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Chapter 10. Developmental Toxicology

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Diethylstilbestrol (DES):

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a. was used to treat morning sickness from the 1940s to the 1970s.

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b. was found to affect only female offspring in exposed pregnancies.

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c. greatly affects the development of the fetal brain.

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d. exposure increases the risk of clear cell adenocarcinoma of the vagina.

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e. is now used to treat leprosy patients.

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Early (prenatal) exposure to which of the following teratogens is most often characterized by craniofacial dysmorphism?

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a. thalidomide.

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b. retinol.

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c. ethanol.

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d. tobacco smoke.

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e. diethylstilbestrol (DES).

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The nervous system is derived from which of the following germ layers?

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a. ectoderm.

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b. mesoderm.

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c. epidermal placodes.

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d. paraxial mesoderm.

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e. endoderm.

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Toxin exposure during which of the following periods is likely to have the LEAST toxic effect on the developing fetus?

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a. gastrulation.

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b. organogenesis.

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c. preimplantation.

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d. third trimester.

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e. first trimester.

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Regarding prenatal teratogen exposure, which of the following statements is FALSE?

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a. Major effects include growth retardation and malformations.

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b. Exposure to teratogens during critical developmental periods will have more severe effects on the fetus.

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c. There is considered to be a toxin level threshold below which the fetus is capable of repairing itself.

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d. The immune system of the fetus is primitive, so the fetus has little to no ability to fight off chemicals and repair itself.

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e. Embryo lethality becomes more likely as the toxic dose is increased.

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Which of the following stages of the cell cycle are important in monitoring DNA damage and inhibiting progression of the cell cycle?

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a. G1–S, anaphase, M–G1.

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b. G1–S, S, G2–M.

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c. S, prophase, G1.

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d. G2–M, prophase.

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