# Energy and Ecosystems

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• Created by: trudyyyyy
• Created on: 03-01-19 13:59
Explain what a saprobiont is.
An organism that breaks down complex molecules in dead organsims, into simple molecules. Often release valuable nutrients into the soil to be reused.
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What is Biomass?
The total mass of living material in a specific area at a give time. Often times dry mass is more useful than fresh mass as varying amounts of water can make any comparisons unreliable.
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Unit of Biomass?
Mass in given area in given time E.g grams per metre squared.
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How is a calorimeter used to estimate the chemical energy stored in biomass?
A dry sample is weighed and burnt in oxygen in the bomb of the calorimeter. The bomb is surrounded by a known volume of water of which the temperature changes slightly when the sample is burnt. We can use this information to calculate the KJkg-1.
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What is the equation used to determine chemical energy?
J=mc^T
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What is the equation for net primary production?
net primary production= gross primary production - respiration.
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Why do plants only absorb about 1-3% of the Suns energy that is available to them?
Over 90% is reflected back into space by clouds and the atmosphere. The pigment in plants can only absorb certain wavelengths of light, the rest are reflected. Light may not fall on chlorophyll molecule. Limiting factors may reduce photosynthesis.
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Why is a low percentage of energy transferred at each trophic level?
Some of the organism is not consumed. Some parts cannot be digested so pass through into faeces. Some energy lost into urine. Lost due to respiration.
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Why do most food chains only contain four or five trophic levels?
Due to inefficient energy transfer at each level, there is not enough energy available to support a large enough breeding population at higher trophic levels.
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How does intensive farming increase the efficiency of energy transfers?
Movement is restricted so less respiration needed to facilitate this. Warm environment so animals don't need to use energy to maintain body temp. Controlled feeding so animals can have optimum growth. No predators.
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What are the problems associated with mono cultures?
They cause insects and fungal pests to spread rapidly. Reduces biodiversity. Less plants and hedges will cause a reduction in bird life due to loss of food source and habitat.
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The key components of the nutrients cycle.
Producers, Consumers and Saprobionts.
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What are the four main stages of the Nitrogen cycle?
Ammonification, nitrification, nitrogen fixation and denitrification.
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What is nitrogen fixation?
Nitrogen gas in the atmosphere is converted into nitrogen containing compounds. This is normally facilitated by nitrogen fixing bacteria which can be found in leguminous plants such as clover.
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Where is the most prominant natural source of phosphate ions.
In sedimentary rock deposits.
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Beginning with the phosphate ions found in rocks, outline the potential cycle of inorganic phosphate.
Phosphates in the rocks are released into water sources or in soil by the erosion of rocks. Dissolved phosphates in water and soil are taken up by plants. Plants are consumed by animals, passing on the phosphate. Animal excretion and decomposition.
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Describe the role of mycorrhizae.
This is the relationship between plant roots and fungi. It is mutually beneficial as the surface area for exchange in the roots is increased so more nutrients can be absorbed from the soil. Also, the fungi receives organic compounds from the plant.
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Explain the effect of fertilisers on local water sources.
Leaching occurs and fertilisers run into water sources. This causes an increase in algae population. When plants and algae die, lots of decomposers are needed to break them down. The use up lots of oxygen causing a BOD.
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## Other cards in this set

### Card 2

What is Biomass?

#### Back

The total mass of living material in a specific area at a give time. Often times dry mass is more useful than fresh mass as varying amounts of water can make any comparisons unreliable.

Unit of Biomass?

### Card 4

#### Front

How is a calorimeter used to estimate the chemical energy stored in biomass?

### Card 5

#### Front

What is the equation used to determine chemical energy?