Pre-Lab AP Lab #12

Ecosystem Studies 1. Energy Flow 2. Chemical Cycling AP Lab #12 we will be able to study both cycles

AP LAB #12  Part a - Dissolved Oxygen in water  Part b – Primary Productivity  Part c – Identifying Aquatic Organisms

Vernier Probes  DO Probe = dissolved oxygen  Calculator will calculate %O2  Laptops to collect data.

Part a – Dissolved Oxygen  Objectives – 1. identify the effect of varying temperature on amount of dissolved oxygen in a water sample. 2. set up and calibrate Dissolved oxygen probe with calculator

Prediction 1. How will lower temperatures impact dissolved oxygen in water? o SLOW down gas molecules, more will remain in water rather than escape from surface. 2. How will higher temperatures impact dissolved oxygen in water?  SPEED up the interactions of the gas molecules with the surface  more molecules will escape.

12b - Primary Productivity Equation NPP = GPP – Rs Where...  NPP = Net Primary Productivity  GPP = Gross Primary Productivity  Rs = Respiration

Primary Productivity  The rate at which light energy is captured by autotrophs or primary producers.

Ps - photosynthesis 6 CO H 2 O + Light energy  C 6 H 12 O O H 2 O  First basic form of energy storage is termed Primary Production.  Total Ps = gross primary productivity

Primary Producers  Producers need energy to survive!  % of GPP is lost to Rs by the primary producers.  NPP = %  Animals - use only NPP, which limits the food webs.

Rs = Respiration  C 6 H 12 O O 2  6 CO H 2 O + ATP  Cellular respiration is required to release energy to do Ps  Natural Systems equilibrate  Ps : Rs

Interactions of both processes  Ps > Rs  excess energy  Growth or Reproduction  Ps = Rs  maintenance  Ps < Rs  consumption of stored biomass

Measuring Productivity  What substance is present in both Ps and Rs that can be measured in a high school setting?  CO 2 levels  O 2 levels

Ps vs. Rs O 2 levels CO 2 levels  Ps > Rs  Ps = Rs  Ps < Rs

Part C: Identifying Aquatic Organisms  Use Microscope  Use General Guide to Pond Life  Sketch and Identify organisms  Label sketches and note type  Producer  Consumer – specific type