Dissolved Oxygen (Lab 12)
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| Link to the Dissolved Oxygen
and Primary Productivity AP Bio Lab Lab Activity (Local Lab) Link to the Dissolved Oxygen and Primary Productivity Lab Results Lab Twelve Review Activity Lab 12 Review PowerPoint (modified from pdf file posted by Glen Cochrane at Half Hollows High School) |
Key Concepts
Dissolved Oxygen Availability
Factors that influence the amount of oxygen dissolved in water are: (1) Temperature: As water becomes warmer, its ability to hold oxygen decreases. (2) Photosynthetic activity: In bright light, aquatic plants are able to produce more oxygen. (3) Decomposition activity: As organic material decays, microbial processes consume oxygen. (4) Mixing and turbulence: Wave action, waterfalls, and rapids all aerate water and increase the oxygen concentration. (5) Salinity: As water becomes more salty, its ability to hold oxygen decreases.Primary Productivity
Primary productivity is the rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem.
Gross Productivity
Gross productivity is the entire photosynthetic production of organic compounds in an ecosystem.
Net Productivity
Net productivity is the organic materials that remain after photosynthetic organisms in the ecosystem have used some of these compounds for their cellular energy needs.
Lab Design
In the first part of the laboratory, you measure dissolved oxygen in water at different temperatures. Many kits and testing procedures are available for measuring dissolved oxygen.
A nomograph is used to measure how much oxygen water can hold. (Saturation Levels)
In the next part of the laboratory you monitor the effect of varying light levels on dissolved oxygen in an algae-rich water culture.
The amount of light available for photosynthesis drops off sharply with increasing depth in an aquatic environment. You model this condition by wrapping water-sample bottles with increasing layers of screen.
The last part of the lab occurs after 24 hours. Measure the amount of oxygen present of photosynthesis and respiration under the light conditions in each bottle.
Analysis of Results
You will analyze the six factors that influence the amount of oxygen dissolved in water. Refer to the Key Concepts.