Chapter 6 Study Guide Flashcards
What kind of trait would be expected to affect more females than males?
autosomal recessive
autosomal dominant
X-linked recessive
X-linked dominant
Y-linked
x-linked dominant
What kind of trait would be expected to affect more females than males?
autosomal recessive
autosomal dominant
X-linked recessive
X-linked dominant
Y-linked
monozygotic twins
Monozygotic twins share 100% of their genes and should show the highest concordance for traits that are genetically influenced.
A(n) ___________ is a picture of a complete set of chromosomes from an individual.
X-ray
pedigree
karyotype
proband
concordance
karyotype
Distinguishing autosomal dominant inheritance from X-linked dominant inheritance in pedigree analysis is often difficult. Which of the following observations would be characteristic of autosomal dominant, but not of X-linked dominant inheritance?
An affected man has a normal son and an affected daughter.
An affected woman has both an affected daughter and an affected son.
An affected woman has both a normal daughter and an affected son.
An affected woman has an affected daughter and a normal daughter.
An affected man has an affected son and an affected daughter.
An affected man has an affected son and an affected daughter.
In adoption studies of genetic influence on traits, which assumption is most commonly violated?
Adopted persons have no more genes in common with their adoptive parents than do two randomly chosen persons.
Adopted persons have 50% of their genes in common with each of their biological parents.
Adopted persons share the same environment as their adoptive parents.
The environments of biological and adoptive families are not more alike than would be expected by chance.
None of the above examples represents a situation where an assumption is commonly violated.
The environments of biological and adoptive families are not more alike than would be expected by chance.
Adoption agencies carefully choose adoptive parents and may select a family that resembles the biological family.
Karyotypes are commonly used to detect _____________ abnormalities.
X-linked dominant
X-linked recessive
autosomal recessive
chromosome
autosomal dominant
chromosomes
Two children, a brother and his sister, are born with an autosomal recessive condition. They are believed to be the first two individuals in their extended family to have this disorder. What is the most likely genotypes for their parents?
The father is likely heterozygous for the disorder, and the mother is likely homozygous for the disorder.
The mother is likely heterozygous for the disorder, and the father is likely homozygous for the disorder.
The mother is likely homozygous for the normal genotype, and the father is likely heterozygous for the disorder.
The father is likely homozygous for the normal genotype, and the mother is likely heterozygous for the disorder.
Both parents are likely heterozygous for the disorder.
Both parents are likely heterozygous for the disorder.
Studies have been done on monozygotic twins that were separated soon after birth and raised in separate homes, often in different parts of the country. Many of these twins did not know that they had a twin until after they reached adulthood. For certain traits concordance values were found to be similar in these twins to values for monozygotic twins raised together. What can be concluded about these traits?
Genetic factors play little or no role in the expression of these traits.
Concordance values will also likely be similar for these traits in dizygotic twins raised apart.
Genetic factors and environmental factors likely play about equal roles in the expression of these traits.
Environmental factors that occurred after separation of the twins seemed to play little role in the expression of these traits.
These traits are likely to be caused by a small number of genes.
Environmental factors that occurred after separation of the twins seemed to play little role in the expression of these traits.
Amniocentesis and chorionic villus sampling are often used in __________ genetic testing.
newborn
proband
presymptomatic
prenatal
concordance
prenatal
Color blindness is inherited in humans as an X-linked recessive trait. What offspring are expected from a mating between a heterozygous woman and a phenotypically normal man?
None of the sons and all of the daughters will be color blind.
Half of the sons and none of the daughters will be color blind.
All of the sons and none of the daughters will be color blind.
None of the offspring are expected to be affected, but half of the daughters will be heterozygous for the color blind allele.
Half of the sons and half of the daughters will be color blind.
Half of the sons and none of the daughters will be color blind.
It passes from unaffected female to affected male to unaffected female.
Which of the following disorders is currently most commonly tested for in newborn screening programs?
hemophilia A
Tay-Sachs disease
phenylketonuria
asthma
epilepsy
Phenylketonuria
DNA analysis of cells obtained by amniocentesis or chorionic villus sampling
What can be concluded about a trait that shows a concordance of 100% in monozygotic twins and 50% in dizygotic twins?
is genetic.
About 25% of the basis of the trait is genetic, while 75% of the basis is environmental.
It is caused exclusively or almost exclusively by environmental factors.
About 50% of the basis of the trait is genetic, while 50% of the basis is environmental.
It is caused exclusively or almost exclusively by genetic factors.
About 25% of the basis of the trait is environmental, while 75% of the basis
It is caused exclusively or almost exclusively by genetic factors.
Which substance found in high concentrations in the blood of a pregnant woman might indicate that the fetus has a neural tube defect?
phenylalanine
alpha-fetoprotein
human chorionic gonadotropin
pregnancy-associated plasma protein
None of the above is correct.
alpha-fetoprotein
Which type of twins are the result of a single egg fertilized by a single sperm?
dizygotic
monozygotic
fraternal
identical
both monozygotic and identical are correct
both monozygotic and identical are correct
Which was the most important consideration in choosing genetic conditions for mandatory newborn screening?
the availability of heterozygote screening among adults so that the appropriate newborns to be tested can be identified
availability of effective treatments and early interventions
cost of the genetic test
severity of symptoms and associated medical costs
frequency of occurrence
availability of effective treatments and early interventions
Direct-to-consumer genetic tests have been of concern to public health officials because ________.
they can provide information about an individual’s genotype
they often involve DNA analysis, and an individual will have to develop the laboratory skills to do this analysis
they sometimes require that a blood sample be given
they can provide information about an individual’s ancestry
the results may be difficult to interpret without the involvement of appropriate genetic counseling
the results may be difficult to interpret without the involvement of appropriate genetic counseling
Newborns are generally screened for genetic diseases ________.
when a close relative is known to be affected
that are irreversible or untreatable disorders
that are fatal by one year of age
that are treatable or preventable
when heterozygous parents are affected
that are treatable or preventable
Fraternal=__zygotic
Dizygotic
Identical=___zygotic
Monozygotic
Even if geneticists could control human genetic crosses, the average waiting time to eventually collect F2 data from parental crosses would be about ____ years.
40
20
1 to 2
5
100
40
A four-year old boy and his two-year old brother share what proportion of their genes (alleles) compared to a set of male monozygotic twins?
Both the brothers and the twins share 1/2 of their genes.
The brothers share 1/2 of their genes, while the twins presumably have all (100%) identical genes.
The brothers share 1/8 of their genes, while the twins share 1/4 of their genes.
Both the brothers and the twins share 1/4 of their genes.
The boys share 1/4 of their genes, while the monozygotic twins share 1/2 of their genes.
The brothers share 1/2 of their genes, while the twins presumably have all (100%) identical genes.
If both members of a twin pair exhibit a trait of interest, the twins are said to be
concordant.
monozygotic.
fetal.
dizygotic.
discordant.
concordant
Interpreting many genetic tests, even with profession medical care provided, is often difficult because of which of the following?
All of the above make interpretation difficult.
the inability of many genetic tests to detect all the pathogenic mutations at a gene locus and to distinguish them from harmless mutations at the same locus.
influence of environmental factors that affect some complex conditions
presence of multiple mutations causing the same condition
incomplete penetrance for some pathogenic mutations
All of the above make interpretation difficult.
True or False? Y-linked traits are neither dominant nor recessive.
False
True
true
