UNIT 4 - Flows of Energy and Matter
Significant ideas:
- Photosynthesis and respiration play a significant role in the flow of energy in communities.
- Ecosystems are linked together by energy and matter flows.
- The Sun’s energy drives these flows. Humans are impacting the flows of energy and matter both locally and globally.
Knowledge and Understanding:
- Respiration and photosynthesis can be described as processes with inputs, outputs, and transformations of energy and matter.
- Respiration is the conversion of organic matter into carbon dioxide and water in all living organisms, releasing energy. Aerobic respiration can simply be described as:
- During respiration large amounts of energy are dissipated as heat, increasing the entropy in the ecosystem while enabling the organisms to maintain relatively low entropy/high organization.
- Primary producers in the majority of ecosystems convert light energy into chemical energy in the process of photosynthesis.
- The photosynthesis reaction is:
- Photosynthesis produces the raw material for producing biomass.
- As solar radiation (insolation) enters Earth’s atmosphere some energy becomes unavailable for ecosystems as the energy is absorbed by inorganic matter or reflected back into the atmosphere.
- Pathways of radiation through the atmosphere involve a loss of radiation through reflection and absorption.
- Pathways of energy through an ecosystem include:
- conversion of light energy to chemical energy
- transfer of chemical energy from one trophic level to another with varying eficiency
- overall conversion of ultraviolet and visible light to heat energy by an ecosystem
- re-radiation of heat energy to the atmosphere.
- The conversion of energy into biomass for a given period of time is measured as productivity.
- Net primary productivity (NPP) is calculated by subtracting respiratory losses (R) from gross primary productivity (GPP).
- Gross secondary productivity (GSP) is the total energy/biomass assimilated by consumers and is calculated by subtracting the mass of faecal loss from the mass of food eaten.
- Net secondary productivity (NSP) is calculated by subtracting respiratory losses (R) from GSP.
- Maximum sustainable yields are equivalent to the net primary or net secondary productivity of a system.
- Matter also flows through ecosystems linking them together. This flow of matter involves transfers and transformations.
- The carbon and nitrogen cycles are used to illustrate this flow of matter using flow diagrams. These cycles contain storages (sometimes referred to as sinks) and flows that move matter between storages.
- Storages in the carbon cycle include organisms, including forests (organic), atmosphere, soil, fossil fuels, and oceans (all inorganic).
- Flows in the carbon cycle include consumption (feeding), death, and decomposition, photosynthesis, respiration, dissolving, and fossilization.
- Storages in the nitrogen cycle include organisms (organic), soil, fossil fuels, atmosphere, and water bodies (all inorganic).
- Flows in the nitrogen cycle include nitrogen fixation by bacteria and lightning, absorption, assimilation, consumption (feeding), excretion, death, and decomposition, and denitrification by bacteria in water-logged soils.
- Human activities such as burning fossil fuels, deforestation, urbanization, and agriculture impact energy flows as well as the carbon and nitrogen cycles.
Content |
Classwork/Homework |
Support Resources |
Photosynthesis and Respiration |
|
|
Earths Energy budget |
Energy budget of the earth - make your own sankey diagram to represent the energy budget from the ppt on slide 2: 3. Flows of energy and biomass 4. Example energy flow diagram |
|
Productivity |
Make notes on productivity: 5. Productivity Complete the question on the following worksheets: 6. Productivity worksheet 1 7. Productivity worksheet 2
|
|
Carbon cycle |
Make notes and complete your own carbon cycle diagram: 8. Carbon cycle activity 9. Carbon cycle worksheets To test your comprehension you will now complete a web activity: 10. Carbon cycle web activity using the windows2theuniverse site 11. Carbon cycling in depth
|
|
Nitrogen cycle |
Use the following flash animation to follow the stages of the nitrogen cycle:
|
|
Measuring primary productivity |
You will first complete the virtual LabBench activity as an introduction to an open inquiry.If you have time, you will learn how to calibrate the dissolved oxgen probe, set up the logger pro and measure O2 in water samples |
Value |