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Chapter 23. Toxic Effects of Metals

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

a. sweat.

b. urine.

c. respiration.

d. feces.

e. hair.

Metallothioneins:

a. are responsible for metal transport in the bloodstream.

b. are involved in the biotransformation of metals.

c. invoke hypersensitivity reactions.

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

e. are involved in extracellular transport of metals.

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

a. transferrin—iron.

b. ceruloplasmin—copper.

c. metallothioneins—zinc.

d. ferritin—lead.

e. albumin—nonspecific metal binding.

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

a. —COOH.

b. —Cl.

c. —NH.

d. —OH.

e. —SH.

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

a. inhibition of mitochondrial respiration.

b. impairment of calcium uptake by membrane transporters.

c. accumulation in renal corpuscle.

d. abolition of sodium–potassium gradient.

e. destruction of surfactant in the lungs.

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

a. Na+.

b. K+.

c. Cl.

d. Fe2+.

e. Ca2+.

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

a. A major source of environmental mercury is rainwater.

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

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

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

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