Practice AP Environmental Science questions on aquatic pollution, coral reefs, oil spills, dead zones, sediment, heavy metals, mercury, and litter.
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.
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.
Identify an abiotic factor other than dissolved oxygen and organic pollution that could also influence the population size of bacteria in the stream.