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Biology Unit 4.1, Biology Unit 4.3, Biology Unit 4.2, Biology Unit 4.4 -…
Biology Unit 4.1
Autotrophs
- Organisms who can form nutritional organic substances from inorganic molecules (photo and chemo synthesis)
Chemoautotrophs
- Produce organic molecules from chemical energy
Photoautotrophs
- Produce organic molecules from light energy
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Species
- A group of genetically similar organisms which can interbreed and produce fertile offspring
- Members of the same species have a common gene pool
Species can become reproductively isolated because of
- Geographical barriers
- Behavioural differences
- Niche partitioning
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Heterotrophs
- Organisms who gain their organic compounds by consuming other organisms
Consumers
- Organisms who are not capable of synthesising their own food and must gain it by consuming other organisms through ingestion or absorption
- Take the energy rich carbon compounds such as sugar, proteins, lipids
Detritivores
- Organisms that gain their nutrients via feeding off dead organic matter
Saprotrophs
- Obtain energy from detritus through external digestion by excreting enzymes to break down the debris around them
Primary, secondary and tertiary consumers
Communities
Mutualism
- Both organisms benefit
Commensalism
- One organism benefits and other unaffected
Parasitism
- One benefits and the other affected
Predator-prey
- One organism hunts and feeds on another
Nutrient Cycling
- The continuous flow and reuse of nutrients and other chemicals in and out of stores in an ecosystem
- The movement of organic molecules and minerals through the food chain and back into the soil so that it can be reabsorbed by plants and reenter the food chain
Decomposers convert the organic molecules in detritus in order for it to be used for themselves and other animals
Biology Unit 4.3
Carbon cycle
Carbon can be taken out of the atmosphere by plants and stored or used to make oxygen and carbohydrates
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Accumulation of shells goes through the process of lithification, creating a large carbon sink
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Some animals eat other organisms and excrete, taking out and once again releasing carbon
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Methane
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Peat formation
Peat forms when organic matter is not fully decomposed because of anaerobic conditions in waterlogged soils
- Very acidic = decomposers cannot live and more peat accumulates
Carbon dioxide in water
When carbon dioxide diffuses into water, it creates bicarbonate ions and H+ ions
-H+ ions change the pH of water, making it more acidic
Fossil fuels (oil, gas and coal)
Remains of dead plants and animals compiled in anoxic conditions exposed to heat and pressure within the earth's crust over hundreds of millions of years, eventually converted into oil, natural gas, or coal
Role of autotrophs in carbon cycle
Autotrophs take carbon out of the atmosphere and convert it to carbohydrates and oxygen
Biology Unit 4.2
Food chains, webs and loss of energy between trophic levels
Food chain: A sequence showing the feeding relationships and energy flow between species
Food web: Shows the interconnecting relationships that exist amongst food chains
Energy transfer per trophic level is estimated to be around 10-20% due to
- Loss of heat due to respiration
- Loss of nutrients due to excretion
- Loss of nutrients due to not eating the entire of an animal
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Pyramids of energy
- Show the number of energy available per trophic level
- cannot have a larger second layer than first layer as there has to be sufficient energy to sustain larger animals
- Kj m-2 y-1
Pyramids of numbers
- Show the population numbers in each trophic level
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