chapter 10

Question 1

What was the most common birth defect caused by maternal rubella infection?
A. Heart defect
B. Blindness
C. Hearing loss
D. Cleft palate

Answer 1

C. Hearing loss - Hearing/deafness is the most common defect caused by rubella infection during the first trimester.

Question 2

Which birth defect is most associated with thalidomide exposure during pregnancy?
A. Cleft palate
B. Phocomelia
C. Hydrocephaly
D. Spina bifida

Answer 2

B. Phocomelia - Thalidomide exposure caused phocomelia, or shortened limbs, especially in the 1960s.

Question 3

Which human gene is commonly altered by exposure to tobacco smoke?
A. CYP2E1
B. AHRR
C. TP53
D. GSTM1

Answer 3

B. AHRR - AHRR (aryl-hydrocarbon receptor repressor) is frequently epigenetically altered by tobacco smoke.

Question 4

What synthetic retinoid is associated with developmental toxicity, despite strict regulations?
A. Retinol
B. Isotretinoin
C. Retinaldehyde
D. Beta-carotene

Answer 4

B. Isotretinoin - Isotretinoin (Accutane), a synthetic retinoid, remains teratogenic even with strong controls.

Question 5

Which antiepileptic drug is associated with teratogenic effects?
A. Acetaminophen
B. Phenytoin
C. Aspirin
D. Diazepam

Answer 5

B. Phenytoin - Antiepileptic drugs like phenytoin can cause birth defects and developmental issues.

Question 6

Which synthetic estrogen caused trans-placental cancer in offspring?
A. Ethinyl estradiol
B. Diethylstilbestrol
C. Estradiol
D. Progesterone

Answer 6

B. Diethylstilbestrol - This synthetic estrogen caused clear cell adenocarcinoma of the vagina in young females.

Question 7

Which of the following describes the process of gametogenesis?
A. Fusion of sperm and egg to form a zygote
B. Process leading to formation of haploid germ cells
C. Formation of the three germ layers
D. Differentiation of the reproductive tract

Answer 7

B. Process leading to formation of haploid germ cells
Explanation: Gametogenesis refers to the process culminating in the formation of the egg and sperm (haploid germ cells).

Question 8

What is the primary outcome of the fusion of egg and sperm during fertilization?
A. Formation of blastocyst
B. Gastrulation
C. Formation of zygote
D. Differentiation of tissues

Answer 8

C. Formation of zygote
Explanation: A zygote is formed when the egg and sperm fuse during fertilization.

Question 9

Which of the following mechanisms is NOT involved in genomic imprinting?
A. Cytosine methylation
B. Histone methylation
C. Non-coding RNAs
D. RNA splicing

Answer 9

D. RNA splicing
Explanation: Imprinting involves cytosine methylation, histone methylation, and non-coding RNAs, but not RNA splicing.

Question 10

When is the lowest total genomic methylation observed during development?
A. Gametogenesis
B. Gastrulation
C. After formation of zygote
D. Fetal period

Answer 10

C. After formation of zygote
Explanation: There is marked demethylation after the zygote is formed, resulting in the lowest total genomic methylation.

Question 11

What occurs during gastrulation?
A. Increase in cell number only
B. Differentiation of reproductive tract
C. Formation of three germ layers
D. Formation of blastocyst

Answer 11

C. Formation of three germ layers
Explanation: Gastrulation is when the ectoderm, mesoderm, and endoderm germ layers form.

Question 12

Organogenesis in humans primarily occurs during which weeks of gestation?
A. 1st to 3rd
B. 3rd to 8th
C. 9th to 12th
D. 13th to 16th

Answer 12

B. 3rd to 8th
Explanation: Organogenesis takes place from the 3rd to 8th week of human gestation.

Question 13

Which of the following is most likely to be affected by chemical exposure during the fetal period?
A. Limb malformations
B. Brain and eye defects
C. Morphological defects
D. Growth and functional development

Answer 13

D. Growth and functional development
Explanation: Chemical exposure during the fetal period is more likely to affect growth and function than morphology.

Question 14

Chemicals that cause fetal death but not malformations are categorized as:
A. Teratogenic
B. Embryotoxic or embryolethal
C. Epigenetic modifiers
D. Hormone disruptors

Answer 14

B. Embryotoxic or embryolethal
Explanation: Chemicals producing fetal death are considered embryotoxic or embryolethal, not teratogenic.

Question 15

Which of the following best defines an endocrine disruptor?
A. A drug that enhances immune response
B. An agent that mimics insulin action
C. A substance that interferes with hormonal regulation
D. A chemical that repairs DNA damage

Answer 15

C. A substance that interferes with hormonal regulation
Explanation: Endocrine disruptors interfere with hormone production, metabolism, or signaling, affecting developmental processes.

Question 16

Which of the following is a xenoestrogen linked to vaginal adenocarcinoma in female offspring?
A. Tamoxifen
B. Diethylstilbestrol (DES)
C. Bisphenol A
D. Estradiol

Answer 16

B. Diethylstilbestrol (DES)
Explanation: DES is a synthetic estrogen shown to cause cancer and reproductive abnormalities in exposed female offspring.

Question 17

Which compound is commonly found in plastics and acts as a weak estrogen?
A. Finasteride
B. Kepone
C. Bisphenol A (BPA)
D. Methoxychlor

Answer 17

C. Bisphenol A (BPA)
Explanation: BPA is a plasticizer with estrogenic activity linked to developmental effects.

Question 18

Which of the following is a fungicide with antiandrogenic effects that also shows transgenerational epigenetic effects?
A. Vinclozolin
B. Methoxychlor
C. Flutamide
D. Coumestrol

Answer 18

A. Vinclozolin
Explanation: Vinclozolin is an antiandrogenic fungicide known for disrupting male reproductive development and affecting future generations.

Question 19

Which of these inhibits 5α-reductase and is used in treating enlarged prostate?
A. Flutamide
B. Tamoxifen
C. Finasteride
D. Coumestrol

Answer 19

C. Finasteride
Explanation: Finasteride blocks conversion of testosterone to DHT, affecting male development when exposed prenatally.

Question 20

Which gene’s disruption by smoking-related methylation is consistently reported in epigenetic studies?
A. BRCA1
B. AHRR
C. PPARγ
D. CYP1A1

Answer 20

B. AHRR
Explanation: AHRR is frequently altered by epigenetic changes linked to environmental exposures like tobacco smoke.

Question 21

Which phytoestrogen found in soy is known for its estrogen-like effects?
A. Coumestrol
B. Genistein
C. Vinclozolin
D. Kepone

Answer 21

B. Genistein
Explanation: Genistein is a plant-derived estrogen found in soy that can bind to estrogen receptors and alter development.

Question 22

Which endocrine disruptor affects thyroid hormone and is used in electrical transformers?
A. PCB
B. Methoxychlor
C. Tamoxifen
D. DES

Answer 22

A. PCB
Explanation: Polychlorinated biphenyls (PCBs) disrupt thyroid hormones and are known for neurodevelopmental toxicity.

Question 23

Which antiestrogen is used in breast cancer treatment?
A. Tamoxifen
B. Genistein
C. Clomiphene
D. Estradiol

Answer 23

A. Tamoxifen
Explanation: Tamoxifen is a selective estrogen receptor modulator used to block estrogen in breast tissue.

Question 24

Which hormone-related test parameter is used to detect feminization in male rodents?
A. Sperm chromatin assay
B. Anogenital distance (AGD)
C. Liver enzyme profile
D. Bone mineral density

Answer 24

B. Anogenital distance (AGD)
Explanation: AGD is shortened in males exposed to antiandrogens and is a biomarker of androgen disruption.

Question 25

Which of the following is NOT a known mechanism of teratogenicity? A. Mutations B. Enzyme activation C. Altered mitosis D. Cell death

Answer 25

B. Enzyme activation Explanation: Enzyme inhibition, not activation, is commonly associated with reduced cell proliferation and teratogenicity.

Question 26

Which enzyme is inhibited by acetazolamide, leading to teratogenic effects? A. Thymidylate synthase B. Carbonic anhydrase C. Aromatase D. Monoamine oxidase

Answer 26

B. Carbonic anhydrase Explanation: Acetazolamide inhibits carbonic anhydrase, disrupting acid-base balance and contributing to limb defects.

Question 27

What congenital malformation is associated with acetazolamide exposure in utero? A. Spina bifida B. Anencephaly C. Ectrodactyly (lobster claw hand) D. Microcephaly

Answer 27

C. Ectrodactyly (lobster claw hand) Explanation: Acetazolamide causes forelimb ectrodactyly, likely due to CO₂ elevation.

Question 28

Which chemical is known to induce maternal anemia and skeletal defects in rabbit fetuses? A. Hydroxyurea B. Diflunisal C. Cadmium D. Vinclozolin

Answer 28

B. Diflunisal Explanation: Diflunisal causes severe maternal anemia, leading to fetal skeletal malformations via hypoxia.

Question 29

What is the primary cause of embryopathies observed with hydroxyurea exposure? A. Hormonal imbalance B. Enzyme inhibition C. Reduced uterine blood flow D. Increased zinc levels

Answer 29

C. Reduced uterine blood flow Explanation: Hydroxyurea decreases uterine blood flow, causing craniofacial and pericardial hemorrhages in embryos.

Question 30

Which protein binds metals and contributes to fetal zinc deficiency when induced? A. Albumin B. Metallothionein C. Ferritin D. Ceruloplasmin

Answer 30

B. Metallothionein Explanation: Metallothionein binds zinc and other metals; when induced in the mother, it deprives the fetus of zinc.

Question 31

Which heavy metal is directly toxic to the placenta and can cause fetal death? A. Mercury B. Lead C. Cadmium D. Arsenic

Answer 31

C. Cadmium Explanation: Cadmium accumulates in the placenta and is known to cause fetal lethality.

Question 32

Which enzyme detoxifies glucocorticoids in the placenta? A. CYP3A4 B. Aromatase C. 11β-HSD2 D. DIO2

Answer 32

C. 11β-HSD2 Explanation: 11β-HSD2 converts active glucocorticoids to their inactive forms, protecting the fetus from stress hormone exposure.

Question 33

Hyperthermia during the first trimester is associated with which defects? A. Neural tube defects, oral clefts, heart defects B. Kidney malformations and limb fusion C. Lung hypoplasia and anophthalmia D. Microcephaly and craniosynostosis

Answer 33

A. Neural tube defects, oral clefts, heart defects Explanation: Elevated maternal temperature during early pregnancy can disrupt neural and cardiac development.

Question 34

Barker's hypothesis links early developmental conditions to: A. Adult behavior only B. Cancer resistance C. Long-term health and disease risk D. Genetic mutation rates

Answer 34

C. Long-term health and disease risk Explanation: Barker’s hypothesis suggests that early-life exposures influence the risk of diseases like hypertension and diabetes later in life.

Question 35

What does ICH stand for in the context of pharmaceutical regulation? A. International Council for Hazardous Chemicals B. International Commission on Health C. International Conference of Harmonization D. Integrated Chemical Hazard Board

Answer 35

C. International Conference of Harmonization Explanation: ICH stands for International Conference of Harmonization of Technical Requirements for Pharmaceuticals for Human Use.

Question 36

Which study segment focuses on teratogenicity and fetal structural defects? A. Segment I B. Segment II C. Segment III D. Multigeneration test

Answer 36

B. Segment II Explanation: Segment II tests evaluate teratogenic effects and fetal anatomy following exposure during organogenesis.

Question 37

Which study design involves breeding F1 generation to produce F2 for evaluating generational effects? A. One-generation test B. Segment I study C. Multigeneration test D. Reproductive assay

Answer 37

C. Multigeneration test Explanation: Multigeneration tests involve breeding F1 to generate F2 to assess potential long-term or heritable toxicity.

Question 38

Which two rodent species have the highest data concordance with humans in toxicology? A. Rats and guinea pigs B. Rabbits and hamsters C. Rats and mice D. Mice and dogs

Answer 38

C. Rats and mice Explanation: Rats and mice show approximately 90% concordance with human developmental toxicology outcomes.

Question 39

Which U.S. act added a 10-fold safety factor to protect children from pesticide exposure? A. Clean Air Act B. Safe Drinking Water Act C. Food Quality Protection Act D. Children’s Health Equity Act

Answer 39

C. Food Quality Protection Act Explanation: The FQPA of 1996 introduced an additional safety margin for children due to differences in exposure and physiology.

Question 40

Which assay involves dosing pregnant mice and observing offspring for external malformations? A. Whole Embryo Culture B. Chernoff-Kavlock Assay C. BBDR Model D. Primordial Follicle Test

Answer 40

B. Chernoff-Kavlock Assay Explanation: The Chernoff-Kavlock assay is an in vivo screening test to detect developmental toxicity during organogenesis.

Question 41

Which animal model is known for transparency and high-throughput embryonic development studies? A. Rabbit B. Mouse C. Guinea pig D. Zebrafish

Answer 41

D. Zebrafish Explanation: Zebrafish embryos are transparent and rapidly develop, making them suitable for high-throughput toxicity testing.

Question 42

What does BMD stand for in dose-response assessment? A. Biological Molecular Dose B. Base Model Derivation C. Benchmark Dose D. Balanced Median Dose

Answer 42

C. Benchmark Dose Explanation: Benchmark Dose uses all available data to define a point of departure on the dose-response curve.

Question 43

Which model uses target organ concentration to improve dose-response predictions? A. PBPK Model B. NOAEL Model C. EPA Default Model D. Organ System Index

Answer 43

A. PBPK Model Explanation: Physiologically Based Pharmacokinetic (PBPK) models simulate tissue concentrations to enhance cross-species extrapolation.

Question 44

What is the first step in an Adverse Outcome Pathway (AOP)? A. Clinical symptom observation B. Genetic mutation C. Molecular initiating event D. Histopathology finding

Answer 44

C. Molecular initiating event Explanation: AOPs begin with a chemical interacting at the molecular level, triggering a cascade of biological events leading to toxicity.

Question 45

Which signaling molecule is central to limb and brain patterning and affected in teratogenesis? A. FGF B. SHH C. BMP D. EGF

Answer 45

B. SHH Explanation: Sonic Hedgehog (SHH) is crucial for embryonic patterning and disruption leads to severe malformations.

Question 46

Which protein inhibits BMP signaling and is named from slang for 'head'? A. TGFβ B. SHH C. Noggin D. EGF

Answer 46

C. Noggin Explanation: Noggin is a regulatory protein that suppresses BMP activity and influences neural development.