48) Which of the following statements about the role of liver enzymes is most correct?
A) Liver enzymes always change potential toxins to substances that can be easily excreted from the body.
B) Liver enzymes may change an inert compound to a more reactive and harmful molecule.
C) Liver enzymes can help the body to bring the four humors (blood, phlegm, black bile and yellow bile)
back into a healthy balance.
D) Liver enzymes always convert potential toxins to substances that contain free radicals.
49) The known cause of approximately 30% of all cancers is
A) sedentary lifestyle.
B) obesity.
C) occupational factors.
D) prescriptions.
50) The carcinogenic hydrocarbons produced during the incomplete burning of organic materials are
known as
A) aromatic hydrocarbons.
B) styrene.
C) polycyclic aromatic hydrocarbons.
D) cycloalkanes.
51) Which class of compounds is thought to be possibly anticarcinogenic?
A) prostaglandins
B) oxidizing agents
C) reducing agents
D) antioxidants
52) Which of the following will have anticarcinogenic activity?
A) aromatic amines, such as β-naphthylamine
B) oncogenes
C) vitamin C, vitamin E, and β-carotene
D) polycyclic aromatic hydrocarbons, such as 3,4-benzopyrene
53) Which of the following has been shown to be involved in roughly 60% of lung cancers?
A) aromatic amines
B) β-carotene
C) hydroxytoluene (BHT)
D) P53 gene mutations
54) The simplest and least expensive method for testing for possible carcinogenic activity is
A) the Ames test.
B) animal testing.
C) epidemiological studies.
D) human testing.
55) The Ames test is used to screen for
A) all potential poisons.
B) heavy metal poisons.
C) mutagens.
D) carcinogens.
56) The study of the behavior of a specific population and cancer incidence is an example of ________
testing for carcinogenic activity.
A) Ames
B) animal
C) epidemiological
D) human
57) Which of the following is NOT used to gather evidence about whether a compound causes cancer in
humans?
A) bacterial screening for mutagenesis (the Ames test)
B) animal tests
C) measurement of birth defects
D) epidemiological studies
58) Substances that cause birth defects are called
A) mutagens.
B) androgens.
C) progestins.
D) teratogens.
59) A well-known teratogen is
A) thalidomide.
B) coniine.
C) BAL.
D) arsenic.
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60) Which of the following is the most hazardous teratogen, in terms of the greatest number of babies
affected?
A) birth control pills
B) ethyl alcohol
C) acetaminophen
D) heroin
61) Which would be classified as a reactive waste?
A) hydrogen sulfide
B) lithium bromide
C) metal
D) copper metal
62) The best way to dispose of a flammable waste is
A) process through a wastewater treatment plant.
B) bury in a landfill.
C) burn in an incinerator.
D) store in a sealed barrel.
63) The best way to handle hazardous wastes is
A) to bury them.
B) to incinerate them.
C) to chemically modify them.
D) to avoid producing them.
64) What is the most effective way to dispose of organic wastes?
A) bury them in landfills
B) incinerate them
C) recycle them
D) store them in special containers
65) Which of the following types of waste would be least hazardous?
A) corrosive waste
B) flammable waste
C) waste material from living plants
D) reactive waste
66) Which of the following statements best describes the circumstances that lead to chemical tragedies?
A) Hazardous and poisonous chemicals should be banned or destroyed so that accidents do not occur.
B) Most tragedies occur because of misuse of hazardous or poisonous chemicals.
C) Hazardous and poisonous chemicals cannot be made safe.
D) The risks of using hazardous chemicals always outweigh the benefits.
67) Which of the following types of hazardous waste requires special containers because it will react with
normal container materials?
A) corrosive waste
B) flammable waste
C) reactive waste
D) toxic waste
68) The “gold standard” for testing chemical toxicity is laboratory rats and mice. Which of the following
is NOT a disadvantage of testing with rodents?
A) Rodent studies are expensive.
B) Rodents have metabolic or physiological differences so the results may not apply to humans.
C) Rodent studies have often involved unrealistically high exposures to the substances being tested.
D) Rodent studies are relatively fast to carry out.
69) Which of the following shows great promise as a vertebrate system that will allow automated and
rapid testing of compounds?
A) embryonic rat cells
B) Drosophila melanogaster cells
C) embryonic zebrafish
D) plant cells
22.2 True/False Questions
1) Herbicides and insecticides are the only poisons to be found in a garden.
2) Many common garden plants are poisonous.
3) Toxicology is the study of poisons that come from synthetic sources, but not from natural sources.
4) Strong acids and bases can catalyze the hydrolysis of proteins.
5) Enzymes are often deactivated by oxidizing agents such as ozone.
6) Cyanide acts by blocking the oxidation of glucose in the cell.
7) Cyanides increase the ability of hemoglobin to carry oxygen.
8) The average adult requires 45 to 50 mg of iron every day.
9) Sodium fluoroacetate, also known as Compound 1080, is highly selective and poisonous only to
snakes.
10) Heavy metals act by binding to the —SH groups on enzymes, which makes the enzymes inactive.
11) Phosphorus-based insecticides such as parathion are less toxic than warfare nerve agents such as
soman.
12) Organic phosphorus insecticides are nerve poisons that work by binding to acetylcholinesterase and
blocking the breakdown of acetylcholine.
13) The LD50 value is the amount of a substance that will kill 50% of test animals.
14) The LD50 value for a given compound and species is the same no matter how the substance is
administered.
15) Botulin toxin is the most poisonous substance known.
16) Liver enzymes alter poisons to make them less toxic.
17) The P-450 enzymes oxidize water-soluble substances into fat-soluble substances that can easily be
excreted.
18) Only synthetic chemicals have been found to be carcinogenic.
19) Most carcinogens occur naturally.
20) If a compound is a carcinogen in rats, it will also be a carcinogen for mice.
21) The Ames test assumes that most carcinogens will also be mutagens.
22) A teratogen is a cancer-causing substance.
23) Genetics are a leading cause of death from cancer.
24) Most hazardous chemicals are so dangerous that we should never use them.
25) The National Academy of Sciences recommends that new, inexpensive and rapid tests that can
analyze many compounds for chemical safety be developed.
22.3 Short Answer Questions
1) Toxicology is the study of ________.
2) Name the poison in rosary pea seeds.
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3) What type of damage do all corrosive poisons cause to living tissue?
4) People with Alzheimer‘s disease are deficient in ________.
5) The system of liver enzymes that helps to detoxify poisons is called ________.
22.4 Essay Questions
1) What is LD50? Use the following compounds and their LD50s to explain.