Chapter 4 Questions
Chapter 4 Questions_091609.doc
4.1.1
1.
Toxicity refers to the capability of a substance to
a)
b)
c)
d)
2.
almost no chemicals have a toxic effect on humans.
many toxicants can accumulate in the body.
humans can ingest small amount of toxic substances with little or no effect.
acute exposures to toxicants are usually less harmful than chronic exposures.
When molecules are metabolized they
a)
b)
c)
d)
8.
Single, relatively high dose
Single, relatively low dose
Long-term exposures of relatively high doses
Long-term exposures of relative low doses
The process of metabolism explains why
a)
b)
c)
d)
7.
Single, relatively high dose
Single, relatively low dose
Long-term exposures of relatively high doses
Long-term exposures of relatively low doses
Chronic toxicants are characterized by what features?
a)
b)
c)
d)
6.
permanent damage is done to an organism
a person starts to feel pain or discomfort
toxic effects begin to occur
the level at which some antidote can have an effect
Acute toxicants are characterized by what features?
a)
b)
c)
d)
5.
is a single, pure chemical instead of mixture.
is a naturally occurring toxic compound.
is made synthetically in a laboratory.
is low molecular weight molecule.
With regard to toxic dose, the threshold is the level at which
a)
b)
c)
d)
4.
cause systemic harm to a living organism.
damage an organ in a living organism.
adversely modify a biochemical system.
All of the above.
A toxin is a toxicant that
a)
b)
c)
d)
3.
Introduction to Toxicology I
usually become a less toxic molecules.
usually becomes a more toxic molecules.
can become either more toxic or less toxic.
always become less toxic.
An LD50 represents the
a)
b)
c)
d)
9.
amount of a substance that kills 50% of a test population
the concentration of a substance that kills 50% of a test population
amount of a substance that is known to have killed at least 50 people due to accidental exposure.
the concentration of a substance that is known to have killed at least 50 people due to accidental exposure.
The methodology used to determine an LD50 involves
a)
b)
c)
d)
slowly increasing the dose until 50% of a test population dies.
slowly increasing the dose until 5% of a test population dies and them multiplying the dose by ten.
dosing animals to get a wide range of death rates and interpolating the data to 50%.
finding the minimum does that kills 100% of a population and then dividing by two.
10. What dimension is not used to represent and LC50?
a)
b)
c)
d)
ppm
mg/M3
mg/mL
g/L
11. Poisons are compounds with an LD50
a)
b)
c)
d)
≤ 50 mg
≤ 50 mg/kg
≥ 50 mg
≥ 50 mg/kg
12. What percentage of compounds can be classified as poisons?
a)
b)
c)
d)
A small percent.
about 25%
about 50%
almost 80%
13. The toxicity values shown in Table 4.1.1.2 cover a range of how many orders of magnitude?
a)
b)
c)
d)
3
5
8
11
14. Which statement is true?
a)
b)
c)
d)
In general, synthetic compounds are more toxic than naturally-occurring compounds.
In general, naturally-occurring compounds are more toxic than synthetic compounds.
There is no relationship between the source of a compound and its toxicity.
More complex molecules tend to be more toxic.
15. Table 4.1.1.3 shows data that allows one to conclude that
I.
II.
III.
IV.
a)
the toxic dose is largely independent of route of exposure
most compounds have remarkably similar toxic doses
LC50 data is often reported with different time exposures
oral LD50 doses are generally lower than dermal (skin) LD50 doses
I and III
b) II and III
c) I and II
d) III and IV
16. Table 4.1.1.4 shows that
I.
II.
III.
IV.
a)
b)
c)
d)
most species of animal react about the same to a particular dose (per kg) of a toxicant.
LD50 values vary widely according to species.
generally, the larger the animal, the lower the LD50.
generally, the larger the animal, the higher the LD50.
I and III
II and III
II and IV
only II
17. To extrapolate animal testing to humans, it has been found that
a) using monkeys provides very similar toxicity results as those shown for humans
b) there is no animal species that simulates human responses well, but, generally, testing several species lead
to reasonably good estimate of human toxicity.
c) in general other animals are mostly more sensitive to toxicants than are humans.
d) in general other animals are mostly less sensitive to toxicants than are humans.
18. Figure 4.1.1.3 shows that the toxic effect of a substance on an individual depends
a)
b)
c)
d)
on about ten factors
almost entirely on factors that are beyond the control of the individual
upon factors that are remarkably consistent in a population of individuals.
mostly on two main factors.
19. Figure 4.1.1.1 shows that
a)
b)
c)
d)
the dose-response curve is linear enough to generally assume that an LD 50 is ten times smaller than an LD5.
most compounds have a threshold nearly equally to zero.
the dose-response curve is not linear over a wide range of doses.
generally, higher does ironically lead to smaller responses.
20. Synergistic effects explain why
the effect of being exposed to two toxicants is sometime less than the predicted “sum” of the
exposures.
II. the effect of being exposed to two toxicants is sometime more than the predicted “sum” of the
exposures.
III. there can be variation in the response of a group of people to that same dose of a toxicant.
IV. many people have a delayed reaction to a toxicant.
I.
a)
b)
c)
d)
I and III
II and III
II and IV
IV
21. Antagonistic effects explain why
I.
the effect of being exposed to two toxicants is sometime less than the predicted “sum” of the
exposures.
II. the effect of being exposed to two toxicants is sometime more than the predicted “sum” of the
exposures.
III. there can be variation in the response of a group of people to that same dose of a toxicant.
IV. many people have a delayed reaction to a toxicant.
a)
b)
c)
d)
I and III
II and III
II and IV
IV
22. Which is true?
a) Synthetic compounds are more toxic than naturally-occurring compounds.
b) Synthetic compounds are less toxic than naturally-occurring compounds.
c) We can draw no general conclusion about the toxicity of a compound based on whether is it synthetic or
naturally –occurring.
d) If a naturally-occurring compound is also prepared synthetically, it will not have the same toxicity
behavior.
4.1.2
1.
Acute toxicants are characterized by what features?
a)
b)
c)
d)
2.
a high dose is required.
after sensitization has occurred, the reaction is immediate.
they involve the immune system.
All of the above.
“Simple asphyxiants”
a)
b)
c)
d)
5.
allergens
poisons
asphyxiants
irritants
There is often a delay between initial exposure and the response for allergens, but they are considered to be
acute toxicants because
a)
b)
c)
d)
4.
Single, relatively high dose
Single, relatively low dose
Long-term exposures of relatively high doses
Long-term exposures of relatively low doses
The most common toxic effect of chemicals is the category of
a)
b)
c)
d)
3.
Acute Toxicity
are chemically unreactive.
displace oxygen from the air.
can be lighter or heavier than the average molar mass of air.
All of the above.
“Chemical asphyxiants”
a)
interfere with oxygen uptake through a chemical reaction in the body.
b) are actually the same as “simple asphyxiants.”
c) are usually not gases.
d) cause the blood to coagulate.
6.
Pulmonary edema
a)
b)
c)
d)
7.
Teratogens and fetotoxicants
a)
b)
c)
d)
8.
have immediate and obvious effects when ingested.
interfere with the genetic process .
can have an effect on a fetus, even though the mother may not know this.
are frequently encountered in introductory chemistry labs.
Substances that affect the central nervous system are called
a)
b)
c)
d)
9.
is the condition of excess fluid in the lungs.
can be caused by non-asphyxiant chemicals that react with lung air sacs.
can occur rapidly or slowly.
All of the above.
hepatotoxicants
neurotoxins
nephrotoxicants
teratogens
What compounds often used as pesticides are also neurotoxins?
a)
b)
c)
d)
cholinesterases
nephrotoxicants
organophosphates
tetratogens
4.1.2
Questions/Problems.
Using the Ideal Gas Law and Dalton’s Law of Partial Pressures:
Assume that you are in a room that measures 15x15x8 feet containing normal air with 21% O 2. a) If a fire
extinguisher with five pounds of solid CO2 in it is completely discharged, what will the level of % CO2 in the
atmosphere? What will be the (reduced) level of O2? Does discharging this extinguisher (to put out a fire)
jeopardize the safety of the occupants of the room in terms of decreased O2 concentration? b) Assume that you are
using a Dewar flask of liquid nitrogen in order to cool some experimental apparatus. What happens to the O2
concentration in the room, over time as the N2 evaporates, if about three liters of liquid nitrogen is evaporated?
All of your previous questions have had answers to choose from. Will this? How will the student answer the
questions?
4.2.1
1.
Chronic Toxicants
The likelihood of suffering an adverse, chronic effect while working with chemicals in undergraduate
laboratories is
a) small, because almost no chronic substances are allowed in labs.
b) small, because chronic exposure in academic labs is unlikely.
c) moderate, because academic labs take few precautions against exposure to chronic toxins.
d) large, but we don’t know how large since all of the effects are delayed.
2.
Which statement is true?
a)
b)
c)
d)
3.
Chronic toxicity studies
a)
b)
c)
d)
4.
Acute toxicity does not predict chronic toxicity.
We know much more about acute toxicity that we do about chronic toxicity.
Studies that evaluate chronic toxicity are very expensive.
All of the above are true.
are sometimes not conducted because we don’t know what symptom or effect to measure.
sometimes occur based on the accidental exposure of a group of people to a chemical.
are usually more definitive in establishing a cause –effect relationship than acute toxicity studies.
A and B are true.
It is known that we ingest small amounts of large numbers of synthetic and naturally-occurring chronically toxic
compounds regularly
a) and this accounts for the relatively high cancer rate in the United States.
b) but since the toxic effects of these substances are not detected it is clear that the body’s defense system can
usually handle these chemical assaults.
c) but the delay time between ingestion and illness is predicted to be over 80 years so the effects are rarely
seen.
d) but the effect of these compounds is masked by other illnesses.
5.
Which factors are the primary causes of chronic disease?
I.
II.
III.
IV.
a)
b)
c)
d)
6.
Genetics.
Lifestyle choices.
Age.
Chemicals.
I, II and IV.
II, III, and IV.
I, II and III.
I and IV.
The element, mercury,
a) is much more toxic by ingestion than inhalation.
b) produces symptoms as soon as blood level concentrations rise to detectable levels.
c) was widely used in laboratories in the 20th century where spills of the liquid Hg occurred and exposed
chemists to Hg vapors.
d) is the preferred liquid in thermometers because it is so chemically inert.
7.
The Laboratory Standard (OSHA 29 CFR 1910.1450)
a)
b)
c)
d)
ignores the issue of chronic toxicity because it is so rare in chemistry labs.
regulates the specific levels of known chronic toxicants.
requires that scientists be aware of risks and hazards associated with chronic toxicants.
requires that the ACGIH determines the TLVs for all chronic toxicants.
4.3.1 Carcinogens
1.
What is the estimated percent of cancers in the U.S. are attributable to chemical exposure in the workplace?
a)
b)
c)
d)
2.
What percentage of chemicals that is known to cause cancer in humans is regulated by OSHA?
a)
b)
c)
d)
3.
less than 10%
about 25%
about 60%
100%
What element and its compounds are regulated by OSHA?
a)
b)
c)
d)
4.
< 5%
about 10%
about 18%
about 26%
asbsestos
arsenic
cadmium
mercury
For most chemists who work in labs,
a)
it is probable that they will use and handle some carcinogens, but the likelihood of contracting cancer based
on lab activity is very small if appropriate steps are taken to limit exposure.
b) it is very unlikely that they will use and handle any carcinogens since carcinogens are so highly regulated.
c) it is very likely that they will use and handle carcinogens and some may develop cancer but establishing the
causal link to chemical exposure is almost impossible.
d) they will avoid using anything carcinogenic since OSHA regulations make it illegal to require a chemist to
use carcinogens without signing a release statement.
5.
What percentage of chemicals tested for carcinogenicity actually turn out to be carcinogens?
a)
b)
c)
d)
6.
less than 5%
about 10%
about 45%
about 60%
The percentage of chemicals found to be carcinogens in lab tests is probably higher than the actual percentage
of human carcinogens in all known chemicals because
a) these expensive tests are more likely to be run on compounds that are already suspected to be carcinogens.
b) very high doses are used and the high-dose-to-low-dose extrapolation probably overestimates the actual
chance of the chemical being a carcinogen in humans,
c) humans have a better DNA repair mechanism that some animals.
d) All of the above.
7.
Which statement is true?
a)
b)
c)
d)
Most carcinogens are mutagens.
All mutagens are harmful.
About 50-60% of known mutagens are carcinogens.
Mutagenicity tests are only performed on known carcinogens.
8.
Which statement is true?
a) OSHA regulates about 30 substances as known carcinogens.
b) OSHA regulates almost 300 substances as known carcinogens.
c) OSHA recommends, but does not require, that special practices be established when handling select
carcinogens.
d) OSHA has regulates mutagens more strictly than carcinogens.
9.
A substance is a “select carcinogen” if it
a) is regulated by OSHA as a carcinogen.
b) is “known to be a carcinogen” in the Annual Report on Carcinogens published by the NTP
c) is listed as Group 1, Group 2A or Group 2B by the IARC and causes statistically significant tumor
incidence under specified conditions.
d) All of the above.
4.3.2
1.
A xenobiotic substance is one which
a)
b)
c)
d)
2.
Hydrolysis.
Reduction.
Oxidation.
All of the above.
In Phase 1 Biotransformation, epoxide function groups become
a)
b)
c)
d)
5.
naturally-occurring, less toxic substance.
more hydrophilic form that can be more easily eliminated.
more hydrophobic form that can be more easily eliminated.
more hydrophobic form that is less toxic.
In Phase 1 Biotransformation, enzymes are used to effect which chemical reaction?
a)
b)
c)
d)
4.
has an unusually high toxicity.
is usually eliminated before it can metabolize.
does not normally occur in the body.
was synthesized by Zena the Warrior Princess
The purpose of biotransformation of a xenobiotic substance in the body is to change it into a
a)
b)
c)
d)
3.
Biotransformation, Bioaccumulation, and Elimination of Toxicants
alcohols.
carboxylic acids.
phenols.
ethers.
In Phase 1 Biotransformation, chemical toxicants
a)
b)
c)
d)
are always converted into less toxic substances.
are always converted into more toxic substance.
can be converted into substances that can be either more or less toxic.
None of the above.
6.
In Phase 2 Biotransformation, what class of molecules is used to effect conjugation?
a)
b)
c)
d)
7.
In Phase 2 Biotransformation, xenobiotic substances are converted to
a)
b)
c)
d)
8.
4.3.3
have a central core of DNA or RNA.
have a protective protein coating.
are not alive.
All of the above.
are alive.
are all easily dyed.
cannot be killed with antibiotics.
contain no DNA.
Which poses the largest risk of infection upon exposure?
a)
b)
c)
d)
4.
Biological Hazards and Biosafety
Bacteria
a)
b)
c)
d)
3.
on the order of hours.
on the order of days.
on the order of years.
All of the above.
Viruses
a)
b)
c)
d)
2.
absorbed faster than it is eliminated.
absorbed slower than it is eliminated.
converted to a more hydrophilic form.
converted to a more hydrophobic form.
The half-life for the elimination of bioaccumulated substances is
a)
b)
c)
d)
1.
more hydrophobic forms that more easily react with enzymes.
more hydrophilic forms.
smaller molecules that are more hydrophilic.
larger molecules that are more hydrophobic.
In order for bioaccumulation to occur, a chemical toxicant must be
a)
b)
c)
d)
9.
Amino acids.
Carboxylic acids.
Alcohols.
Enzymes.
Hepatitus viruses.
HIV
Hepatitus and HIV have the same risk.
This depends upon the individual.
When comparing infectious agents with chemical toxicants
for chemical toxicants, “the dose makes the poison” while for infection agents, the dose is largely irrelevant
since even a tiny exposure can multiply in the body.
b) for both substances, “the dose makes the poison.”
c) using PPE for infectious agents is much more important since exposure usually leads to fatality.
d) different kinds of PPE are used for infectious agents as compared to chemical toxicants.
a)
5.
Which practice is generally not needed when using infectious agents?
a)
b)
c)
d)
6.
Which two practices are more important to consider when handling infectious agents as compared to handling
chemical toxicants.
a)
b)
c)
d)
7.
Using gloves.
Avoiding mouth pipetting.
Using chemical splash goggles.
None of the above.
Washing hands and disposing of sharps.
Washing hands and disinfecting work areas.
Disposing of sharps and disinfecting work areas.
Disposing of sharps and using gloves.
How many Biosafety Levels are established by the CDC and NIH?
a)
b)
c)
d)
Two
Three
Four
Five