front 1 A karyotype from peripheral blood shows a normal human diploid
chromosome count. How many chromosomes are present? | back 1 C. 46 |
front 2 A euploid embryo inherits equal chromosome sets from each parent.
Which distribution is correct? | back 2 A. 23 maternal, 23 paternal |
front 3 In humans, the number of autosomal chromosome pairs is: | back 3 D. 22 pairs |
front 4 A couple asks who determines genetic sex at conception. The father
can transmit: | back 4 B. X or Y |
front 5 A variant disrupts a DNA segment that encodes a functional product.
This segment is a: | back 5 B. Gene |
front 6 A report states “mutation at 7q31.” This describes a
chromosomal: | back 6 D. Locus |
front 7 Two siblings share the same locus but differ in sequence at that
site. Each version is an: | back 7 A. Allele |
front 8 A diploid individual’s genotype at one locus includes: | back 8 C. Two alleles |
front 9 A pedigree shows many affected males with carrier females. Best
explanation? | back 9 D. Single X in males |
front 10 A disorder appears in both sexes each generation with no sex bias.
This pattern best fits: | back 10 C. Autosomal recessive |
front 11 A meiotic error causes sister chromatids to fail separation. This
is: | back 11 B. Nondisjunction |
front 12 A newborn has an abnormal chromosome number due to meiotic
segregation failure. This is: | back 12 C. Aneuploidy |
front 13 Prenatal testing reveals autosomal aneuploidy. The most common
outcome is: | back 13 A. Spontaneous abortion or disease |
front 14 Which is NOT a chromosomal structural alteration? | back 14 D. Nondisjunction |
front 15 A disorder appears in both sexes each generation with no sex bias.
This pattern best fits: | back 15 C. Autosomal dominant |
front 16 A drug increases transcription by loosening chromatin via histone
tail changes. Which mechanism? | back 16 C. Histone acetylation |
front 17 A tumor shows stable DNA sequence but reduced gene expression via
promoter modification. Most consistent with: | back 17 D. Cytosine methylation |
front 18 A syndrome shows parent-of-origin effects without nucleotide change.
This is: | back 18 A. Imprinting |
front 19 A disorder differs depending on whether the allele came from mother
or father. This reflects imprinting being: | back 19 C. Sex-specific |
front 20 In a somatic lineage, an imprint typically: | back 20 B. Persists in progeny cells |
front 21 During gametogenesis, imprint marks are: | back 21 A. Reset |
front 22 A researcher uses a population model to infer allele frequencies from
genotype frequencies. This is: | back 22 D. Hardy–Weinberg equilibrium |
front 23 Hardy–Weinberg methods are best suited to analyze: | back 23 B. Autosomal and XLR disorders |
front 24 A patient’s condition reflects multiple genes plus environment. This
is: | back 24 C. Multifactorial disease |
front 25 A pedigree shows progressive severity across generations due to
repeat expansion. Inheritance is usually: | back 25 A. Autosomal dominant |
front 26 Earlier onset and worsening symptoms in later generations most
directly correlates with: | back 26 D. Increasing repeat number |
front 27 A mutation removes cell-cycle “brakes,” enabling uncontrolled
proliferation. The gene class is: | back 27 C. Tumor suppressor genes |
front 28 Which is an epigenetic modification mechanism? | back 28 B. Histone phosphorylation |
front 29 A pedigree shows vertical transmission of retinoblastoma-like cancer
predisposition. Which statement best fits tumor suppressor
inheritance? | back 29 C. Autosomal dominant; recessive mechanism |
front 30 In a familial cancer workup, a tumor shows deletion of the remaining
wild-type allele at a locus. This is: | back 30 A. Loss of heterozygosity |
front 31 A prenatal karyotype shows 47 total chromosomes. This abnormality is
best termed: | back 31 D. Aneuploidy |
front 32 A newborn has streak ovaries and webbed neck; karyotype: 45,X.
Diagnosis? | back 32 B. Turner syndrome |
front 33 A fetus has 47,XY,+21. The diagnosis is: | back 33 D. Down syndrome |
front 34 A lab orders a test to visualize chromosomes and detect trisomies and
translocations. Best test? | back 34 A. Karyotype |
front 35 For karyotyping, cells are arrested when chromosomes are maximally
visible. This stage is: | back 35 B. Mitotic metaphase |
front 36 A genetics student asks when crossing over occurs. Correct timing
is: | back 36 C. After replication, before metaphase I |
front 37 A traits lecture defines heritability. Which description is
correct? | back 37 A. Genetic and environmental components |
front 38 A trait has “genetic component 100%.” This implies: | back 38 D. No environmental influence on phenotype |
front 39 A trait has “genetic component 10%.” This implies phenotype is
mainly: | back 39 B. Environmental |
front 40 In counseling, “penetrance” refers to: | back 40 C. Probability phenotype expressed |
front 41 A mutation has 100% penetrance. This means: | back 41 A. All carriers express disease |
front 42 A family shows incomplete penetrance. Which factor can explain
penetrance <100%? | back 42 B. Modifier genes or epigenetics |
front 43 Two relatives carry the same mutant allele and both are affected, but
one is mild and one is severe. This is: | back 43 D. Variable expressivity |
front 44 A disorder shows 100% penetrance, yet affected relatives have
different clinical pictures. This best reflects: | back 44 A. Variable expressivity |
front 45 A clinician asks why expressivity varies within families. Most
consistent causes are: | back 45 C. Environment and modifier genes |
front 46 Which disorder is a classic example of variable expressivity? | back 46 B. Marfan syndrome |
front 47 A heterozygous affected parent has an autosomal dominant disorder.
Risk each child is affected: | back 47 D. 50% |
front 48 A patient has café-au-lait spots and neurofibromas (Neurofibromatosis
type 1). Inheritance pattern is most classically: | back 48 C. Autosomal dominant |
front 49 Short-limbed dwarfism with FGFR involvement suggests: | back 49 A. Achondroplasia |
front 50 An adult develops progressive neurodegeneration with a family history
across generations; the listed autosomal dominant example is: | back 50 B. Huntington disease type 2 |
front 51 Achondroplasia is caused by mutation in which gene class? | back 51 C. FGF receptor gene |
front 52 Why is mitotic metaphase optimal for karyotyping? | back 52 D. Chromosomes most condensed, easily seen |
front 53 A patient develops progressive chorea and cognitive decline. Testing
reveals a triplet-repeat expansion in which gene? | back 53 B. HTT |
front 54 A tall patient with lens subluxation has a mutation in a fibrous
protein. The gene product is: | back 54 A. Fibrillin |
front 55 A child with café-au-lait spots has a mutation in a GTPase-activating
protein. The mutated gene is: | back 55 C. NF1 |
front 56 Two carrier parents have a child. In autosomal recessive inheritance,
expected outcomes are: | back 56 A. 25% affected |
front 57 A drug increases transcription by loosening chromatin via histone
tail changes. Which mechanism? | back 57 C. Histone acetylation |
front 58 A child has generalized hypopigmentation due to loss of melanin
synthesis. Defective enzyme: | back 58 B. Melanocyte tyrosinase |
front 59 A newborn has recurrent lung infections and pancreatic insufficiency.
The mutated protein is: | back 59 B. CFTR |
front 60 A screening test suggests PKU. The most common deficiency is: | back 60 B. Phenylalanine hydroxylase |
front 61 A patient has sickle cell disease. The causative mutation is: | back 61 A. E6V in β-globin |
front 62 A pedigree shows affected males only, with no male-to-male
transmission. This suggests: | back 62 C. X-linked recessive |
front 63 In X-linked recessive disorders, females are typically: | back 63 A. Asymptomatic |
front 64 A conceptus has monosomy of chromosome 7. The expected outcome
is: | back 64 B. Embryonic lethal |
front 65 Trisomies most compatible with limited survival involve: | back 65 D. 13, 18, 21 |
front 66 To balance gene expression in females, one X chromosome
undergoes: | back 66 B. Inactivation and condensation |
front 67 The condensed inactive X chromosome in female somatic cells is
called: | back 67 B. Barr body |
front 68 Which is an X-linked recessive disorder? | back 68 A. Hemophilia A |
front 69 Hemophilia A results from mutation in: | back 69 B. Factor VIII |
front 70 Duchenne muscular dystrophy is most often due to: | back 70 B. Large deletions in DMD |
front 71 Red-green color blindness most directly reflects: | back 71 B. Cone dysfunction |
front 72 The most common inborn error of the urea cycle is: | back 72 B. OTC deficiency |
front 73 A child has exercise intolerance and lactic acidosis. A pathogenic
mtDNA mutation most directly impairs: | back 73 B. Oxidative phosphorylation |
front 74 A muscle biopsy shows mixed normal and mutant mtDNA within the same
cell. This is: | back 74 D. Heteroplasmy |
front 75 A cell’s mitochondria all carry the same mtDNA genome (normal or
mutant). This is: | back 75 A. Homoplasmy |
front 76 A pedigree shows only affected mothers transmit a disorder.
Mitochondria are inherited from the: | back 76 C. Mother |
front 77 A woman with a mitochondrial disorder has children. Expected
penetrance among her children is: | back 77 A. All children affected |
front 78 A man with a mitochondrial disorder has children with an unaffected
partner. His children are most likely: | back 78 D. Unaffected |
front 79 Two siblings from the same affected mother have different severities.
Best explanation: | back 79 C. Variable mutant mitochondria load |
front 80 A mitochondrial disorder most prominently affects tissues with: | back 80 B. High energy requirement |
front 81 A young adult has painless central vision loss consistent with
Leber’s hereditary optic neuropathy (LHON). The typical genetic lesion
is: | back 81 D. Mitochondrial protein-gene mutation |
front 82 A patient has MERRF myoclonic seizures and ragged-red fibers. The
lesion most classically involves: | back 82 A. Mitochondrial tRNA gene mutation |
front 83 A patient has stroke-like episodes and lactic acidosis (MELAS). The
mutation most often affects: | back 83 C. Mitochondrial tRNA gene mutation |
front 84 A teen has myopathy, cerebellar findings, and cardiomyopathy
(Kearns–Sayre). Most likely mechanism: | back 84 B. mtDNA deletion |
front 85 A child has hypophosphatemic rickets with an X-linked dominant
pedigree. The implicated gene is: | back 85 A. PHEX |
front 86 A girl has blistering rash evolving into hyperpigmented streaks;
males in family die early. The causal gene is: | back 86 D. IKBKG |
front 87 Incontinentia pigmenti type 1 is often: | back 87 B. Fatal in males |
front 88 The IKBKG gene product primarily regulates a family of: | back 88 C. Transcription factors |
front 89 A trisomy results from a meiotic error. The process is: | back 89 A. Nondisjunction |
front 90 Nondisjunction is best defined as: | back 90 B. Unequal sorting in meiosis I/II |
front 91 Which is a chromosomal structural alteration? | back 91 C. Inversion |
front 92 An inversion involves: | back 92 A. Two breaks; segment inverted |
front 93 A duplication involves: | back 93 D. Duplicated segment inserted same chromosome |
front 94 A disorder caused by loss of a small chromosomal segment is best
termed: | back 94 C. Microdeletion syndrome |
front 95 A prenatal report notes an “insertion” without net DNA loss. Which
description best fits an insertion? | back 95 C. Segment inserted into another chromosome |
front 96 A cytogenetics lab suspects an isochromosome. Which structure is most
characteristic? | back 96 A. Two identical p arms or q arms |
front 97 In an isochromosome, the two arms are: | back 97 D. Genetically identical to each other |
front 98 A syndrome is linked to a small chromosomal deletion with complex,
consistent phenotype. “Microdeletion” typically means: | back 98 B. Deletion under 5 megabases |
front 99 A child’s phenotype suggests a microdeletion syndrome; standard
karyotype is normal. A test often needed to localize the deletion
is: | back 99 A. FISH |
front 100 A clinician suspects an even smaller deletion that FISH can miss.
Which method is more sensitive for microdeletions? | back 100 D. Array-based genomic hybridization |
front 101 Two main categories of chromosomal translocations are: | back 101 B. Robertsonian and reciprocal |
front 102 A “balanced reciprocal translocation” is best described as: | back 102 C. Mutual exchange between two chromosomes |
front 103 A balanced reciprocal translocation is “balanced” because: | back 103 D. No net genetic material loss |
front 104 A tall man has infertility and small testes. Which karyotype is most
likely? | back 104 B. 47,XXY |
front 105 A patient has short stature and amenorrhea; karyotype shows monosomy
X. Diagnosis? | back 105 A. Turner syndrome |
front 106 A newborn has cleft lip/palate and polydactyly; karyotype is trisomy
13. Syndrome? | back 106 C. Patau syndrome |
front 107 A neonate with low birth weight and a small, abnormally shaped head
has trisomy 18. Syndrome? | back 107 B. Edwards syndrome |
front 108 A child has hypotonia, characteristic facies, and congenital heart
disease; karyotype shows +21. Syndrome? | back 108 D. Down syndrome |
front 109 A female has learning difficulties but no major physical anomalies;
karyotype is 47,XXX. Diagnosis? | back 109 C. Triple-X syndrome |
front 110 A boy has some learning/behavioral problems; karyotype is 47,XYY.
Diagnosis? | back 110 A. XYY syndrome |
front 111 Which aneuploidy is associated with increased leukemia risk? | back 111 B. Down syndrome |
front 112 Severe CNS anomalies with polydactyly strongly suggests: | back 112 D. Patau syndrome |
front 113 Low birth weight with heart defects and small malformed head most
strongly suggests: | back 113 C. Edwards syndrome |
front 114 Turner syndrome is especially common among: | back 114 A. Miscarriages and stillbirths |