Photosynthesis & Gross Primary Productivity:
Where the base of the food web gets its energy
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Task 1: Create a flipAnimate video to demonstrate the following steps:
Image source: https://www.carlsonstockart.com/photo/leaf-structure-anatomy-illustration/
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Task 2: What are these? Why are they important? Find out what species they are and explain why they are important.
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Extension:
A blooming history: Photosynthesis |
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The primary productivity of a community is the amount of biomass produced through photosynthesis per unit area and time by plants, the primary producers. Primary productivity is usually expressed in units of energy (e.g., joules m -2 day -1) or in units of dry organic matter (e.g., kg m -2 year -1). Globally, primary production amounts to 243 billion metric tons of dry plant biomass per year. The total energy fixed by plants in a community through photosynthesis is referred to as gross primary productivity (GPP). Because all the energy fixed by the plant is converted into sugar, it is theoretically possible to determine a plant's energy uptake by measuring the amount of sugar produced. A proportion of the energy of gross primary productivity is used by plants in a process called respiration. Respiration provides a plant with the energy needed for various plant physiological and morphological activities. (http://www.physicalgeography.net/fundamentals/9l.html, 2019)
The general equation for respiration is:
The general equation for respiration is:
C6H12O6 + 6O2 >>> 6CO2 + 6H2O + released energy
Subtracting respiration from gross primary production gives us net primary productivity (NPP), which represents the rate of production of biomass that is available for consumption (herbivory) by heterotrophic organisms (bacteria, fungi, and animals).
Globally, patterns of primary productivity vary both spatially and temporally. The least productive ecosystems are those limited by heat energy and water like the deserts and the polar tundra. The most productive ecosystems are systems with high temperatures, plenty of water and lots of available soil nitrogen. Table 9l-1 describes the approximate average net primary productivity for a variety of ecosystem types.
Globally, patterns of primary productivity vary both spatially and temporally. The least productive ecosystems are those limited by heat energy and water like the deserts and the polar tundra. The most productive ecosystems are systems with high temperatures, plenty of water and lots of available soil nitrogen. Table 9l-1 describes the approximate average net primary productivity for a variety of ecosystem types.
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Measuring Productivity
BOD is measured in ppm (mg/litre). It is measured at 20ºC over five days (source Tomkins, Biology at Work, CUP). As very polluted water will take up the oxygen very fast you need to dilute it down to test it. (For example:- Dilute the very polluted sample with an equal volume of distilled water would necessitate multiplying the final result by two.)
Quoted BODs are upland stream, 1 lowland stream, 3 Lowland river 5 treated sewage 20 crude sewage 300 pig slurry 30,000 silage liquor 60,000 |
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Secondary productivity
If energy can never be created nor destroyed, where does it go?
Task: Make a model in your book to show how energy travels through the biome from sun to producer to top predator. Use the 10% rule to show your model. Use the following species:
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