Pre-Lab AP Lab #12

Ecosystem Studies1. Energy Flow2. Chemical Cycling

AP Lab #12 we will be able to study both cycles

AP LAB #12Part a - Dissolved Oxygen in waterPart b – Primary ProductivityPart c – Identifying Aquatic

Organisms

Vernier ProbesDO Probe = dissolved oxygenCalculator will calculate %O2Laptops to collect data.

Part a – Dissolved OxygenObjectives – 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

Prediction1. 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 ProductivityEquation NPP = GPP – Rs

Where . . .NPP = Net Primary ProductivityGPP = Gross Primary ProductivityRs = Respiration

Primary Productivity The rate at which light energy is

captured by autotrophs or primary producers.

Ps - photosynthesis

6 CO2 + 12 H2O + Light energy C6H12O6 + 6 O2 + 6 H2O

First basic form of energy storage is termed Primary Production.Total Ps = gross primary productivity

Primary ProducersProducers need energy to

survive!50 - 90% of GPP is lost to Rs by

the primary producers.NPP = 10 - 50%Animals - use only NPP, which

limits the food webs.

Rs = Respiration

C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATP

Cellular respiration is required to release energy to do Ps

Natural Systems equilibratePs : Rs

Interactions of both processes

Ps > Rs excess energyGrowth or Reproduction

Ps = Rs maintenancePs < Rs consumption of

stored biomass

Measuring ProductivityWhat substance is present in

both Ps and Rs that can be measured in a high school setting?

CO2 levels

O2 levels

Ps vs. RsO2 levels CO2

levels

Ps > RsPs = Rs Ps < Rs

Part C: Identifying Aquatic OrganismsUse MicroscopeUse General Guide to Pond LifeSketch and Identify organismsLabel sketches and note type

ProducerConsumer – specific type