disease
sickle-cell disease
answer
Marfan syndrome
*Marfan syndrome is caused by a defect in the production of an elastic connective tissue protein called fibrillin.
(Section 21.03)
question
Which of the following disorders is a trinucleotide repeat disorder?
Marfan syndrome
sickle-cell disease
cystic fibrosis
Tay-Sachs disease
Huntington disease
answer
Huntington disease
*Huntington disease is caused by the base sequence CAG repeated over and over again in the protein huntingtin.
(Section 21.03)
question
How is familial hypercholesterolemia inherited?
autosomal recessive
autosomal dominant
incompletely dominant
codominant
sex-linked dominant
answer
incompletely dominant
*Familial hypercholesterolemia is an incompletely dominant disorder.
(Section 21.04)
question
What is the genotype of a person with type O blood?
IAIA
IAIB
IAi
IBi
ii
answer
ii
*The person's genotype will be ii.
(Section 21.04)
question
Which of the following designations indicates a sex-linked trait?
A
I^A
X^B
a
i
answer
X^B
*i
A sex-linked trait is shown as the letter attached to the X chromosome. A and a are alleles for autosomal traits. IA and i are the alleles for blood types.
(Section: 21.05)
question
A male inherits his X linked allele from his mother.
True
False
answer
True
*A man will inherit his X allele from his mother and his Y allele from his father.
(Section 21.05)
question
Which of the following X-linked recessive disorders is characterized by a degeneration of the muscles?
Fragile X
Duchenne's
color blindness
hemophilia
malaria
answer
Duchenne's
*Duchenne's muscular dystrophy is characterized by a degeneration of the muscles. Fragile X is characterized by mental impairment. Color blindness is the inability to distinguish between various colors, typically red and green. Hemophilia is the inability for the blood to clot normally. Malaria is caused by a protist and is not an X linked disorder.
(Section 21.05)
question
Which of the following traits is an X-linked recessive disorder?
Color blindness
Tay-Sachs
Cystic fibrosis
Sickle-cell disease
Marfan syndrome
answer
Color blindness
*Color blindness is a X-linked recessive disorder. Tay-Sachs, cystic fibrosis, and sickle-cell disease are autosomal dominant disorders. Marfan syndrome is an autosomal recessive disorder.
(Section 21.05)
question
When you describe a person as having attached ear lobes, you are describing their genotype.
True
False
answer
false
*You are describing their phenotype, or the physical appearance of the trait.
(Section 21.01)
question
When describing someone as "lactose intolerant", you are describing their
genotype.
phenotype.
alleles.
genome.
none of these
answer
phenotype
*Lactose intolerant is a description of the physical characteristic of the individual, therefore, it is a phenotype. The genotype is the genetic makeup of the individual. The alleles and genome are the genetic material contained in the nucleus of the individual.
(Section 21.01)
question
Which of the following would not be a possible way to list someone's genotype?
BB
Bb
AB
bb
AA
answer
AB
*A genotype usually involves 2 of the same letters--either both capitalized, both lower case, or one of each.
(Section 21.01)
question
While a locus refers to a unit of heredity, a gene refers to a specific position on a chromosome.
True
False
answer
false
*A gene refers to a unit of heredity, while a locus refers to a specific position on a chromosome.
(Section 21.01)
question
Unattached earlobes are a dominant trait in humans. Which phenotype is most likely for an individual with the genotype EE?
both earlobes are unattached
both earlobes are attached
the right earlobe is attached and the left earlobe is
unattached
the right earlobe is unattached and the left earlobe is attached
both earlobes are extremely elongated
answer
both earlobes are attached
*Since unattached earlobes are a dominant trait in humans the genotypes EE or Ee would produce unattached earlobes of both ears. Individuals would not have one attached earlobe and one unattached earlobe.
(Section 21.01)
question
An allele is to a gene, as a locus is to a
gamete.
phenotype.
chromosome.
genotype.
unit of heredity.
answer
chromosome
*An allele is an alternate form of a gene, while a locus is a specific position on a chromosome.
(Section 21.01)
question
Which of the following individuals has a recessive phenotype?
AA
Aa
AaBb
aabb
aAbB
answer
aabb
*Recessive phenotypes are represented by lower case letters. Dominant phenotypes are represented by two capital letters or by one capital and one lower case letter.
(Section 21.01)
question
There are two different alleles for the number of fingers on the hands: 5 finger allele and 6 finger allele. When both the 5 finger allele and the 6 finger allele are present in the same individual, the individual has 6 fingers on the hands. Which allele is dominant?
5 fingers
6 fingers
1 finger
11 fingers
7 fingers
answer
6 fingers
*When both alleles are present, the dominant allele is expressed while the recessive allele is hidden. This would produce an individual with 6 fingers.
(section 21.01)
question
There is a single gene that controls the ability to taste PTC paper. The ability to taste is dominant to the inability to taste. If you can taste the paper, it is very bitter. Which of the following genotypes can taste the paper?
only PP
both PP and Pp
both PP and pp
only Pp
only pp
answer
both PP and Pp
*Both Pp and Pp genotypes would be able to taste the bitter taste of PTC paper.
(Section 21.01)
question
Clasp your hands together (without thinking about it). Which thumb is on top every time you do this? The dominant phenotype is left thumb on top. If you have the genotype "tt", which thumb is on top?
left
right
left 50% of the time and right 50% of the time
left 25% of the time and right 75% of the time
left 75% of the time and right 25% of the time
answer
right
*The genotype "tt" would be the recessive phenotype, so the right thumb would be on top all of the time.
(Section 21.01)
question
Which of the following represents a gamete with a dominant allele?
A
b
AA
Aa
bb
answer
A
*A gamete only has one allele for a particular trait and the dominant allele would be a capital letter.
(Section 21.02)
question
If the mother's genotype is aa, all of her eggs will be identical for this trait.
True
False
answer
true
*Since the mother only has 1 type of allele (lower case a), all of her eggs will be identical for this trait.
(Section 21.02)
question
Dad has a genotype of AaBb. How many different kinds of sperm can he produce?
one
two
three
four
five
answer
four
*Dad can produce four different types of gametes (sperm): AB, Ab, aB, and ab.
(Section 21.02)
question
Which of the following represents a cross to determine if an individual is homozygous dominant or heterozygous?
Aa x aa
AA x AA
aa x aa
Aa x AA
Aa x Aa
answer
Aa x aa
*A type of cross involves a dominant phenotype (unknown genotype) crossed with a homozygous recessive.
(Section 21.02)
question
If you want to know the probability that tossing two coins will result in a particular outcome (two heads, for example), you use the
product rule.
sum rule.
punnett rule.
Bergman's rule.
genetics rule.
answer
product rule
*The product rule gives the chance of two different events (the two coins being tossed) occurring simultaneously.
(Section 21.02)
question
Probability calculations in which the word "or" is used involve the product rule.
True
False
answer
false
*Probability calculations in which the word "or" is used, such as "heads or tails," involve the use of the sum rule.
(Section 21.02)
question
The probability of tossing a coin and having it be heads or tails is
1/4.
1/2.
1.
0.
2.
answer
1
*The probability of tossing a coin and having it be either heads or tails is 1. The probability of it being tails is 1/2 and the probability of it being heads is 1/2, and the sum rule is involved (1/2 + 1/2 = 1).
(Section 21.02)
question
In a cross of Ff x Ff, the probability of having a dominant phenotype is
1/4.
1/3.
1/2.
2/3.
3/4.
answer
3/4
*Three out of four of the offspring will have a dominant phenotype.
(Section 21.02)
question
In a cross of Ss x Ss, the probability of having a heterozygous genotype is
1/4.
1/3.
1/2.
2/3.
3/4.
answer
1/2
*Two out of four of the offspring, or 1/2, will have a heterozygous genotype.
(Section 21.02)
question
In a cross of a homozygous dominant parent and a homozygous recessive parent, what is the ratio of offspring that will exhibit the recessive phenotype?
0.
1/4.
1/2.
3/4.
1.
answer
0
*None of the offspring will exhibit the recessive phenotype. AA x aa will yield 100% Aa offspring.
(Section 21.02)
question
In a dihybrid cross, in which both parents are heterozygous for both traits, what is the probability that the offspring will exhibit both of the dominant phenotypes?
1/16.
3/16.
6/16.
9/16.
1.
answer
9/16
*Nine out of sixteen of the offspring will exhibit both of the dominant traits phenotypically. AaBb x AaBb will yield 3/4 dominant for A and 3/4 dominance for B. 3/4 x 3/4 = 9/16.
(Section 21.02)
question
In a dihybrid cross, if the resulting ratios are 1:1:1:1, what are the genotypes of the parents?
GgRr x ggrr
GGRR x ggrr
GgRr x GgRr
Gg x Rr
GG x RR
answer
GgRr x ggrr
*A dihybrid would involve an individual with the genotype GgRr. In order to have a 1:1:1:1 ratio, the other parent must be homozygous recessive for both traits.
(Section 21.02)
question
Which of the following is not a characteristic of an autosomal recessive disorder pedigree?
Heterozygotes have an affected phenotype.
Affected children can have unaffected parents.
Two affected parents will always have affected children.
Both males and females are affected with equal frequency.
Affected individuals with homozygous unaffected mates will have unaffected children.
answer
Heterozygotes have an affected phenotype.
*In an autosomal recessive disorder, heterozygotes have an unaffected phenotype.
(Section 21.03)
question
In a pedigree, an affected male would be designated by
an open circle.
a shaded circle.
an open square.
a shaded square.
a square with a line through it.
answer
a shaded square
*Affected individuals are shaded, and a male is represented by a square.
(Section 21.03)
question
Julie has a genetic disorder. Julie and her husband, Shane, have three children, none of which have the genetic disorder. How is this disorder most likely inherited?
autosomal dominant.
autosomal recessive.
heterozygous dominant.
The environment influences the trait instead of the genetics.
100% inheritance from the father since the children are not affected.
answer
autosomal recessive.
*If this is an autosomal recessive disorder, then Julie's genotype is aa. If Shane's genotype is AA, none of their children will have the genetic disorder. If Shane's genotype is Aa, then half of their children may be affected. If this were an autosomal dominant disorder, then Julie's genotype is AA or Aa. Shane would be aa. Then either all or half of their children would be affected.
(Section 21.03)
question
Which of the following is not a characteristic of an autosomal dominant disorder pedigree?
Affected children will usually have unaffected parents.
Heterozygotes are affected.
Two affected parents can produce an unaffected child.
Both males and females are affected with equal frequency.
Two unaffected parents will not have affected children.
answer
Affected children will usually have unaffected parents.
*Affected children will usually have an affected parent.
(Section 21.03)
question
Which variable has the stronger influence on the color of an individuals skin?
the individuals phenotype
the amount of time spent in the sun
the amount of time spent in the sun and the individuals genotype
the individuals genotype
neither the sun nor the individuals genotype have any influence on the individuals skin color
answer
the amount of time spent in the sun and the individuals genotype
*Skin color is due to a combination of an individuals genotype as well as the environmental influence.
(Section 21.04)
question
Even though sickle-cell disease is inherited as an autosomal recessive disorder, the heterozygote can express some variation of the recessive phenotype.
True
False
answer
true
*Sickle-cell heterozygotes have sickle-cell traits in which the blood cells are normal unless they experience dehydration or mild oxygen deprivation.
(Section 21.03)
question
Which of the following traits/disorders is controlled by multiple genes?
skin color
Tay-Sachs disease
ABO blood type
familial hypercholesterolemia
curly hair
answer
skin color
*Skin color is controlled by several sets of alleles. It is a polygenic trait.
(Section 21.04)
question
The definition of a multifactorial trait is one in which more than one set of alleles is involved in which the environment plays no role.
True
False
answer
false
*A multifactorial trait is a polygenic trait that is also influenced by the environment.
(Section 21.04)
question
There is a trait with two alleles. One allele codes for red while the other allele codes for white. If this trait is inherited in a codominant manner, what color will the offspring be?
white
red
pink
yellow
red and white and pink striped
answer
pink
*Both colors would be expressed, so the offspring would be a blend of both colors, resulting in a pink offspring.
(Section 21.04)
question
Which of the following traits would not be considered multifactorial?
alcoholism
suicide risk
cleft lip/palate
diabetes
ABO blood type
answer
ABO blood type
*ABO blood type is not a polygenic trait influenced by the environment.
(Section 21.04)
question
Of the three possible alleles for the ABO blood type, each individual can have how many?
one
two
three
none
half an allele
answer
two
*Because each individual is diploid, each can only carry 2 alleles.
(Section 21.04)
question
If an individual has the A blood type, how many different genotypes can they possess?
one
two
three
four
five
answer
two
*The individual can be I^AI^A or I^Ai.
(Section 21.04)
question
If a person with type B blood marries a person with type A blood, what phenotypes can their children be?
all type A
all type B
types A and O
types B and O
types A, B, O, and AB
answer
types A, B, O, and AB
*If both parents are heterozygous, all four blood types are possible: A, B, O, and AB.
(Section 21.04)
question
Which of the following represents the genotype of a male who is color-blind?
X^BX^B
X^BX^b
X^bX^b
X^bY
X^BY
answer
X^bY
*A male who is color-blind would have an X chromosome with a "b" allele and a Y chromosome.
(Section 21.05)
question
Most of the sex-linked traits are found only on the X chromosome.
True
False
answer
true
*Very few Y-linked alleles have been found on the much smaller Y chromosome.
(Section 21.05)
question
Which of the following is not a characteristic of an X-linked recessive disorder pedigree?
An affected son can have normal parents.
If a female has the trait, her father must also have it.
The characteristic often skips a generation.
More females than males are affected.
If a woman has the characteristic, all of her sons will have it.
answer
More females than males are affected.
*In an X-linked recessive disorder pedigree, more males than females are affected.
(Section 21.05)
question
How are Fragile X syndrome and Huntington disease similar?
Both exhibit a late onset in life.
Both are trinucleotide repeat expansion disorders.
Both affect the muscles and lead to eventual paralysis.
Both cause autism.
Both are found only in males.
answer
Both are trinucleotide repeat expansion disorders.
*Both diseases involve repeats of three nucleotides.
(Section 21.05)
question
If a mother is a carrier for color-blindness and her husband is not, which of the following children are most likely?
1 normal daughter, 1 carrier daughter, 1 normal son, and 1
color-blind son
2 normal daughters, 1 normal son, and 1 color-blind son
2 carrier daughters, 1 normal son, and 1 color-blind son
1 normal daughter, 1 carrier daughter, and 2 normal sons
1 normal daughter, 1 carrier daughter, and 2 color-blind sons
answer
1 normal daughter, 1 carrier daughter, 1 normal son, and 1
color-blind son
*If a mother is a carrier for color-blindness (X^BX^b) and the father is normal (X^BY) they would statistically produce a daughter who is normal, one daughter who is a carrier, one son who is normal, and one son who is color-blind.
(Section 21.05)
question
In an X-linked dominant trait, affected males pass the trait only to daughters.
True
False
answer
true
*Since daughters must inherit an X chromosome from their fathers, they would receive an X chromosome with the dominant trait.
(Section 21.05)
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