Posts Tagged ‘inputs’

  • Outline the concept and characteristics of systems.
System: Assemblage of parts and relationships between them, which together make up a whole.
The components are connected together through the transfer of energy and matter, with all parts linking and effecting eachother.
Examples of these are:
  • atoms
  • molecules
  • cells
  • organs
  • organ systems
  • communities
  • ecosystems
  • biomes
  • earth
  • solar systems
  • galaxies
  • universes
Systems consist of:
  • storages ( of matter and energy )
  • flows ( inputs into the system, output from the system )
  • processes (which transfer or transform energy or matter )
  • feedback mechanisms that maintain stability and equilibrium
System diagrams consist of: 
  • boxes show storages
  • arrows show flows (inputs/outputs)
Diagram can be labelled with the processes on each arrow:
  • Photosynthesis – transformation of CO2, H2o and light into biomass and oxygen O2
  • Respiration – transformation of biomass into CO2 and water
  • Diffusion – movement of nutrients and water
  • Consumption – tissue transfer from trophic level to another
  • Apply the systems concept on a range of scales.
There are different scales of systems; there can be small-scale local ecosystem, large ecosystem as a biome, and global ecosystems.
For example: Forests contain many small-scale ecosystems.
  • Define the terms open system, closed system and isolated system.
Open: exchanges matter and energy between the system. They are organic and must interact with environment to obtain new matter and energy. Ex: People are open systems.
Closed: exchanges energy but not matter. Ex: the earth can be seen as a closed system.
Isolated: Neither energy or matter is exchanged. But these systems do not seem to exist. However the universe could be looked at as an isolated system,
  • Describe how the first and second laws of thermodynamics are relevant to environmental systems.
First law:
  • Energy is not created nor destroyed
  • Energy can only change from one to another
  • Ex: solar radiation -> sugars -> chemical energy -> chemical energy again
  • Energy has only moved and changed form
Second law:
  • not efficient energy (the more processes/transfers the less energy)
  • transformations lead to energy loss
  • living systems are only maintained through constant input of new energy from the sun
  • energy= work+heat
  • Explain the nature of equilibria.
Steady-state equilibrium:
Is the common property of most open systems in nature. There is a tendency in natural systems for the equilibrium to return after the disturbances, but some systems (succession) may go through long-term changes to keep their equilibrium while keeping their integrity.
Open systems have steady-state equilibrium, where any change to a stable system returns to the original equilibrium after the disturbance.
Stable changes then goes back to the normal state.
Unstable changes and does not go back to the normal state.
  • Define and explain the principles of positive and negative feedback.
Negative feedback: tends to damp down, neutralize or counteract any deviation from an equilibrium, and promotes stability.
Positive feedback: increases change in a system and deviation away from a equilibrium.
A system may include both feedbacks.
  • Describe transfer and transformation processes.
Both material and energy move or flow throw ecosystems.
Transfers: normally flow through a system and involve a change in location. When the flow does not involve a change in form just location.
Ex: Material through biomass, and energy movement.
Transformations: lead to an interaction within a system in the formation of a new and product, or involve a change of state. A flow involving a change in form.
Ex: Matter and energy transformations, energy to matter transformations.
  • Distinguish between flows (inputs and outputs) and storages (stock in relations to systems)
Inputs and outputs from systems are called flows and represented by arrows in system diagrams. The stock held within a system is called the storage and is represented through boxes.
  • Construct and analyse  quantitative models involving flows and storages in a system.

  • Evaluate the strengths and limitations of models.
Pros: 
  • allow scientist to predict/simplify complex systems
  • inputs can be changed and outcomes examined without having to wait for real events.
  • results can be shown to scientists and the public
Cons:
  • might not be totally accurate
  • rely on the expertise of people making them
  • different people may interpret them in different ways
  • vested interests might hijack them politically
  • any model is only as good as the data goes in and these may be suspect
  • different models may show different effects using the same data

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  • Explain the role of producers, consumers and decomposers in the ecosystem.
Producer: can make their own food, as they use sunlight to make food and are called  the basis of every ecosystem which helps the rest of the species through input of energy and new biomass. This all happens through photosynthesis which is the process when the producer uses the sun for energy.
Consumer: feed on other organisms, they do not contain photosynthesis pigments so they cannot make their own food. They have to get energy, minerals and nutrients by eating other organisms. This makes the heterotrophs. Herbivores feed on autotrophs, carnivores on other heterotrophs and omnivores on both.
Decomposer: get their food from the breakdown of a dead organism matter. They break down tissue and release nutrients for absorption by other producers. Decomposers also improve the nutrient capacity in the soil by breaking down the organic material.
  • Describe photosynthesis and respiration in terms of inputs, outputs and energy transformations.
Photosynthesis: needs carbon dioxide, water, chlorofyll and certain visible wave lengths of light to produce organic matter and oxygen.
  • inputs: sunlight as energy resource, carbon dioxide and water
  • processes: chlorofyll traps sunlight; energy is used to split water molecules; hydrogen from water is combined with carbon dioxide to produce glucose.
  • outputs: glucose used as an energy source for the plant and as a building block for other organic molecules; oxygen is released to the atmosphere through stomata.
  • transformations: light energy is transformed to store chemical energy.
Respiration: needs organic matter and oxygen to produce carbon dioxide and water.
  • inputs: glucose and oxygen
  • processes: oxidation processes inside cells
  • outputs: release of energy for work and heat
  • transformations: stored chemical energy to kinetic energy and heat
  • Describe and explain the transfer and transformation of energy as it flows through an ecosystem.
Not all solar radiation ends up being stored as biomass. Losses include_
  • reflection from leaves
  • light not hitting chloroplasts
  • light of the wrong wavelengths (not absorbed by chloroplast pigments)
  • transmission of light through the leaf
  • inefficiency of photosynthesis
In this diagram we can see the energy flow through an ecosystem.
  • Describe and explain transfer and transformation of materials such as they cycle within an ecosystem.
The Carbon Cycle:
The Hydrological cycle:

The nitrogen cycle:
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  • Define the terms gross productivity, net productivity, primary productivity, and secondary productivity.
*Productivity is production per unit time.
Primary productivity is the gain by producers (autotrophs) in energy or biomass per unit area per unit time. It is when solar energy is converted, it depends on the amount of sunlight the ability of the producers to use energy to synthesize organic compounds and the availability of other things needed for growth, like minerals and nutrients.
Primary production is highest were conditions for growth are optimal, where there are high levels of insolation, good water supply, warm temperatures and high nutrient levels.
You can then divide primary productivity into gross and net profits.
*GROSS is the income
*NET is the incomes minus costs
Secondary productivity depends on the amount of food there is and the efficiency of the consumers turning this into new biomass. Unlike the primary productivity net productivity involves feeding or absorption.
Gross productivity (GP): The total gain in energy or biomass per unit area per unit time.
Net productivity (NP): The gain of energy or biomass per unit area per unit time remaining after allowing for respiratory losses. It is the energy left for the next trophic level to consume.
  • Define the terms and calculate the values of both gross primary productivity and net primary productivity from given data.
Gross primary productivity (GPP): is gained through photosynthesis in primary producers.
Net primary productivity (NPP): is the gain by prodicers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses. (Available for consumers in ecosystem)
Productivity calculation:
Primary productivity:

where R = energy used in respiration
NPP = GPP – R
  • Define the terms and calculate the values of both gross secondary productivity and net secondary productivity from given data.
Gross secondary productivity(GSP): is gained through absorption in consumers.
Net secondary productivity(NSP): The gain by consumers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses.
Secondary productivity:
NSP = GSP – R
GSP = food eaten – faecal loss
where R = respiratory loss