Biology of Toxins SAMPLE QUESTIONS for the 1st Midterm Exam - 2006

1. Which of the following is not generally a risk to users of the club drug, Ecstasy? a. Brain herniation b. Dangerously elevated body temperature c. Concentrated body fluids a. Cerebral edema 2. Which of the following is the best general description of the function of enzymes? b. Destruction of toxins. c. Catalyzing (speeding up) biochemical reactions. d. Acting as cell-surface receptors. d. Acting as intracellular signal-transduction messengers. 3. Distribution of a toxin throughout the body is accomplished primarily by the: a. liver. b. skeletal muscles. c. circulatory system. d. kidneys. e. lungs 4. Which of the body fluid compartments will a toxin have the most difficulty entering, and why?

5. When exposed to a toxicant, the dose an organism receives depends on which of the following? a. Exposure pathway b. Duration and frequency of exposure c. Chemical characteristics of the toxicant d. All of the above. 6. During lecture, we discussed the various routes by which toxins may enter the body and the advantages/disadvantages of each route. If you were an organism producing a toxin, which route would you most prefer to use for getting your toxin into another organism, and why? Which route would you least prefer to use, and why? Note: assume that having your toxin absorbed across the skin is not an option. If you’re stuck on this question, for 3 points, I’ll give you a hint. Just ask.

7. Suppose you’re in charge of the Rat Control Office in New York City, and you want to see if a new rat poison should be adopted for routine use. To help you reach a decision, you took a sample of 100 rats from the streets of NYC and each week gave them a progressively higher dose of the new poison, recording the number that were killed by each dose. Here are the resulting data, along with data from cats, dogs, and people:

Minimum Cats, Effective Dogs, Dose & (mg/kg) Rats People 0 0 0 10 0 0 20 0 0 30 5 0 40 24 0 50 40 0 60 24 0 70 5 5 80 0 24 90 0 40 100 0 24 110 0 5 120 0 0 a. What are the NOAEL (No Observable Adverse Effect Level) values for rats? For cats, dogs, and humans? Note: I want numerical values, not a definition. Rats: ______

Cats, dogs, and humans: ______

b. Are rats more – or less – susceptible to the toxin than cats, dogs, and humans? BRIEFLY justify your answer.

8. Give me two reasons that the elderly and very young tend to be more susceptible to many toxins.

9. Answer TWO (2) of the following:

 Using an appropriate graph, describe how researchers go about deciding if a particular drug is appropriate for use in treating a disease such as cancer.  Using an example that we discussed in class, discuss drug interactions, how they come about, and their implications for physicians who want to prescribe medicines to a patient.  Define and discuss biotransformation. Where in the body does most biotransformation occur, and how is it brought about? Define bioactivation, and describe an example.

Note: because I’m letting you choose which two questions to answer, I’ll be pretty exacting in my grading of your responses, so be sure you choose the two questions you sure you can answer best.