Karteikarten
BIOL 354 Midterm Questions (set 1-5)
Karten in diesem Stapel (56)
- 1What's the difference between a xenobiotic versus anthropogenic?Xenobiotic = susbstance foreign to the organism
Anthropogenic = man-made substances
Both may be harmful or useful - 2What's the differencece between a toxin & toxicant? Give examples of each?Toxin = toxic substance made by living organisms (Ex. mycotoxin)
Toxicant = non-biological, man-made (anthropogenic) toxic substance (ex. PAH, PCBs, dioxins) - 3Who's the first toxicologist? What did this person hypothesize?The first toxicologist is Parceleus (swiss physician). Gave the hypothesis that "the dose makes the poison" (i.e. toxicity isn't just substance dependent but conc. dependent)
- 4On the dose response curve, what's on the x- and y-axis, respectively?X-axis = dose (conc.)
Y-axis = % viability - 5What was the focus of Rachel Carson's environmental toxicology movement?Insecticide DDT
- 6List the 4 basic steps of toxicant action1. Release into the environment
2. Exposure of toxicant to organism
3. Uptake by the organism
4. Adverse response elicited in organism - 7Name the 5 major classes of environmental contaminants1. Inorganics
2. Organics
3. Pesticdes
4. Complex effluents
5. Radioisotopes - 8What was the problem observed in chimney sweeps and the cause of this problem?Problem = Percival Potts observed rise of scrotal cancer
Cause = PAHs from the soot (as a result of incomplete combustion) - 9What was the cause for the "Mad Hatter" disease?Inhalation of mercury vapours
- 10What is the difference between a contaminant and a toxicant?Contaminant = could have adverse effects but may be needed by the organism
Toxicant = only has adverse effects on the organism - 11Name the 5 elements of a toxicity event.1. Generation of contaminants
2. Release of contaminants
3. Movement of contaminant to a receptor (organism)
4. Exposure to organisms at sufficient conc. and time
5. Organism response - 12What are the 2 source categories for toxicants? Give 3 examples & the type of each souce (7 total)Source category: 1) Point source (P) 2) Nonpointsource (NP)
Examples: agriculture (NP), industrial discharge (P), storm runoff (NP), aerosol (pesticdes) (NP) combustion (NP) - 13What 3 properties affect the fate of contaminants?1. Water solubility
2. Volatility
3. Environmental half-life - 14What's the relationship between toxicant dose and the type of response elicited?High conc. toxicant = acute response
Low conc. toxicant = chronic response
(see graph Y-axis dose, X-axis response time) - 15What's the unit for oral exposure? Topical exposure? Respiratory exposure?Oral = mass/wt organism (mg/kg)
Topical (aquatic) = mass/vol. (uM, ug/L)
Respiratory = mass/vol. (mg/L) - 16What are the 2 types of bioassays? From this, what 2 factors need to be considered for bioassays?Bioassays: Lethality and sublethality
Factors: Exposure time and dose concentration - 17What are modifying factors? Give the 2 types plus examples.Modifying factors = traits that can affect/alter toxicity of a chemical to an organism.
Types: biotic (age), abiotic (pH, O2) - 18What is included under the class "inorganic pollutants" (4 total)?Metals, metalloids, non-metallic inorganics,
gases - 19Name 2 functions of metals in living organisms.1. Enzyme cofactors
2. Cellular electrochemical gradient & balance (osomoregulation, membrane potential, signaling) - 20What's the key difference between Class A vs. B metals? (i.e. what classifies them?) Give examples of each class.Class A: Oxygen-seeking (Mg, Ca)
Class B: Sulfur-/nitrogen-seeking (Cd, Ni, Cu, Fe, Mn, Zn) - 21Why is Class A less toxic than Class B metals?Class A metal binds to O, which is abundant outside of organism. Inside the organism, there is also more O than S or N, which leads to less harmful, nonspecific binding. Class B metals bind to S/N, which are usually AA side chains, often in enzyme active sites and thus inhibit enzymatic functions.
- 22Name 3 anthropogenic sources of metals and 3 other sources of metals.Anthropogenic sources: Industrial effluent, metal mining, agriculture
Other sources: Paints, ash, lumber - 23Name 3 ways of how metals can elicit toxic effects1. Binding to enzymes
2. Interfere with essential metal uptake (ex. K or Ca)
3. Formation of reactive oxygen species to oxidize lipid bilayer or damage DNA - 24Why are organometals more hazardous than free metals? Explain with example.Organometals have organic groups that make them more lipophilic and suppports diffusion into biological membranes. An example of this is methyl mercury. Hg on its own cannot diffuse across membrane (has charge), but methylated form can easily cross lipid bilayer and accumulate in organism.
- 25Name and describe 3 environmentally important organometals.1. Tributyl tin (TBT) - antifouling compound
2. Tetraethyl lead - anti-knock compound in gasoline to increase efficiency
3. Methyl mercury - methylated by microorganisms; acts as neurotoxin which leads to behavioral and reporductive impairments - 26Name the 2 forms of ammonia - which is more hazardous and why?Ionized form (NH4+) and non-ionized form (NH3). NH3 is more hazardous because of its ability to diffuse across membrane.
- 27Name the point and nonpoint sources of ammonia.Point source: urban waste via landfills
Nonpoint source: farm land via fertilizer - 28What 2 factors affect unionized NH3 conc. and how?2 factors: pH and T
Increased pH and increased T both increase conc. of ammonia - 29Describe how unionized and ionized form of ammonia affect fish? (2 different mechanisms)Unionized: Crosses the lipid bilayer via passive diffusion
Ionized: uses the active transporter & moved inward as a mimic of K+ because of similar ionic radius (Na/K pump) - 30What are the outcomes of ammonia in fish? (4 in total)1. Increased energy demand (since it's exchanged for K+)
2. Intracellular pH disturbance that affect endo & exocytosis
3. Electrochemical disturbance
4. Inhibition of enzymatic reactions - 31What's the difference between Cl2 vs. Cl-? What are their targets?Cl2 is gaseous, Cl- is ionic.
Cl2 is used for water treatment to kill harmful microbes. Cl- has no effect on humans but is toxic to plants. - 32Where is cyanide found and why is it hazardous?Cyanide is generated via mining & metal processing. It inhibits oxidative phosphorylation (i.e. anything that has an electron transport chain)
- 33What characterizes an isotope? (Relative to the actual element)An isotope has different number of neutrons compared to original element
- 34What's the difference between isotopes and radioisotopes?Radioisotopes are unstable and spontaneously decays.
- 35Name all types of ionizing radiation.X-ray, gamma ray, alpha particles, beta particles
- 36Difference between what's measured by radioactivity vs. radiation dose?Radioactivity measures the conc. of the radiation.
Radiation dose measures the energy deposited in biological tissue (i.e. how much radiation was received) - 37Chernobyl accident releases 2x10^18 Bq radiation. Express this in curie and in DPM.5.4 x 10^13 curie
1.2 x 10^20 DPM - 38Poland expsoure to Chernobyl accident radiation was 1.2 mSv. How many rem is this?1Sv = 100 rem
0.12 rem - 39Name the functions of UVA vs. UVB.UVA is essential for DNA repair.
UVB damages DNA - 40How does UV radiation cause damage?UV radiation result in photosensitization damage by product of ROS and damaging DNA (thymine dimers)
- 41What makes up petroleum hydrocarbons (PHCs)Aliphatic and aromatic hydrocarbons of C5-C50 length
- 42Describe the toxicity of low MW vs. high MW PHC toxicity?Low MW = volatile, more bioavailable, more toxic, but most are consumed
High MW = adsorb onto sediments, reduced bioavailability, but more persistent - 43Name the PAHs with 2 fused rings, 3 fused rings (2), 4 fused rings (2)2 rings: naphthalene
3 rings: anthracenene and phenanthrene
4 rings: pyrene, chrysene - 44How is PAH produced (natural and anthropogenically?)PAH is mostly produced from combustion or incineration. Naturally: produced by volcanoes & forest fires. Anthropogenically: produced by gasoline combustion, metal refining, tobacco smoke, car exhaust
- 45What are the main environmental sinks for PAHs?Soil, sediment
- 46What is the source of PCB?Only anthropogenic origin. From insulating fluids of electrical equipments ad hydraulic fluids.
- 47What are the biological consequences of PCB?PCB is highly persistent (due to presence of Cl not degraded by biological systems). Interferes with endocrine system of vertebrates.
- 48Where do dioxins and furans come from?Mainly arise form production of PCB (ex. bleaching)
- 49What makes dioxins and furans so toxic to biological systems?Not easily metabolized or excreted and lead to high bioconcentration. Thus highly carcinogenic.
- 50What do PAH, PCB, dioxins and furans have in common that make them carcinogenic?All of these are planar, highly lipophilic molecules that partition into membrane and intercalate into DNA. Mistakes during repair = carcinogenic.
- 51Name the traits of an ideal pesticide1. Kills quickly
2. Persists only long enough to kill and breaks down to non-hazarouds compounds
3. Only kills target organisms and cheap to manufacture - 52What is the target and mode of action for DDT? Why is it banned in North America?Target = insects
MOA = penetrates waxy cuticle of insect exoskeleton & disrupt nerve function (via Na+ balance)
Banned because has adverse effect on fish-eating birds. - 53What is common about all insecticides?They are all neurotoxins
- 54What are the 2 modes of action for herbicides? Give example that uses each mode.1. Disruption of photosynthesis, broad-spectrum herbicide (ex. methyl viologen or atrazine)
2. Mimics auxin, plant growth hormone and disrupt growth, dicots (ex. phenoxyherbicides) - 55What is glyphosate and why is it a better alternative to other herbicide?Glyphosate = organophosphate that targets a plant enz.
Adv.= microbial degradation (i.e. not persistent); not toxic to mammals - 56What is the major concern of pharmaceutical products?Uncontrolled release into the environment (pharmaceuticals are biologically active)
Informationen
- Beschreibung
- Intro to toxicology, classes of toxicants/contaminants/pollutants
- Erstellt von
- Flora Dong · Okt 2017
- Aktualisiert
- 16 Okt 2017
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- 556
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