Chapter 13 biology: Energy and ecosystems

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What is biomass?
The total mass of living materal in a specific area in a given time
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Organisms can be divided into 3 groups, what are these 3 groups?
1. Sapriobionts 2. Producers 3. Consumers
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What are producers?
Photosynthetic organisms that manufacture organic substances using light energy, water, carbon dioxide and mineral ions
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What are consumers?
Organisms that obtain their energy by feeding on other organisms.
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What are the 3 types of consumers?
Primary consumer - eat on producers Secondary consumers - eat on primary consumers Tertiary cosumers - eat secondary consumers
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What are saprobionts?
(DECOMPOSERS) a group of organisms that break down complex materials in dead organisms into simple ones.
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Why are saprobionts good?
Because when they decompose complex material they release valuable minerals and elements in a form that can be absorbed by plants
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What is a food chain?
A feeding relationship
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What is a trophic level?
Each stage of a food chain
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What do the arrows in a food chain represent?
Energy flow
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What are food webs?
How food chains are linked together within a single habitat
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What is fresh mass?
Living material including the water it obtains
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What is the problem and positive of fresh mass?
It is quite easy to asses but the prescense of varying amounts of water makes it unreliable
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What is dry mass?
Living material excluding water it obtained
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What is the positive and problem of dry mass?
The organisms must be dead and it is used on only a small sample which may nnot be presentative but the data is more reliableas you dont have the factor of water.
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Is biomass more often measured using dry mass or fresh mass?
Dry mass per given area in given time
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What is biomass measured in? (on land)
grams per square metre
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What is biomass measured in? (in water)
grams per cubic metre
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How is the method to measure the chemical energy in dry mass?
Calorimetry
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What happens during bomb calroimetry?
A sample of dry material is weighed and is then burnt in pure oxygen within a sealed chamber called a bomb. The bomb is surronded by a water bath and the heat of combustion causes a small temperature rise in this water.
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What is a habitat?
The place where an organism normally lives and which is characterised by physical conditions and the types of other organisms present
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What is an ecosystem?
All the living and non-living components of a particular area
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How is most of the suns energy not converted to prganic matter by photosynthesis?
1. Reflected back by clouds 2. not all wavelenghts of light can be absorbed and used 3. light may not fall on a chlorophyll molecules 4. another limiting factor such as low CO2 may limit rate of photosynthesis
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What is gross primary production?
The total quantitiy of chemical energy store in plant biomass, in a given area/volume
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What is net primary productivity?
The chemical energy store which is left when chemical losses to respiration have been taken into account
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what is the equation for working out net primary production?
NPP = gross primary production - respiratory losses
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Why is it that sometimes there is a low percentage of energy transffered from each stage of a food chain?
1. Some of the organism is not consumed 2. Some things cannot be digested so lost in faeces 3. Some of the energy is lost in excretion 4. Enegy losses occur as heat from respiration and lost to the envrionment
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Why are energy losses high, due to heat, much higher in mammals?
Because they have to maintain body temp which requires more energy
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How is net production of consumers calculated?
N = I - ( F + R ) (N: Net production, I: chemical energy store of ingested food, F: energy lost in faeces and urine, R: energy lost in repiration)
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What is the simple sequence of all nutrient cycles? (part 1)
1. The nutrient is taken up by producers as simple inorganic molecules 2. The producer incorporates the nutrient into complex organic molecules 3. When the producer is eaten, the nutrient passes into consumers
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what is the simple sequence of all nutrient cycles? (part 2)
4. It then passes along the food chain when these animals are eaten by other consumers 5. When the producers and consumers die their complex molecules are broken down by saprobiontic microorganims that release the nutrient in its original simple for.
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What are the two types of fertilisers?
Natural (organic) - dead decaying remians and animal wastes 2. Artificial (inorganic) - mined from rocks and converted into different forms
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How does nitrogen increase productivity?
It is an essential component of amino acids, nucleotides in DNA and ATP. Plants will grow talller and have greater leaf area which increases the rate of photosynthesis and improves crop productivity
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How can nitrogen-containing fertilisers have detrimental effects?
1. Reduced species diversity (because they favour growth of rapidly growing species 2. Leaching 3. Eutrophication
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What is leaching?
The process by which nutrients are removed from the soil. Rainwater dissolves soluble nutrients and carry them deep into the soil eventually into watercourses which can be harmful to organisms and drinking water.
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What is eutrophication and what are the stages of eutrophicationation? (part 1)
The process by which nutrient concentrations increase in bodies of water. 1. In most lakes and rivers there is naturally very low concentration of nitrate and so notrate ions are a limiting factor for plant growth
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What is eutrophication and what are the stages of eutrophicationation? (part 2)
2. Nitrate ion concentration increases as a result of leaching, it ceases to be a limiting factor for growth of plants 3. As algae mostly grow at the surface, the upper layers of water become densely populated with algae 'algal bloom'
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What is eutrophication and what are the stages of eutrophicationation? (part 3)
4. This dense surface layer of algae absorbs light and prevenrts it from penetrating to lower depths 5. Light then becomes the limiting factor for growth of plants so they eventually die
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What is eutrophication and what are the stages of eutrophicationation? (part 4)
6. The lack of dead plants is no longer a limiting factor for the growth of saprobiontic bacteria and so these populatins grow 7. Saprobiontic bacteria require oxygen for respiration which causes an increased demand
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What is eutrophication and what are the stages of eutrophicationation? (part 5)
8. The concentratin of oxygen in the water is reduced and nitrates are released from decaying organisms 9. Oxygen then becomes the limiting factor for the population of aerobic organisms. These organisms ulitmately die as oxgen is used up altogether
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What is eutrophication and what are the stages of eutrophicationation? (part 6)
10. Withot aerobic organisms, there is less competition for anaerobic organisms whose populatins now rise 11. The anaeroic organisms further decompose dead material releasing more nitrates and some toxic wastes which make water putrid
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Organisms can be divided into 3 groups, what are these 3 groups?

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1. Sapriobionts 2. Producers 3. Consumers

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What are producers?

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What are consumers?

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What are the 3 types of consumers?

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