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Chapter 23. Toxic Effects of Metals

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Which of the following is NOT a major excretory pathway of metals?

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a. sweat.

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b. urine.

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c. respiration.

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d. feces.

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e. hair.

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Metallothioneins:

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a. are responsible for metal transport in the bloodstream.

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b. are involved in the biotransformation of metals.

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c. invoke hypersensitivity reactions.

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d. provide high-affinity binding of copper and mercury.

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e. are involved in extracellular transport of metals.

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Which of the following metal-binding proteins is NOT correctly paired with the metal it binds?

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a. transferrin—iron.

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b. ceruloplasmin—copper.

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c. metallothioneins—zinc.

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d. ferritin—lead.

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e. albumin—nonspecific metal binding.

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Which of the following groups is LEAST likely to chelate metals?

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a. —COOH.

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b. —Cl.

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c. —NH.

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d. —OH.

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e. —SH.

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What is the mechanism of toxicity of arsenic (As)?

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a. inhibition of mitochondrial respiration.

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b. impairment of calcium uptake by membrane transporters.

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c. accumulation in renal corpuscle.

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d. abolition of sodium–potassium gradient.

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e. destruction of surfactant in the lungs.

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Lead’s toxicity is largely due to its ability to mimic and interfere with normal functioning of which of the following ions?

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a. Na+.

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b. K+.

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c. Cl.

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d. Fe2+.

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e. Ca2+.

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Which of the following statements regarding mercury (Hg) toxicity is FALSE?

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a. A major source of environmental mercury is rainwater.

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b. Mercury vapor is much more dangerous than liquid mercury.

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c. Mercury vapor inhalation is characterized by fatigue and bradycardia.

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d. Microorganisms in bodies of water can convert mercury vapor to methylmercury.

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