Practice AP Environmental Science Unit 8 questions on aquatic pollution, wetlands, eutrophication, thermal pollution, waste, sewage, health, and pathogens.
Researchers are studying the stream ecosystem shown in the following diagram. They have identified five different zones based on the dissolved oxygen levels and biological oxygen demand as the water flows downstream. Biological oxygen demand is the amount of oxygen needed by bacteria and other microorganisms to break down organic material in water. Some of the most common fish and macroinvertebrate species found in each zone are listed in the diagram.
Dissolved Oxygen and Biological Oxygen Demand in a Stream Ecosystem
Based on the information in the diagram, identify the zone with the lowest level of dissolved oxygen..
Based on the information in the diagram, describe the relationship between biological oxygen demand and dissolved oxygen.
Based on the information in the diagram, identify the zone where there is most likely point-source water pollution discharged into the stream.
The research team is interested in investigating the relationship between dissolved oxygen levels and macroinvertebrate species richness in the stream. Researchers counted the number of macroinvertebrate species in zones A, B, and C during the summer months. The researchers selected zone A to serve as the control in the investigation.
Describe the reason the researchers selected zone A to serve as the control in the investigation.
The researchers decided to repeat their data collection during the winter months.
Explain how the modification to collect data in the winter months could alter the results of the investigation.
Stream ecosystems are affected by point-source organic pollution in a variety of ways.
Describe the effect that the introduction of raw sewage into the stream could have on the population of bacteria in the stream.
Identify an abiotic factor other than dissolved oxygen and organic pollution that could also influence the population size of bacteria in the stream.
Explain how persistent organic pollutants can affect higher trophic levels in an aquatic food web.
Begin your response to this question at the top of a new page in the separate Free Response booklet and fill in the appropriate circle at the top of each page to indicate the question number.
A doctor tells his patient that she is exhibiting the effects of an endocrine disrupter on her body. What part of the body would the endocrine disruptor be impacting?
Cardiovascular system
Skin
Hormones
Nervous system Use the graph below to answer questions 13-14.
Read the following article from the Fremont Daily Times and answer the questions that follow.
Fremont Daily Times
Scientists Discuss Threats from Plastic Pollution
In testimony before the United States Senate Committee on Environment and Public Works, Dr. Duke Ewoldsen, an eminent toxicologist, discussed a new water pollutant that threatens aquatic life: microbeads. Ewoldsen noted that while posing a different threat than more conventional water pollutants such as nitrates, phosphates and PCBs, tiny beads of plastic contained in many products, especially cosmetics, now threaten plankton and small fish that ingest the particles because they mistake them for food. The microbeads cannot be digested and can fill or block the digestive tracts of the fish, leading to starvation. In addition, surfaces of these small spheres can adsorb organic pollutants such as PCBs and dioxin.
When asked about steps to reduce this threat, Ewoldsen noted that the beads are so small that they are not easily removed by wastewater treatment plants and thus often enter aquatic ecosystems in wastewater discharges.
Describe TWO effects that ingesting microbeads has on aquatic organisms.
Dr. Ewoldsen states that nitrates pose different threats to aquatic ecosystems than microbeads do. Describe how nitrate levels can negatively affect water quality in some aquatic ecosystems.
While wastewater treatment plants are ineffective at removing microbeads, they are very effective at removing large pieces of plastic waste and other pollutants.
Identify one way large pieces of plastic are removed from wastewater during primary treatment.
Prior to discharge, wastewater is often disinfected. Identify one technique commonly used to disinfect wastewater.
Sludge or biosolids produced during the wastewater treatment process can be spread on agricultural fields. Identify one advantage and one disadvantage of this practice.
Coastal ecosystems are threatened by other human activities in addition to wastewater disposal. Mangrove swamps are one such threatened ecosystem.
Provide one reason why mangrove trees are being removed by humans.
Identify one ecosystem service provided by intact mangrove ecosystems.