General principles

Question 1

Place the following mechanisms of toxin delivery in order from most effective to least effective—1: intravenous; 2: subcutaneous; 3: oral; 4: inhalation; 5: dermal.

Answer 1

4,1,2,3,5

Question 2

Toxic chemicals are most likely to be biotransformed in which of organ?

Answer 2

Liver

Question 3

When chemicals A and B are administered simultaneously, their combined effects are far greater than the sum of their effects when given alone. The chemical interaction between chemicals A and B can be described as which of the following?

Answer 3

Synergistic

Question 4

With respect to dose–response relationships, which of the following is true?

Answer 4

Quantal dose–response relationships allow for the analysis of a population’s response to varying dosage.

Question 5

When considering the dose–response relationship for an essential substance:

Answer 5

adverse responses increase in severity with increasing or decreasing dosages outside of the homeostatic range.

Question 6

The therapeutic index of a drug:

Answer 6

describes the ratio of the toxic dose to the therapeutic dose of a drug.

Question 7

The severity of a toxicant depends, in large part, on the concentration of the toxicant at its site of action. Which of the following will decrease the amount of toxicant reaching its site of action?

Answer 7

excretion via the kidneys

Question 8

All of the following are common effects of toxicants on target molecules

Answer 8

• Blockage of neurotransmitter receptors.
• interference with DNA replication due to adduct formation.
• cross-linking of endogenous molecules.
• mounting of an immune response.

Question 9

Which of the following would have the largest negative impact on intracellular ATP levels?

Answer 9

interference with electron delivery to the electron transport chain.

Question 10

What happens when a toxicant induces elevation of cytoplasmic calcium levels?

Answer 10

Mitochondrial uptake of calcium dissipates (remove/move) the electrochemical gradient needed to synthesize ATP.

Question 11

Cytochrome c is an important molecule in initiating apoptosis in cells. All of the following regarding cytochrome c are true

Answer 11

• The release of cytochrome c into the cytoplasm is an important step in apoptosis initiation.
• The loss of cytochrome c from the electron transport chain blocks ATP synthesis by oxidative phosphorylation.
• Loss of cytochrome c from the inner mitochondrial membrane results in increased formation of reactive oxygen species.
• Bax proteins mediate cytochrome c release.

Question 12

All of the following regarding DNA repair are true

Answer 12

• In a lesion that does not cause a major distortion of the double helix, the incorrect base is cleaved and the correct base is inserted in its place.
• Base excision repair and nucleotide excision repair are both dependent on a DNA polymerase and a DNA ligase.
• Pyrimidine dimers can be cleaved and repaired directly by DNA photolyase.
• Recombinational repair requires that a sister strand serves as a template to fill in missing nucleotides

Question 13

Apoptosis can serve as a tissue repair process in a number of cell types. In which of the following cell types would this be a plausible mechanism of tissue repair?

Answer 13

gastrointestinal epithelium.

Question 14

Important in hazard identification

Answer 14

• Structure–activity analysis.
• in vitro tests.
• animal bioassays.
• Epidemiology

Question 15

The probability of an adverse outcome is defined as:

Answer 15

RISK

Question 16

The systematic scientific characterization of adverse health effects resulting from human exposure to hazardous agents is the definition of:

Answer 16

risk assessment

Question 17

Which of the following represents the dose below which no additional increase in response is observed?

Answer 17

Threshold