Biology 5868 ID Exam 2 April 6, 2007

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1 Ecotoxicology Name KEY Biology 5868 ID Exam 2 April 6, 2007 Be as specific as possible for all answers. Most of the questions have multiple parts; make sure to answer each part! Use diagrams, flowcharts, and formulas where appropriate. Use the back of the pages if necessary (make sure to indicate the question being answered). Fill in. (1 point per answer) 1. What two assumptions are made in order to conduct a valid ANOVA test? (2) 1. equal variances 2. normal distribution 2. List the following in order of increasing concentration: NOEC, LOEC, MATC (1) NOEC>MATC>LOEC 3. List two triggers for carcinogenesis. (2) mutations, chromosomal rearrangements, retroviruses, etc. 4. Two toxic compounds may potentiate each other s effects. True or False? (1) 5. In designing a toxicity experiment, one should use a (high/medium/low) biomass per test unit? (1) 6. Assuming that ANOVA testing indicates differences between treatment groups, list one type of post ANOVA test used in hypothesis testing. (1) Dunnett s, student s t, William s, etc. 7. List two factors regarding data from toxicity tests that are needed to determine which method of estimation of LC 50 will be used. (2) N, replicates, concentrations used, etc. 8. Raw data is often transformed to allow it to fit into a normal distribution. True or False? (1) 9. A chemical that causes chromosomal damage is called a _clastogen. (1) 10. List two potential behavioral biomarkers. (2) avoidance, activity levels, feeding, learning, predation, etc. 11. If Toxicant A induces a 10% reduction in a particular biomarker, and Toxicant B produces a 30% reduction in the same biomarker, what reduction would the combination of both produce in an organism under the simple comparative effect model? If the two toxicants acted antagonistically, would the reduction in the biomarker activity be greater or less than that expected under the simple comparative effects model? (2) 1. 30% 2. less Definitions Define any six of the following terms. (3 points each) 12. Teratogenic index (TI) TI = LC 50 /TC 50 = median lethal dose divided by median teratogenic dose; higher TIs indicate developmental toxicity 13. FETAX Frog Embryo Teratogenesis Assay Xenopus a 96 h static toxicity test designed to detect teratogenic agents using early Xenopus larvae 1

2 14. Hormesis A phenomenon in which low doses of a putative toxicant enhances or stimulates growth, survival, or the appearance of other biomarkers. 15. Acclimatization Modification of biological functions to maintain or minimize deviations from homeostasis; specific for field settings. 16. Sister chromatid exchange Normal exchange of chromosomal material (a.k.a. crossing over) during mitosis. 17. Ecological mortality Toxicant induced diminution of fitness equivalent to somatic death. 18. Fluctuating asymmetry Deviations from perfect bilateral symmetry; thought to reflect perturbations in normal developmental processes. Short Answer. Answer any six of the following questions. Note describe requires more than simply listing answers. (6 points each) 19. Carcinogenesis involves initiation and promotion. Differentiate between these two processes and give an example of a toxicant that induces each. An initiator stimulates a cell to become a latent cancer cell; while a promoter stimulates latent cancer cells to grow and proliferate. initiators: benzo[a]pyrene, other PAHs, dioxin promoters: hormones, growth factors, EDCs 20. What does the statement sublethal effects may have lethal consequences in an ecological context mean? Toxicant effects that decrease fitness may prevent individuals from successful reproduction/rearing of young, resulting in the failure of continuation of that genotype. 21. Organisms exposed to chemical X showed a reduced adenylate energy charge. Define this term and describe what the overall effect of a reduction in the AEC might have on the organism. AEC = ATP + ½ADP/ATP + ADP + AMP This equation relates to the balance between anabolism and catabolism. Higher AEC means more energy available for anabolic processes 2

3 22. A set of toxicity tests with nominal toxicant concentrations of 0.2, 2.0, 20, and 200 µg/l was measured with actual concentrations of 0.1, 1.5, 17, and 185 µg/l. If the possibility of measurement error or errors in the addition of the chemicals is eliminated, provide two possible explanations as to why the measured concentrations were less than the nominal values. solubility problems compound sticks to the container; effectively removes it from solution evaporation/volatility metabolism degradation 23. List two potential advantages and two potential disadvantages of using growth as a response variable (biomarker) in sublethal toxic effects assays. Advantages: easy to measure integrates biochemical and physiological pathways related to fitness often shows dose response Disadvantages thresholds hormetic effects not specific 24. Describe the difference between organizational and activational endocrine disrupting chemical effects. Give an example of each. Organizational effects are those that modify structures or developmental pathways; e.g. cell and tissue differentiation Activational effects are those that modify programmed responses to internal or external cues; e.g. reproduction, metamorphosis 25. You suspect that a chemical may be exerting its toxic effect on an organism s DNA. Describe two different methods of assaying for DNA damage. Chromosome staining karyotyping or banding will indicate deletions, duplications, etc. Flow cytometry indicates amount of DNA in a cell or tissue; detects ploidy changes 32 P nucleotide labeling combined with chromatography detects adducts Single cell alkaline DNA assay (Comet assay) detects chromosomal breakage 26. Define the General Adaptation Syndrome and briefly describe the characteristics of its three phases. The GSA is a specific suite of physiological responses exhibited in organisms under generalized stress. Alarm reaction catecholamine release glucocorticoid release Adaptation (resistance) hypertrophy, atrophy Exhaustion depletion of reserves failure to compensate 3

4 Short Essay. Answer question 27 and one of questions 28 and 29. (15 points each) 27. You are in charge of designing a toxicity test for compound X, which has been found in a nearby lake at concentrations between ppb (µg/l). Compound X is a suspected carcinogen and a suspected teratogen, but is not lethal to aquatic vertebrates at concentrations below 1000 ppb. The workspace available for your test limits you to 24 exposure units (fish tanks), but otherwise, you have all other resources that you may need to conduct the test. Design a toxicity test that will provide data on the possible effects of compound X on one of its suspected toxicological aspects. Describe and justify in detail (i.e. give the reasons why you chose): the type of test length of test test organism the number of organisms used concentration regime replicates response variable Type of test: static, static renewal, or flow through Length of test: at least through birth of young (for teratogenesis) Test organisms: vertebrates; fish or amphibians Number: lowest viable number/tank (replicate) Concentration regime: should flank concentrations found in the environment; i.e. [low] < 10 µg/l [high] > 100 µg/l include control (0 µg/l) Replicates: split the 24 exposures into even portions (including controls); e.g. 6 concentrations x 4 replicates each 8 concentrations x 3 replicates each Response variables: 1) cancerous tumors 2) malformations (in f 1 generation) 4

5 28. Toxicity tests have been conducted on three compounds, designated square, diamond, and circle, which have been found in the environment. Using data from the graph, answer the following questions: A) What are the LC 50 s of each compound? B) What are the LC 15 s of each compound? C) Which should be considered the most potent compound? Why. D) What can be speculated regarding mechanisms of action of the respective toxicants? Percent mortality A) LC 50 square = 33 μg/l LC 50 diamond = 33 μg/l LC 50 circle = 47 μg/l B) LC 15 square = 14 μg/l LC 15 diamond = 23 μg/l LC 15 circle = 29 μg/l toxicant concentration (µg/l) C) Square is the most potent compound because it is far more toxic at lower concentrations (e.g. LC 15 = 14 μg/l) than the other two compounds. D) Square and circle have the same general pattern and slope, and therefore probably have similar or identical modes of action; diamond likely has a different mode of action. 5

6 29. Organs and organ systems are often susceptible to toxicological processes. For the following organs, list A) one toxin/contaminant that is known to affect the organ B) the mechanism of exposure for the toxicant C) one possible response of the organ to the toxicant organs: lungs, liver, kidney lungs: liver: A) asbestos, ozone, sulfuric acid B) airborne exposure C) metabolic responses include biotransformation tissue responses include fibrosis (emphysema), removal (via ciliary movement) A) carbon tetrachloride, arsenic, vinyl compounds B) exposure via bloodstream C) metabolic responses include biotransformation/biodegradation tissue responses include hypertrophy, cirrhosis, fibrosis kidney: A) trichloromethane, carbon tetrachloride, methoxyfluorane, metals (e.g. Pb, Cd, Hg) B) exposure via bloodstream and filtering/reabsorbtion C) metabolic responses include metabolism tissue responses include cancers, 6

5. Which graph represents a population that grew and is maintained at the carrying capacity of its ecosystem?

5. Which graph represents a population that grew and is maintained at the carrying capacity of its ecosystem? Date: Pd. Regents Review Assignment #5 Living Environment 2 Part A Questions 1. Which structures carry out life functions within cells? (1) tissues (3) organelles (2) organ systems (4) organs 2. The sorting