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Toxicology

 

Multiple choice questions may have more than one correct answer.  Indicate all that apply. 

 

 

11 pts
  • Which of the following is true?
  1. When the neuron is in the resting state there is no potential across the membrane.
  2. The concentration of Na+ is higher inside the nerve cell than outside the cell in the resting state.
  3. Na+ and K+ ions move into and out of the nerve cell by diffusion across the membrane.
  4. Negatively charged proteins move from outside the nerve cell to the inside to help establish a negative potential gradient in the resting neuron.
  5. Curare results in overstimulation of the sympathetic nervous system.
  6. Scopolamine produces tachycardia.
  7. Saltatory conduction increases the rate at which nerve impulses are transmitted.
  8. Every neurotransmitter released into the synaptic gap must find its way to a receptor site on the neighboring neuron for proper nerve transmission.
  9. Malathion must be bioactivated before it is an effective neurotoxin.
  10. Dermal exposure to organophosphate pesticides is a significant exposure route.
  11. Atropine would be an effective antidote to poisoning by DDT.

 

5 pts
  • Neurotoxins work by which of the following mechanisms?
  1. Blocking release of neurotransmitters
  2. Blocking receptor site for neurotransmitters
  3. Blocking action of enzymes responsible for destruction of excess neurotransmitters
  4. Demyelinating axon sheath
  5. Changing ion movement across nerve membrane

 

3 pts
  • Why would an infant be more likely to be susceptible to poisoning by PbCl2 than an adult?
10 pts

 

  1. Which of the following is classified as a known human carcinogen (highest category) by at least one agency: EPA, IARC, or NTP? (Indicate which agency in your answer)
  2. Toluene
  3. asbestos
  4. Hg
  5. Formaldehyde
  6. Methyl methacrylate
  7. Styrene
  8. Perchloroethylene
  9. Mustard gas
  10. Ba
  11. AsH3

 

 

4 pts
  • Which of the following would indicate neoplasia in animal studies?
  1. an increase in the frequency of a tumor that also occurs in a control
  2. development of tumors not found in controls
  3. occurrence of tumors earlier than in controls
  4. a positive Ames test
3 pts

 

 

  1. Explain why succinyl choline is used in surgery and how it works.
7 pts

 

 

  1. Match the following mechanisms of toxicity with the neurotoxin.
  2. Botulinium i) blocks receptor sites of acetylcholinesterase
  3. Tetradotoxin ii) blocks release of acetylcholine
  4. Atropine iii) blocks sodium channels
  5. Hexachlorobenzene iv) damages myelin sheath
  6. Black widow spider venom v) increases permeability of membrane to sodium
  7. DDT vi) massive release of acetylcholine
  8. n-hexane vii) none of the above mechanisms

 

3 pts
  • How can an organophosphorus pesticide be very toxic to an insect but not nearly as toxic to a mammal?

 

10 pts
  • We did not talk specifically about them in our modules, but find an appropriate reference and cite it for your answers for the following:
  1. Explain the relationship between pyrethrins and pyrethroids.
  2. Why is a synergistic agent added to most formulations?

 

Which of the following statements about pyrethrins and pyrethroids is true?

  1. These materials are acetylcholinesterase inhibitors.
  2. Pyrethrins have a lower LD50 for mammals than parathion.
  3. Pyrethrins appear to affect the ion channels involved in nerve conduction.
  4. Pyrethrins are derived from natural plant sources.
  5. Neither pyrethrins nor pyrethroids are considered to be persistent pesticides.
  6. Both of these materials are more toxic to fish and aquatic species than to mammals.

 

5 pts
  • Which of the following statements is true.
  1. There is no U.S. drinking water standard for atrazine.
  2. Atrazine would be considered a persistent herbicide.
  3. EPA considers atrazine a chemical that is likely to cause cancer in humans.
  4. Atrazine has been banned in the European Union but continues to be legal in the United States.
  5. Atrazine is considered a persistent organic pollutant under the Stockholm Convention on POPs.
7 pts

 

 

  1. What does the term “ionizing radiation” mean? Are alpha, beta, and gamma radiation all ionizing radiation?  Describe the differences in how you would go about protecting yourself against these three different types of radiation.
3 pts

 

 

  1. During the height of the Fukushima disaster, radiation levels were reported as high as 400 mSv per hour. How long could an emergency response worker have been exposed to that level of radiation before he accumulated a lethal dose?

 

5 pts
  • Which of the following does not occur in the tubules?
  1. Filtration of proteins from blood plasma into glomerular fluid
  2. Reabsorption of water from glomerular fluid back into blood
  3. Reabsorption of glucose from glomerular fluid back into blood
  4. Reabsorption of inulin from glomerular fluid back into blood
  5. Secretion of p-aminohippuric acid from blood into glomerular fluid
6 pts

 

 

  1. Distinguish between a genotoxic agent and an epigenetic agent. Give an example of each.

 

4 pts
  • Which of the following statements is true?
  1. A substance is classified as a human carcinogen after it is shown to produce cancer in one animal species.
  2. Most currently known carcinogens are classified as procarcinogenic.
  3. Additions or deletions of base pairs is likely to result in a more toxic effect than substitution of one base for another.
  4. Development of a neoplasm is sufficient for a diagnosis of cancer.
4 pts

 

 

  1. Explain how an epoxide could be a genotoxic agent.

 

3 pts
  • List three differences between malignant and benign tumors.
3 pts

 

 

  1. Distinguish between a carcinoma, sarcoma, and lymphoma.

 

4 pts
  • What amino acids would be coded for from the following DNA sequence (starting from the left)?
  1. CTAGGTACTA
  2. What would be the effect of replacing the first T with an A?
  3. What would be the effect of deleting the first T?
  4. Would nitrous acid cause a frame shift or base pair change mutation?
3 pts

 

 

  1. Give an example of a chemical that the state of California considers to be a carcinogen, but no other agency does.
5 pts

 

 

  1. Which of the following would you be likely to find in soil samples years after its application to farmland?
  2. Malathion
  3. Dieldrin
  4. Dichlorvos
  5. Toxaphene
  6. Lindane
4 pts

 

 

  1. How and why does treatment for poisoning by Malathion differ from poisoning by Sevin?

 

4 pts
  • Which of the following would be true of a “persistent” pesticide?
  1. Low vapor pressure
  2. High water solubility
  3. Low Kow
  4. Low biodegradation rate
4 pts

 

 

  1. Which of the following statements is true?
  2. Rachel Carson’s Silent Spring was referring to the effect of pesticides on humans in its title.
  3. Pralidoxime is administered to counteract the effects of exposure to diazinon.
  4. The size of pores in the capillaries at the glomerulus is smaller than those of other types of capillary membranes.
  5. Cholestasis is associated with a disruption of bile flow.
3 pts

 

 

  1. The liver gets much of its blood supply from the portal vein. Why is this an important fact with respect to how the effects of a toxin may depend upon the route of exposure?

 

5 pts
  • Describe in your own words the problems created by using molecular oxygen as a recipient of the electrons from the oxidation of carbon compounds.

 

4 pts
  • Which of the following symptoms would be associated with exposure to a neurotoxin that blocks a muscarinic receptor site?
  1. Increased salivation
  2. Bradycardia
  3. Hypertension
  4. Hyperglycemia

 

10 pts
  • Toxaphene is one of 12 Persistent Organic Pollutants (POPs; also called the Dirty Dozen) identified by the Stockholm Convention on Persistent Organic Pollutants (2001). Characteristics of POPs are:
  • Toxicity
  • Environmentally persistent
  • Water insolubility
  • Semi-volatile and capable of traveling great differences through atmospheric cycling

Write a “brief” (1/2 – 1 page) description that

  1. Defines what toxaphene is
  2. Describes the physical and chemical characteristics that allows toxaphene to meet the definitions of a POP
  3. Discusses how one can be exposed to toxaphene and what the major toxic effects are.

 

4 pts
  • Match the primary target organ or effect with the toxicant. Some chemicals may fit more than one category, but use the organs or effect in the right hand column only once.
    1. Anabolic steroids                         i)   cirrhosis
    2. Ethanol                                     ii)  liver cancer
    3. Carbon tetrachloride             iii) steatosis
    4. Vinyl chloride                         iv) choloestasis

 

2 pts
  • A cholinesterase test would be useful for workers exposed to:
  1. Mercury
  2. Lead
  3. Trichloroethylene
  4. Parathion

 

3 pts
  • A decrease or stoppage of bile flow with resulting retention of bile salts and bilirubin is called:
  1. Fatty liver
  2. Lipid peroxidation
  3. Cholestasis
  4. Cirrhosis

 

3 pts
  • Which of the following is true of the Blood-Brain Barrier?
  1. Excludes highly polar compounds
  2. Contains a large number of transport proteins
  3. Is present in both the CNS and PNS

 

6 pts
  • Which of the following are true?
  1. A fatty liver could result from inhibition of the synthesis of lipoproteins.
  2. The liver normally excretes fats into the blood as a triglyceride.
  3. Chloestasis is associated with damage to the proximal tubule.
  4. Chlorinated solvents, such as CCl4, have been associated with peroxidation of lipid membranes.
  5. Canaliculi carry blood between hepatocytes.
  6. Hg2+ is associated with damage to the proximal tubule.

 

5 pts
  • If the concentration of inulin in the urine is 24 mg/ml, the concentration in the blood plasma is 0.29 mg/ml, and the urine production is 1.3 ml/min what is the glomerular filtration rate? Would you expect the BUN value to be greater or less than 25 mg/100 ml?
4 pts

 

 

  1. Match the following:
  2. Chloracne    sodium hydroxide
  3. Uticaria   PAHs
  4. Photosensitivity PCBs
  5. Immediate tissue necrosis DMSO

 

9 pts
  • Which of the following statements is true?
  1. The size of pores in the capillaries at the glomerulus is larger than pores found in other membranes.
  2. Proteins found in the blood are normally filtered out at the glomerulus and then reabsorbed in the Loop of Henle.
  3. Release of aldosterone increases the ionic strength of the urine.
  4. Vasopressin tends to decrease urine output.
  5. Exposure to chromium is associated with glycosuria.
  6. Halogenated solvents are associated with damage to proximal tubules in the kidney.
  7. About 10% of the blood volume that passes through the glomerulus passes out of the capillaries and is collected in the Bowman’s capsule.
  8. About 1% of the glomerular fluid is not reabsorbed in the tubules and is excreted as urine.
  9. Inulin clearance is a measure of the efficiency of the efficiency of glomerular filtration.
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