Deck 6: Genetics

Question 1

Genes that are located at the same level in homologous chromosomes and that dictate the same functions or characteristics are called:

A) consanguineous.
B) chromatids.
C) alleles.
D) precocious.

Answer 1

alleles.

Question 2

During transcription:

A) polypeptides form an amino acid, and one or more amino acids form a protein.
B) amino acids form a polypeptide, and one or more polypeptides form a protein.
C) proteins form a polypeptide, and one or more polypeptides form an amino acid.
D) amino acids form a protein, and one or more proteins form a polypeptide.

Answer 2

amino acids form a polypeptide, and one or more polypeptides form a protein.

Question 3

A karyotype:

A) may use arginine to arrest the mitosis of leukocytes at metaphase.
B) may use colchicine to arrest the mitosis of leukocytes at metaphase.
C) may use colchicine to arrest the mitosis of red blood cells at anaphase.
D) is used to evaluate molecular abnormalities in chromosomes.

Answer 3

may use colchicine to arrest the mitosis of leukocytes at metaphase.

Question 4

Features of second meiosis include:

A) a replication of DNA before initiation.
B) essentially a mitotic division in which each chromosome splits longitudinally.
C) formation of four cells from the parent cell.
D) the formation of 2nDNA.

Question 5

The correct order for the stages of mitosis is:

A) prophase, anaphase, metaphase, telophase.
B) prophase, metaphase, anaphase, telophase.
C) prophase metaphase, telophase, anaphase.
D) metaphase, prophase, telophase, anaphase.

Question 6

In DNA a sequence of thymine, adenine, and cytosine (TAC) is always matched by:

A) adenine, cytosine, and guanine (ACG).
B) guanine, adenine, and cytosine (GAC).
C) adenine, thymine, and guanine (ATG).
D) a five-carbon sugar and a phosphate.

Question 7

A codon in DNA is formed by a sequence of _________ bases.

A) two
B) three
C) four
D) six

Question 8

The gap 2 (G₂) phase of mitosis:

A) begins when mitotic division ends.
B) ends when mitotic division begins.
C) precedes the S phase.
D) is when replication of DNA takes place.

Question 9

Ribonucleic acid (RNA) contains uracil rather than the base ___________ found in DNA.

A) adenine
B) guanine
C) cytosine
D) thymine

Question 10

Which of the following types of RNA carries the message for transcription of DNA to ribosomes in the cytoplasm?

A) mRNA
B) tRNA
C) rRNA
D) hnRNA

Question 11

Which of the following statements is true regarding gross chromosomal abnormalities involving alterations in the number of chromosomes?

A) An aneuploid is a complete second set of chromosomes, meaning a total of 46.
B) A polyploid is any number of chromosomes that do not represent an exact multiple of the total chromosome complement.
C) An euploid is a complete second set of chromosomes, meaning a total of 46.
D) An aneuploid may be represented by trisomy and monosomy.

Question 12

Which of the following statements is correct concerning chromosomes?

A) They are located in the cytoplasm of the cell.
B) Mature germ cells (ova and spermatozoa) contain 46 chromosomes.
C) Chromosomes can only be seen clearly under a microscope when the nucleus and cell are dividing.
D) Chromosomes contain RNA, which directs the production of amino acids, polypeptides, and proteins by the cell.

Question 13

Most cases of Down syndrome are associated with:

A) maternal consumption of alcohol.
B) late maternal age at the time of conception.
C) estrogen supplements.
D) inhalation of vapors from volatile substances.

Question 14

The contact between a chromatid of one chromosome and a chromatid of the other chromosome of a pair, where crossing over and exchange of chromosome segments occurs, is called the:

A) first meiosis.
B) second meiosis.
C) chiasmata.
D) interpolation.

Question 15

Primitive germ cells:

A) have 23 chromosomes and are called diploid.
B) have 46 chromosomes and are called haploid.
C) have 23 chromosomes and are called haploid.
D) have 46 chromosomes and are called diploid.

Question 16

Which of the following statements is true of oogenesis?

A) Oogenesis starts around the time of puberty.
B) The second meiosis is completed at the beginning of ovulation.
C) Nondisjunction is more prevalent in male spermatogenesis than in female oogenesis.
D) The older the woman, the greater the chance of shedding a trisomic ovum.

Question 17

If both loci for blood are AO,:

A) the person is said to have blood group O.
B) the person is said to have blood group A.
C) the person would be homozygous.
D) the characteristic is recessive.

Question 18

After metaphase of the first meiotic division:

A) the chromosomes split at the centromere and separate from one another.
B) the chromosomes do not split at the centromere but separate from one another.
C) each member of the pair migrates to one of the new cells, each of which contains 46 chromosomes but twice the final amount of DNA.
D) each member of the pair migrates to one of the new cells, each of which contains 23 chromosomes but half the final amount of DNA.

Question 19

Chromosomes line up at the equatorial plate during the __________ stage of mitosis.

A) Telophase
B) Metaphase
C) Prophase
D) Anaphase

Question 20

According to the Lyon hypothesis, during the early period of embryonic development:

A) the genetic activity of both of the X chromosomes in each cell of a female embryo is inactivated.
B) the genetic activity of one of the X chromosomes in each cell of a female embryo is inactivated.
C) the genetic activity of the Y chromosome in each cell of a male embryo is inactivated.
D) the inactivated chromosome forms a structure known as the pronucleus.

Question 21

Cyclic neutropenia:

A) is characterized by episodes that generally persist for 21 to 27 days.
B) is characterized by oral manifestations consisting of severe ulcerative gingivitis or gingivostomatitis.
C) is caused by a deletion on the long arm of chromosome 11 regions 14-21.
D) is inherited as an autosomal recessive.

Question 22

Which of the following disorders affecting the jaw bones and facies is characterized by fusion of the anterior portion of the maxillary gingiva to the upper lip from canine to canine?

A) Gardner syndrome
B) Mandibulofacial dysostosis
C) Ellis-Van Creveld syndrome
D) Cherubism

Question 23

A patient with unilateral or bilateral aplasia of the clavicles:

A) will have hyperplastic paranasal sinuses.
B) will have a short and wide neck.
C) will have a mushroom shape of the cranium because of premature closure of fontanelles.
D) will be able to approximate his or her shoulders to the midline.

Question 24

The majority of patients with Turner syndrome have:

A) a male phenotype and 47 chromosomes.
B) a female phenotype and 46 chromosomes.
C) a female phenotype and 45 chromosomes.
D) a male phenotype and 44 chromosomes.

Question 25

Which of the following clinical syndromes caused by gross chromosomal abnormalities is associated with bilateral cleft lip and palate, microphthalmia or anophthalmia, and polydactyly?

A) Trisomy 13
B) Trisomy 21
C) Turner syndrome
D) Klinefelter syndrome

Question 26

Which of the following statements is true concerning hemophilia A?

A) It is inherited as an X-linked dominant condition.
B) It is inherited as a Y-linked recessive condition.
C) All X chromosomes are abnormal in the female carrier.
D) Female carriers tend to bleed more than usual after extraction of teeth or scaling and curettage.

Question 27

For parents who are carriers of the same recessive trait, the chance of having an affected child is __%.

A) 0
B) 25
C) 50
D) 100

Question 28

Cherubism:

A) is inherited as an autosomal-dominant disease with marked penetrance in females and variable expressivity and incomplete penetrance in males.
B) most frequently involves the maxilla.
C) is characterized by a unilateral facial deformity.
D) reveals a typical "soap-bubble" or multilocular appearance on radiographs.

Question 29

___________________ is an inherited disorder affecting the gingiva and periodontium, which is characterized by hyperkeratosis of the palms of the hands and soles of the feet.

A) Cyclic neutropenia
B) Papillon-Lefèvre syndrome
C) Gingival fibromatosis
D) Laband syndrome

Question 30

A karyotype containing XXXY indicates ____________ syndrome.

A) Down
B) Klinefelter
C) Turner
D) Cri du chat

Question 31

Which of the following statements is true regarding management of patients with cyclic neutropenia?

A) Preventive antibiotic therapy is instituted to protect against secondary opportunistic infections.
B) Treatment should be done when the circulating neutrophil count is low to reduce the risk of complications such as gingival hemorrhage and secondary infection.
C) Dental hygiene care increases the risk of opportunistic infections in patients with cyclic neutropenia.
D) Patients are treated periodically with vitamin D to reduce symptoms.

Question 32

For autosomal-dominant inheritance:

A) males will be affected more often than females.
B) the risk of having an affected offspring is 25% when a person has a gene for the condition.
C) All of the offspring could be affected by a condition that is transmitted by autosomal-dominant inheritance.
D) an individual can carry a gene with a dominant effect without presenting any clinical manifestations.

Question 33

Gingival and periodontal disease has been reported in __% of individuals with Down syndrome.

A) 10
B) 25
C) 50
D) 90

Question 34

The areas of bony radiolucency seen in cherubism:

A) resemble a central giant cell granuloma when seen under the microscope.
B) occur in place of the teeth, and radiographs will reveal a complete anodontia.
C) will increase in size as the patient matures, even until the seventh or eighth decade of life.
D) will resolve, leaving the patient without any sign of facial deformity later in life.

Question 35

For autosomal-dominant inheritance, ___________ pertains to the degree to which an individual is affected.

A) penetrance
B) expressivity
C) heterogeneity
D) consanguinity

Question 36

A man's X chromosome is transmitted to:

A) none of his daughter's and none of his son's.
B) none of his daughter's and all of his son's .
C) all of his daughter's and none of his son's.
D) all of his daughter's and all of his son's.

Question 37

A mother who is a carrier of an X-linked recessive trait has a 50% risk of having:

A) an affected son or daughter.
B) a carrier son or daughter.
C) an affected son or a carrier daughter.
D) a carrier son or an affected daughter.

Question 38

A patient with Ellis-Van Creveld syndrome will:

A) show polydactyly on the radial side of the forearm.
B) be a midget.
C) lack an anterior maxillary vestibular sulcus.
D) lack a posterior mandibular sulcus.

Question 39

Blood group ___ is an example of gene codominance.

A) O
B) A
C) B
D) AB

Question 40

Murray-Puretic-Drescher syndrome is also known as:

A) cherubism.
B) gingival fibromatosis with multiple hyaline fibromas.
C) gingival fibromatosis with hypertrichosis, epilepsy, and mental retardation syndrome.
D) Laband syndrome.

Question 41

The _____________ type of amelogenesis imperfecta is characterized by tooth enamel that does not develop to a normal thickness because of failure of the ameloblasts to lay down enamel matrix properly.

A) hypoplastic
B) hypocalcified
C) hypomaturation
D) hypoplastic-hypomaturation

Question 42

Oral manifestations of nevoid basal cell carcinoma syndrome consist of multiple cysts of the jaws that are:

A) central giant cell granulomas.
B) peripheral giant cell granulomas.
C) odontogenic keratocysts.
D) calcifying epithelial odontogenic tumors.

Question 43

Multiple mucosal neuroma syndrome includes multiple mucosal neuromas, medullary carcinoma of the thyroid gland, and:

A) telangiectases.
B) pheochromocytoma.
C) gastrointestinal polyposis.
D) blue sclera.

Question 44

Which of the following statements is true of the hereditary opalescent form of dentinogenesis imperfecta?

A) It is associated with taurodontic teeth.
B) Teeth have bulbous crowns with a color that varies from opalescent brown to brownish blue.
C) Large pulp chambers and root canals are seen on radiographs.
D) Roots are long and thick with periapical radiopacities.

Question 45

Radicular dentin dysplasia is characterized by teeth with __________ crowns and __________ roots.

A) normal; normal
B) normal; abnormal
C) abnormal; normal
D) abnormal; abnormal

Question 46

Cases of facial clefting occur in about 1 in ______ births.

A) 80
B) 200
C) 800
D) 2000

Question 47

Snow-capped amelogenesis imperfecta is a type of:

A) type I: hypoplastic amelogenesis imperfecta.
B) type II: hypocalcified amelogenesis imperfecta.
C) type III: hypomaturation amelogenesis imperfecta.
D) type IV: hypoplastic-hypomaturation amelogenesis imperfecta.

Question 48

Which of the following syndromes is characterized by multiple melanotic macular pigmentations of the skin and mucosa, which are associated with gastrointestinal polyposis?

A) Osler-Rendu-Parkes Weber syndrome.
B) Van der Woode syndrome
C) Gorlin syndrome
D) Peutz-Jeghers syndrome

Question 49

The basic defect responsible for osteogenesis imperfecta is produced by different mutations affecting the genes that encode for type I collagen, resulting in:

A) lack of otic ossicles.
B) unilateral or bilateral aplasia or hypoplasia of clavicles.
C) overgrowth of cortical bone in the midline of the palate.
D) abnormally formed bones that fracture easily.

Question 50

Hard, dense, cortical bone on the buccal aspect of the alveolar ridge by tooth number 14 would be termed a:

A) radiolucent torus palatinus.
B) radiopaque torus mandibularis.
C) radiopaque exostosis.
D) radiolucent exostosis.

Question 51

____________ is a constant feature of mandibulofacial dysostosis.

A) Hypertrichosis
B) Deafness
C) Hypertelorism
D) Kyphoscoliosis

Question 52

A patient with ______________________ will have a mouth that appears fishlike, with downward sloping of the lip commissures.

A) osteogenesis imperfecta
B) mandibulofacial dysostosis
C) cherubism
D) cleidocranial dysplasia

Question 53

The primary dentition of a patient with coronal dentin dysplasia will appear:

A) normal.
B) opaque with an amber color.
C) translucent with an amber color.
D) translucent with a blue color.

Question 54

White sponge nevus is characterized by a white, corrugated, soft, folding oral mucosa always affecting _______ mucosa.

A) attached
B) lingual
C) buccal
D) tonsillar

Question 55

Intestinal polyps seen with Peutz-Jeghers syndrome are:

A) associated with inevitable malignant transformation into adenocarcinomas.
B) hamartomas.
C) caused by the adenomatous polyposis coli (APC) gene located on the long arm of chromosome 5.
D) associated with osteomas in various bones, especially the frontal bones, mandible, and maxilla.

Question 56

Which of the following syndromes is characterized by intestinal polyps, which become malignant at age 30 and after?

A) Osteogenesis imperfecta
B) Nevoid basal cell carcinoma syndrome
C) Mandibulofacial dysostosis
D) Gardner syndrome

Question 57

Early diagnosis of pheochromocytoma is imperative because of the high malignant potential of:

A) squamous cell carcinoma.
B) basal cell carcinoma.
C) thyroid carcinoma.
D) osteogenic sarcoma.

Question 58

Neurofibromatosis of Von Recklinghausen is characterized by:

A) multiple neurofibromas appearing as macules of various sizes.
B) inevitable malignant transformation.
C) oral involvement in about 90% of patients.
D) café au lait pigmentation of skin in 90% of patients.

Question 59

Telangiectasias of the oral mucosa for a patient with hereditary hemorrhagic telangiectasia will be especially prominent on the:

A) tip and anterior dorsum of the tongue.
B) palate.
C) gingiva.
D) buccal mucosa.

Question 60

The basic defect found with radicular dentin dysplasia seems to lie in the:

A) stellate reticulum.
B) epithelial root sheath.
C) stratum intermedium.
D) dental papilla.

Question 61

Frontal bossing, depressed nasal bridge, protuberant lips, and almost complete lack of scalp hair is characteristic of a person with:

A) hypophosphatemic vitamin D-resistant rickets.
B) hypophosphatasia.
C) hypohidrotic ectodermal dysplasia.
D) dentin dysplasia.

Question 62

_____________________ is characterized by very large, pyramid-shaped molars with large pulp chambers.

A) Amelogenesis imperfecta
B) Dentinogenesis imperfecta
C) Taurodontism
D) Dentin dysplasia

Question 63

Hypohidrotic ectodermal dysplasia is characterized by:

A) hypodontia, hypotrichosis, and hypohidrosis.
B) hyperdontia, hypotrichosis, and hypohidrosis.
C) hypodontia, hypertrichosis, and hyperhidrosis.
D) hyperdontia, hypertrichosis, and hyperhidrosis.

Question 64

Hypophosphatasia is characterized by:

A) an increase in serum alkaline phosphatase levels.
B) abnormal formation of enamel and dentin.
C) exfoliation of teeth without evidence of periodontal or gingival disease.
D) an autosomal-dominant inheritance pattern.

Question 65

Characteristic radiographic oral findings of hypophosphatemic vitamin D-resistant rickets include:

A) obliterated pulp chambers.
B) large pulp chambers with very long pulp horns.
C) normal pulp chambers with nonexistent roots.
D) large pulp chambers with nonexistent pulp horns.

Question 66

Pegged or absent maxillary lateral incisors:

A) affects the secondary but not primary dentition.
B) has a prevalence of 10% in the white population.
C) is accompanied by congenitally lacking premolar teeth in 10% to 20% of the population.
D) is generally an autosomal-recessive trait with variable expressivity.