B7.4 Learning from Nature

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  • Created by: Lili
  • Created on: 12-06-13 19:39
What is Meant by an Open-Loop System? (Give Example)
A system with many inputs and losses (outputs) - Little is recycled. (Intensive farming with high input of fertiliser and fossil fuels, the products are removed or eaten)
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What is Meant by a Closed-Loop System?
A system in which there is little input and the wastes from one process become the substrate for another process.
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Give an Example of a Closed-Loop System.
A natural eco-system in which plants remove nutrients from the soil and return them when the leaves drop off and decay.
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Which Type of System do Humans Often Create?
Open-Loop Systems
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What is Meant by a Sustainable Process?
A process which can be maintained without damage to the environment.
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Explain Why Human Systems are Often Not Sustainable?
They take too much material from the environment, or add to much waste to the environment.
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Why are Eco-Systems Often Not Perfectly Closed-Loops?
There are losses due to wind or water carrying materials away.
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Explain Why the Input to an Eco-System Should Equal the Losses.
So that there are no overall losses or gains and the system is sustainable.
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What is the Source of Energy for All Eco-Systems?
The Sun
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How does Burning Fossil Sunlight Energy Alter the System?
It returns carbon dioxide to the atmosphere that was absorbed millions of years ago.
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Describe How Nitrogen is Recycled in an Eco-System.
Nitrates are taken up by plant roots and converted to proteins. Animals eat the plants and excrete nitrogen as urea which is broken down to to nitrates again by bacteria. Bacteria also convert the protein in DOM to nitrates.
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Explain the Role of Micro-Organisms in an Eco-System.
Micro-Organisms use the wastes and organic matter as a substrate and release nutrients back to the soil.
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Explain the Role of Digestive Enzymes in an Eco-System.
Bacteria release digestive enzymes which break down DOM to mineral nutrients.
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Explain Why Some Plants Apparently Over Produce Pollen.
Pollen is released in huge numbers to try and make pollination occurs and the plant species reproduces successfully to survive.
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What is Meant by Deforestation?
The removal of forests to leave clear ground.
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Why Can Deforestation Lead to Drought and Flooding?
Foliage protects soil from erosion; the soil with plant roots growing in it can absorb water and prevent flooding. The water may release more slowly as it drains through soil. Forests help to recycle water by increasing evaporation from the ground.
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How does Deforestation Damage the Soil?
Loss of foliage exposes soil to erosion by heavy rain. The roots are lost and no longer bind together so it can be washed away.
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What Effect does this have on Rivers and Lakes?
Rivers and lakes become silted up as soil is damaged and washed away.
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What is an Eco-System Service? (Examples)
A life support system that we depend on four our survival. (the production of clean water from rainfall. The supply of oxygen from photosynthesis)
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What is Meant by Over-Exploitation?
Humans removing too much material from an eco-system making it unstable.
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Describe the Effect of Continuously Cropping the Same Food Plant from Soil.
The plant removes nutrients from the soil and the soil loses its fertility. Organic matter is not returned to the soil and the soil structure is damaged. Eventually the soil will dry out and erode.
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What Effects do Intensively Farmed Livestock Have on an Eco-System?
They remove nutrients from the soil by eating vegetation; they compact the soil preventing drainage, they trample plants and reduce biodiversity.
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How Does Intensive Agriculture Reduce Biodiversity?
Herbicides kill wees, and livestock trample plants. This limits the number of species of insects and other herbivores living in the eco-system.
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Why is it Important to Maintain Biodiversity on a Farm?
A range of plants on the farm will provide a wider range of habitats for insects and other animals. These may be pollinators or they may eat pests that damage the crops.
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Explain Why the Use of Crude Oil Does Not Fit in a Closed-Loop System.
The wastes (carbon dioxide, and other gases) are additional inputs to the system.
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What is a Quota?
A set amount of material (such as fish) that can be harvested.
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Explain Why Fishing Quotas are so Important?
To prevent over fishing which will deplete fish stocks and unbalance the eco-system.
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What is Meant by Restocking?
Breeding fish on a farm and realising them into the wild.
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Explain Why only Adult Fish Should be Caught?
They will have the opportunity to reproduce, ensuring the species survive
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Describe the Techniques Used to Prevent Deforestation.
Selective Felling (selecting certain types and sizes of trees), legislation to prevent clear felling.
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What are Nitrogen Fixing Bacteria?
Bacteria that live in the root nodules of legumes and take nitrogen out of the air to produce nitrates and proteins.
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How can the Action of Nitrogen-Fixing Bacteria be Maximised in Agriculture?
Growing legumes such as Clover or Beans in the fields and ploughing the dead plant roots back into the soil.
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Describe 2 Techniques Used in Agriculture to Overcome the Problem of Soil Erosion.
Adding natural manure or compost to the soil, avoiding ploughing too often.
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List 3 Ways we Use the Sun's Energy.
To grow plants and eat or burn the produce; convert the energy to electricity; use the energy to heat water in the solar panels.
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Describe How a Local Community Might Make Use of the Natural Eco-System Sustainable.
Take small amounts of produce, return all materials to the eco-system.
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Why Might Some Local Communities Start to Over-Exploit their Natural Eco-System?
The population gets too large and remove too many materials from the eco-system: they may produce too much waste for the eco-system to cope with.
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Explain Why Natural Eco-Systems Must be Conserved?
There may be unforeseen effects of losing an eco-system. It could destabilise another eco-system or impact upon our production of food.
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What is Bioaccumulation?
The concentration of a chemical (toxin) becomes more concentrated higher up the food chain. Starts in a plant becomes more concentrated higher up the food chain.
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Describe the Process of Eutrophication.
Extra nutrients in a water body cause algae growth. This blocks the light and kills the plants. Bacteria act to decompose the dead plants, using up all the oxygen and killing all the animals.
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What Process Uses Up Oxygen in Eutrophication?
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Card 2


What is Meant by a Closed-Loop System?


A system in which there is little input and the wastes from one process become the substrate for another process.

Card 3


Give an Example of a Closed-Loop System.


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Card 4


Which Type of System do Humans Often Create?


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Card 5


What is Meant by a Sustainable Process?


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