APES: Unit 8
The graph below shows the dose response curves for four different chemicals, labeled A — D, in a dose-response study on the effects of the chemicals on mortality in amphibians. All dose experiments began at 0 units of each chemical. Based on the data in the graph, which of the four chemicals is the most toxic to amphibians regardless of dose? A: A B: B C: C D: D
A: A The graph indicates that chemical A has the lowest threshold effect. It takes a lower dose of chemical A to produce an equivalent percent mortality than for any of the other chemicals to do so.
Which of the following approaches would best decrease the impact of frequent flooding in a community that is subject to the hazard of flooding? A: Construct wetland areas near the rivers and streams. B: Remove forested areas around all streams and rivers and change land use to agriculture. C: Increase the height of natural levees downstream from the community. D: Encourage developers to build housing developments on the floodplain.
A: Construct wetland areas near the rivers and streams. Wetlands absorb water during flooding. They capture water from rainfall events and slowly release floodwaters. Vegetation also decreases the speed of floodwaters over the floodplain.
Which of the following best describes why DDT is classified as a persistent organic pollutant? A: DDT is very stable, and as much as 50% of the original concentration can remain in the soil 15 years after the initial application. B: DDT can be used to control diseases, such as malaria and typhus, that are spread by insects. C: DDT is detected in food worldwide and the general human population is most commonly exposed to the toxin through food. D: DDT has both short-term acute and long-term chronic health effects in both humans and wildlife.
A: DDT is very stable, and as much as 50% of the original concentration can remain in the soil 15 years after the initial application. DDT is a synthetic, carbon-based molecule that is very stable (does not easily break down) in the environment. Its persistence means that it is found widely across the globe, even in regions where it was not used (such as the Arctic).
A: Fewer natural resources needed to be extracted. B: Groundwater contamination declined. C: Less carbon dioxide was released into the atmosphere. D: Less land was used for landfills.
A: Fewer natural resources needed to be extracted. Recycling of various materials decreases the need to extract certain materials from the environment. The increased recycling over time would have lessened the amount of natural resources that had to be extracted.
Which of the following strategies will best help to protect mangrove habitats? A: Limiting coastal development and maintain a shoreline buffer zone B: Increasing aquaculture operations to reduce overfishing C: Increasing subsidies for hydroelectric dam construction D: Encouraging land use changes in areas surrounding mangroves to shift to agriculture
A: Limiting coastal development and maintain a shoreline buffer zone The biggest threat to mangrove habitats is from development. Limiting that development and requiring a buffer zone will help preserve and protect the mangrove habitat.
Significant increases in water temperature can drastically change dissolved oxygen (DO) levels in a lake. Why does the combined effect of these two environmental changes result in algal blooms? A: Low dissolved oxygen leads to death for aerobic organisms, like fish, whose decomposition provides an overabundance of nutrients for the algae, resulting in the large blooms. B: Increased temperature causes an increase in metabolic rates of fish and insects. Increased metabolism results in increased waste from aquatic organisms, which provides energy for the algae to grow rapidly. C: Increased temperature and low dissolved oxygen drive aquatic animals out of the area. The lack of competition gives the algae more nutrients for reproduction.
A: Low dissolved oxygen leads to death for aerobic organisms, like fish, whose decomposition provides an overabundance of nutrients for the algae, resulting in the large blooms. Warm water holds less oxygen than cold water. The lack of oxygen kills aquatic life, which becomes a large food source for bacteria, which then release nutrients, resulting in large algal blooms.
The diagram below depicts a surface water source that has undergone cultural eutrophication. Based on the diagram, which of the following processes most likely caused the fish in the lake to die? A: The remains of the bottom-dwelling plants and algae decomposed, depleting the amount of oxygen in the water. B: The algal bloom at the surface released carbon dioxide into the water, suffocating the fish. C: The herbicides used on the corn crop were washed into the lake, accidentally poisoning the fish. D: Carbohydrates were released into the water when the bottom-dwelling plants died, increasing the amount of competition for food.
A: The remains of the bottom-dwelling plants and algae decomposed, depleting the amount of oxygen in the water. Bacteria and other decomposers use the dissolved oxygen in the water as they consume the remains of the bottom-dwelling plants and algae. Without enough dissolved oxygen in the water, fish can suffocate and die.
Cholera is an acute infection of the digestive system that is caused by the bacterium Vibrio cholerae. Infected individuals can experience a range of symptoms, including diarrhea, vomiting, muscle cramps, low blood pressure, rapid heart rate, and extreme thirst. If symptoms persist and severe dehydration results, an infected individual can die within hours of symptom onset. The diagram below shows how cholera is transmitted. A: V. cholerae is a microscopic bacterium that can survive in various aquatic environments for prolonged periods of time and can cause a delayed onset of visible symptoms. B: V. cholerae is a macroscopic bacterium that is easily detected in aquatic environments and causes rapid onset of symptoms. C: V. cholerae eventually becomes airborne and is spread through the inhalation of spores, causing a delayed onset of visible symptoms. D: V. cholerae is transmitted via an insect vector and often go
A: V. cholerae is a microscopic bacterium that can survive in various aquatic environments for prolonged periods of time and can cause a delayed onset of visible symptoms. According to steps 1, 5, and 6 of the diagram, these are all aspects of disease transmission that allow for V. cholerae to rapidly spread through a population. The bacterium is not easily detected, and infected individuals may unknowingly spread the disease if they have a delayed onset of symptoms.
Which of the following best describes the action of an endocrine disruptor? A: An endocrine disruptor attacks hormones that invade a body system and cause disease. B: An endocrine disruptor blocks the receptor protein binding site of a hormone so that the cell cannot receive a signal. C: An endocrine disruptor acts as an organic catalyst, produced by living things to regulate the rate of chemical reactions. D: An endocrine disruptor helps to transport substances, such as pesticides, in an organism following exposure.
B: An endocrine disruptor blocks the receptor protein binding site of a hormone so that the cell cannot receive a signal. Endocrine disruptors mimic or block hormones from cell receptors. They bind to receptor proteins and interfere with normal endocrine system function.
A biologist is studying a small food web in which phytoplankton are eaten by krill, krill are eaten by fish, and fish are eaten by seals. During their study of the ecosystem, the biologist discovers that PCBs are present in measurable levels in the water and wants to examine how PCBs could vary in different trophic levels. Which of the following best identifies a testable hypothesis for the study? A: Biomagnification will cause the phytoplankton outside the study area to have the highest amount of PCBs in their tissues. B:Biomagnification will cause the seals to have the highest amount of PCBs in their tissues. C: Bioaccumulation will cause the seals outside the study area to have the highest amount of PCBs in their tissues. D: Bioaccumulation will cause the fish to have the highest amount of PCBs in their tissues.
B: Biomagnification will cause the seals to have the highest amount of PCBs in their tissues. Biomagnification is an amplifying effect that occurs at the top of a food chain or food web. The seals are at the top of the web and would be expected to have the highest levels of PCBs in their tissues since PCB is a substance that would increase in concentration up the food web.
A scientist wants to study the effect of DDT in a fish-eating bird species. She measures a variety of variables in a population of birds over a period of ten years to determine how levels of DDT affect bird survival and reproduction. Which of the following identifies a scientific question she could ask to best evaluate the effect of DDT on the bird species? A: Is the bird species able to metabolize DDT faster than the fish the birds consume? B: Does the persistence of DDT lead to eggshell thinning or developmental deformities in the bird species? C: Has the decrease in DDT usage led to a decrease in DDT concentration in the tissues of fish-eating birds? D: How long does it take for DDT to break down once it is absorbed in the fatty tissues of the fish-eating birds?
B: Does the persistence of DDT lead to eggshell thinning or developmental deformities in the bird species? DDT is a substance that bioaccumulates in species because it is fat-soluble and cannot be excreted as fast as it is absorbed. Additionally, DDT can be biomagnified in a food chain. The effect of DDT (and other toxins) can include metabolic issues. In birds, there are links to DDT and eggshell thinning as a result of an alteration of calcium metabolism.
Which of the following is the most likely consequence of runoff transporting chemicals that are endocrine disruptors to a pond? A: Decreased turbidity in the pond B: Increased frequency of birth defects in fish populations in the pond C: Increased mutualistic relationships between fish and frog populations in the pond D: Increased dissolved oxygen in the pond
B: Increased frequency of birth defects in fish populations in the pond
Which of the following is a way to potentially eliminate one of the greatest threats to the world's mangrove wetlands? A: Increase desalination to reduce the effects of prolonged drought in mangroves. B: Integrate ecologically sound shrimp aquacultural practices with mangrove management. C: Construct dams in mangroves to increase sediment load and decrease pollution. D: Employ irrigation methods to address potential desertification of mangrove habitats.
B: Integrate ecologically sound shrimp aquacultural practices with mangrove management. Hundreds of thousands of acres of mangrove wetlands have been cleared for artificial lagoons for shrimp and fish farming, which is one of the greatest global threats to mangroves. By working toward sustainable shrimp farming, the mangrove will have less pollution and disease, while still providing economic benefits of shrimp harvest.
According to the World Health Organization, persistent organic pollutants (POPs) are found in nearly all tested organism tissues and environmental samples. Which characteristic of POPs accounts for their presence in living tissues and in environmental samples? A: POPs are lipophilic, which means that they can be stored in fatty tissues for long periods of time. B: POPs are released in to the air, water, and land, which allows them to be transported and incorporated in multiple ways. C: POPs are synthetic chemicals, so only humans and urban environments are exposed to the pollutants. D: POPs are organic compounds, so they can biodegrade easily and move through various environments.
B: POPs are released in to the air, water, and land, which allows them to be transported and incorporated in multiple ways. POPs are found in most environmental samples because they are globally distributed by air or water currents. Additionally, they can enter living organisms through exposure to contaminated air, water, or food.
A beach community was recently negatively affected by a hurricane. Community leaders are looking for a potential solution to prevent damage from future hurricanes. Below is a list of their concerns as well as how important each issue is to the community. Which of the following solutions would best address the issues of greatest concern in the community? A: Construction of a seawall B: Planting mangrove forests C: Construction of an offshore breakwater D: Adding large sand dunes
B: Planting mangrove forests Healthy mangrove forests provide homes for roosting bird species, protect coastal communities from storm surges, and provide a nursery habitat for juvenile coral reef organisms.
Which of the following practices would best help to protect against inland and coastal flooding in urban areas? A: Regulating the use of pesticides and fertilizers in agriculture B: Preserving wetland and coastal mangrove habitats C: Increasing the capacity of the sewer lines so they can handle a larger volume of water D: Straightening stream channels to increase stream flow
B: Preserving wetland and coastal mangrove habitats Wetlands and mangroves are crucial habitat for water storage, so the preservation of their habitats from loss and destruction will reduce flooding in urban areas.
Which of the following would best be described as a point source of pollution from a farm? A: Nitrogenous fertilizers added to drip irrigation used for growing crops B: Runoff from the waste lagoons of Concentrated Animal Feeding Operations, which enters local waterways after a flooding event C: Tractors and harvesters burning fossil fuels and releasing carbon dioxide and nitrous oxides into the atmosphere D: Particulate matter from bare soil on plowed fields entering the atmosphere from wind
B: Runoff from the waste lagoons of Concentrated Animal Feeding Operations, which enters local waterways after a flooding event Concentrated Animal Feeding Operations are one of the few agricultural point sources of pollution. Confining many animals to limited space concentrates their waste, making them a point source of pollution.
Scientists are interested in determining if selenium, from a nearby mine, magnifies in the tissues of fish living in a lake. Which of the following best describes a testable hypothesis for the study? A: Tissue from fish in the lake will have a higher level of selenium than tissue from fish in a nearby lake. B: Selenium will be at a higher concentration in fish tissue than in the tissue of fish prey. C: Fish will have a higher concentration of selenium than mercury in their tissues. D: Selenium will be at a higher concentration in acid mine drainage than in fish tissues.
B: Selenium will be at a higher concentration in fish tissue than in the tissue of fish prey. Comparing toxin levels in fish tissues to those of fish prey would allow the scientist to determine how much selenium magnifies as it moves up trophic levels in the food chain. Biomagnification occurs when the concentration of the chemical increases up the food chain, so it may be in lower concentration in the prey species, but it magnifies at higher trophic levels.
Which of the following statements best describes how the Clean Water Act legislation aims to protect wetlands from being lost? A: The Clean Water Act bans the draining of wetlands over five acres in size. B: The Clean Water Act requires wetlands to be constructed to mitigate the effect of newly drained wetlands. C: The Clean Water Act establishes standards for the quality of surface waters that must be continually monitored and reported. D: The Clean Water Act prohibits the use of wetlands for development and construction.
B: The Clean Water Act requires wetlands to be constructed to mitigate the effect of newly drained wetlands. The Clean Water Act stipulates that wetlands that are drained and destroyed must be replaced by newly constructed wetlands in order to mitigate the loss of ecosystem services provided by wetlands.
A massive bluegill fish kill was observed in a lake near a power plant during the winter months. It was determined that the plant was releasing large amounts of hot water into the lake. Which of the following explains what likely caused the death of so many bluegills in the lake? A: The increased water temperature caused dissolved oxygen levels to increase, leading to greater metabolic activity of catfish, which outcompeted the bluegill fish for resources. B: The influx of warmer water caused an unexpected increase in the metabolic rate of the bluegills, which led to increased physiological stress from limited resource availability. C: Rates of organic matter decomposition increased, which lead to an increase in dissolved oxygen and increased bacteria levels.
B: The influx of warmer water caused an unexpected increase in the metabolic rate of the bluegills, which led to increased physiological stress from limited resource availability. Fish are ectothermic, and metabolic rates are influenced by their surrounding temperature. Metabolic rates are low in the winter months in fish, but rates would increase with an influx of warm water, which could lead to exhaustion of available food supplies.
The two pie charts show municipal solid waste (MSW) in the United States, 2015. A: Glass B: Wood C: Metals D: Plastics
B: Wood Compared to the other choices, wood does not make up the largest percentage of MSW, but it is the best candidate for incineration because it is easily combustible and has less harmful air pollutants than other materials.
The graph below shows the LD50 for two different species of mice after being exposed to a mutagen for 30 days. Based on the data in the graph, which of the following should be used to calculate the difference in LD50 for the two different species of mice? A: (200mg - 100mg)/2 B: 490mg/50 - 575mg/50 C: 575mg - 490mg D: (600mg x 50)/30 days
C: 575mg - 490mg The LD50 for Species 1 is approximately 490mg and the LD50 for Species 2 is approximately 575mg, which would make the difference 85 mg, obtained by subtracting the two values.
The two pie charts show municipal solid waste (MSW) in the United States, 2015. A: Free or low-cost pickup of grass trimmings by municipal waste haulers B: Increased use of plastic packaging for consumer products C: Enacting a single-stream recycling program and providing bins to residential homes D: Digitization of news and use of e-mail for communication
C: Enacting a single-stream recycling program and providing bins to residential homes A single-stream recycling program allows for individuals to throw all recyclable waste, such as paper, glass, and plastic, into one large recycling bin. This would reduce any work required by individuals to prepare waste for recycling, thus making it easier for individuals to recycle.
A scientist is studying the correlation between air pollution and cardiovascular disease in humans. Which of the following measures would best show a link between air pollution and cardiovascular disease? A: Mortality rates from cardiovascular disease in populations in different countries B: Total number of emergency room visits by individuals with cardiovascular disease in urban areas compared to rural areas C: Occurrences of emergency room visits by individuals with cardiovascular disease on days with a high air quality index value D: Change in number of individuals with cardiovascular diseases over the past 50 years compared to levels of atmospheric carbon dioxide
C: Occurrences of emergency room visits by individuals with cardiovascular disease on days with a high air quality index value When the air quality index (AQI) is high (100−300), ranging from "Unhealthy for Sensitive Groups" to "Hazardous," there are increased cases of cardiovascular disease cases in emergency room visits as well as increased mortality rates.
Which of the following is a point source pollutant that would likely affect the ecosystem health of a coral reef? A: Small pieces of plastic washed in by local currents B: Runoff of oil from nearby urban highway systems C: Oil released from the broken hull of a shipwrecked tanker D: Excess nutrients introduced by fertilization of farmland
C: Oil released from the broken hull of a shipwrecked tanker A large amount of oil spilling from a damaged tanker as a result of a shipwreck would be considered a point source pollutant.
Which of the following correctly identifies an example of an endocrine disruptor and the effect it might have on the human body? A: High levels of lead in drinking water could lead to neurological damage. B: Exposure to radon in indoor air is linked to increased rates of lung cancer. C: Phthalates in cosmetics and shampoos reduce fertility. D: The bacterium E. coli found in vegetables causes abdominal cramping and vomiting.
C: Phthalates in cosmetics and shampoos reduce fertility. Phthalates are a group of chemicals that increase the flexibility of plastic and are found in many personal-care products such as cosmetics and shampoos. Exposure to phthalates is linked to endocrine disruption in humans and has been found to affect human reproduction and development.
The graph below depicts the dose response curves for three common bacteria and a newly discovered bacterium found in streams near certain agricultural properties. A: C. jejuni B: E. coli C: Salmonella spp. D: Newly discovered bacterium
C: Salmonella spp. Salmonella spp. has the highest probability of illness at 102 CFU with approximately 60%.
Based on the diagram, organic solids that have settled to the bottom of the treatment tanks in step B are transferred to which of the following for further processing? A: Screens B: Filter beds C: Sludge treatment tanks D: Effluent discharge
C: Sludge treatment tanks Organic solids that have settled during primary treatment are sent to the sludge treatment tank for breakdown through biological processes.
A scientist wanted to investigate the effect of tropospheric ozone on the respiratory function of mice. Twenty female mice were placed in one of five different field environments that mimicked the natural habitats of the mice. Each environment had a tube connected to it that would pump in a set level of ozone measured in ppm. In each field environment, the scientist measured the average respiratory output for the twenty mice over a three-month time frame. Which of the following describes the independent variable in the experiment? A: The simulated field environment that housed the group of twenty mice B: The respiratory output of each mouse C: The different levels of ozone introduced into the environments D: The use of female mice
C: The different levels of ozone introduced into the environments The ozone level was the only difference between each field environment. It was manipulated to examine the effect of ozone on respiratory output in mice, therefore serving as the independent variable.
Long Island Sound is a body of water off the northeast coast of the United States. Over nine million people live in the small watershed area that feeds into the sound. To determine the effect of the population density on the watershed, scientists measured the oxygen content of bottom waters in the sound. The data from late summer 2013 are displayed in the map below. A: The sound has high levels of dissolved oxygen as a result of storm water runoff from urban areas. B: The sound has high levels of phosphorus and nitrogen from an increase in the number of producers. C: The sound has large numbers of phytoplankton blooms that are decomposing and consumed by respiring bacteria. D: The sound has high numbers of respiring fish populations and very low turbidity.
C: The sound has large numbers of phytoplankton blooms that are decomposing and consumed by respiring bacteria. Nutrients in the runoff of a heavily populated area lead to large phytoplankton blooms. When the nutrients are consumed, the phytoplankton die and sink to the bottom, where they are decomposed by bacteria that consume oxygen. This leads to the decreased levels of dissolved oxygen shown in the image.
A scientist investigated the radiation sensitivity of different mammals to x-rays to determine the LD50 within 30 days. Results from the study are included below. Based on the LD50 data in the table, which of the following equations should be used to calculate how many times greater the resistance of a rabbit to x-rays is than that of a dog? A: 800−325 B: 800+325 C: 800×325 D: 800/325
D: 800/325 This equation shows the overall difference in the LD50 doses of x-ray radiation for the two different mammals, which does not show how many times greater the dose is for rabbits compared to dogs.
Which of the following correctly identifies both a nonpoint source and a point source of pollution? A: A B: B C: C D: D
D: D Urban runoff is considered a nonpoint source of pollution as it occurs as water runs across land or through the ground and picks up various pollutants. Exhaust from a city bus is considered to be point source of pollution as it is coming from an identifiable source (the tailpipe).
What is Primary Treatment of Tertiary Treatment? A: Wet scrubbers B: Filters C: Coagulants D: Disinfectants
D: Disinfectants Disinfection, usually using chlorine, ozone, or ultraviolet light, is referred to as the tertiary treatment step of sewage treatment. This process is effective at destroying bacteria before the water is discharged.
At what step in the diagram would wastewater most likely be treated with chlorine or UV light to remove bacteria? A: Before step A B: Between steps A and B C: Between steps C and D D: During step D
D: During step D Chlorine or UV light is used during tertiary treatment, or the final step, to kill a variety of pathogens. In order for this disinfection step to be effective, the wastewater must first have all solid wastes adequately removed.
Which of the following examples includes both a point and a nonpoint source of pollution? A: A factory smokestack and a sewage overflow B: Runoff from city streets and pesticides from agricultural fields C: Waste from animal feedlots and sediment from construction sites D: Fertilizer from suburban lawns and wastewater from a water treatment plant
D: Fertilizer from suburban lawns and wastewater from a water treatment plant Fertilizer runoff from suburban development is a nonpoint source because it originates from multiple sources. Wastewater from a water treatment plant is a direct source of pollution that comes from a single identifiable source.
Long Island Sound is a body of water off the northeast coast of the United States. Over nine million people live in the small watershed area that feeds into the sound. To determine the effect of the population density on the watershed, scientists measured the oxygen content of bottom waters in the sound. The data from late summer 2013 are displayed in the map below. A: Overfishing B: Plastic pollution C: Sewage treatment D: Restricted circulation
D: Restricted circulation The enclosed shape of the sound could result in reduced circulation, meaning that oxygen-rich waters would not reach bottom waters where phytoplankton do not photosynthesize. The shape could also prevent water movement from increasing the amount of oxygen in the water. This is the most likely factor to contribute to the hypoxic conditions in the sound.
Cholera is an acute infection of the digestive system that is caused by the bacterium Vibrio cholerae. Infected individuals can experience a range of symptoms, including diarrhea, vomiting, muscle cramps, low blood pressure, rapid heart rate, and extreme thirst. If symptoms persist and severe dehydration results, an infected individual can die within hours of symptom onset. The diagram below shows how cholera is transmitted. A: Disease transmission for cholera is through direct contact with infected individuals and is independent of sanitation conditions. B: V. cholerae grow rapidly in clear, moving water that has limited nutrients or wastes. C: Waste water treatment facilities that use high levels of chlorine to treat the outgoing municipal water supply have an increased risk of cholera outbreaks. D: Runoff from a nearby agricultural field pollutes a reservoir used for drinking water.
D: Runoff from a nearby agricultural field pollutes a reservoir used for drinking water. According to step 2 of the diagram, pollutants like nitrogen and phosphorus, which are common in agricultural runoff, would cause eutrophication in the reservoir. This could lead to an algal bloom, providing more food resources to any existing V. cholerae in the water and increasing its population size. If the water in the reservoir (with the bacteria) is used directly for drinking water, it could infect individuals in the community.
The graph below depicts the dose response curves for three common bacteria and a newly discovered bacterium found in streams near certain agricultural properties. A: If there are fewer than 102 colonies for all species in a drinking water sample, the water will be considered safe to drink. B: If C. jejuni is the only species of bacteria present in the drinking water sample, the water will be considered safe to drink at all doses. C: E. coli and Salmonella spp. would have the highest allowable dosage to meet the drinking water standards. D: The newly discovered bacterium would have the lowest allowable dosage to meet the drinking water standards.
D: The newly discovered bacterium would have the lowest allowable dosage to meet the drinking water standards. The newly discovered bacterium crosses 10% probability (0.1) at the lowest dose of all the bacterial species. Therefore, if drinking water standards are set by bacteria type, the newly discovered bacterium would have the lowest allowable dosage to meet the standards.
