Ecology

    Cards (30)

    • Ecosystem: interaction of a community of living organisms and non-living parts of their environment
      Population: all the organism of one species living in a habitat
      Interdependence: how organisms in a community depend on other organisms for vital services
    • Abiotic factors
      light intensity and temperature
      o both affect the rate of photosynthesis (limiting factors) which affects the rate of plant growth
      o plants are good food sources and shelter for many organisms
      • soil pH and mineral content
      o soil pH affects the rate of decay and therefore how fast mineral ions return to the soil to be taken up by other plants
      o different species of plants thrive in different nutrient concentration levels
      o low mineral concentrations could cause nutrient deficiencies reducing plant growth and reducing pop.
    • Abiotic factors:
      wind intensity and direction
      o wind affects the rate of transpiration in plants
      o increased transpiration increases the rate of photosynthesis
      carbon dioxide levels (for plants)
      o CO2 affects the rate of photosynthesis (see light intensity and temp.)
      o it also affects the distribution of organism as some thrive in high CO2 environments
    • Abiotic factors:
      oxygen levels (for aquatic animals)
      o levels in water vary massively (unlike in the air)
      o most fish need high concentrations of oxygen to survive
      moisture levels – plants and animals require water to survive
    • Biotic factors
      • food availability – more food allows for more successful breeding so population size increases
      • new predator arriving – decreases the population of prey
      • new pathogen – the population has no resistance to it so they can be quickly wiped out
      competition with a new species – if one species is better adapted to the environment, it will breed more successfully until the lesser adapted species has too small a population to breed successfully
    • o Structural – shape or colour of an organism
      ▪ sharp teeth of carnivores to tear meat apart
      camouflage e.g. white fur in artic regions to avoid being spotted by predators/prey
      thick layer of fat in cold environments for insulation
      low surface area to volume ratio to retain heat in cold environments
    • o Behavioural – the way an organism behaves
      ▪ playing dead to avoid predators
      basking in the sun to avoid heat
      ▪ migrating to warmer climates during winter to avoid cold environments
    • o Functional – the processes that occur in an organism e.g. reproduction and metabolism
      ▪ conservation of water through producing little sweat and small amounts of concentrated urine
      ▪ hibernation in winter (lowering metabolic rate to conserve energy)
    • Extremophiles: Organisms that live in extreme environments e.g. extremely high temperatures, pressures or salt concentrations e.g. example, bacteria which live deep in sea vents where pressure is extremely high
    • o all food chains begin with a producer which synthesises molecules
      glucose produced is used to synthesis other biological molecules in the plant – the biomass
      o producers are eaten by primary consumers
      energy is transferred through organisms in an ecosystem when one is eaten by another
      o primary consumers are eaten by secondary consumers
      ▪ the animals eaten are called prey and the consumers that kill them are called predators
      o secondary consumers are eaten by tertiary consumers
    • • Distribution: where an organism is found
      • Abundance: the population size of an organism
      • Quadrat: 1m x 1m square frame enclosing an area of 1m2
    • • Water cycle
      o solar radiation causes evaporation in bodies of water, transpiration in plants also forms water vapour
      o water vapour rises and condenses forming clouds
      o water is returned to the land as precipitation which runs into bodies of water or infiltrates into the group
      o the cycle repeats providing fresh water for plants and animals on land before draining into the seas
    • • Carbon cycle
      o CO2 is REMOVED from the atmosphere in photosynthesis by green plants and algae – they use carbon to create carbohydrates, proteins and fats (carbon compounds). Plants are eaten moving carbon up the food chain
      o CO2 is RETURNED to the air when plants, algae and animals respire, decomposers (microorganisms that break down dead
      organisms and waste) respire while returning mineral ions to the soil
      o CO2 is RETURNED to the air when wood and fossil fuels are burnt (combustion) as they contain carbon
    • Decomposition
      o Temperature – increasing temperatures increases the rate of decomposition as they increase the rate at which enzymes involved in decomposition work. If too hot/cold the enzymes denature stopping decay
      o Water – decay takes place faster in moist environments because decomposers need water for respiration (producing energy for movement, decomposition and growth)
      o Availability of oxygen – decomposers need oxygen to respire (produce energy)
      o Number of decomposers – the more decomposers and detritus feeders there are the faster the decay
      occurs
    • Anaerobic decay by decomposers (to decompose organic matter) produces methane gas
      o biogas (made of mainly methane) is made in a simple fermenter called a biogas generator
      o biogas generators need to be kept at 30°C to keep the decomposers respiring
      o the biogas produced can’t be stored as a liquid (needs too high of a pressure) so it has to be used straight away e.g. burnt for heating, cooking or to power a turbine to generate electricity
    • o there are 2 forms of biogas generator
      batch generators – manually loaded with waste which is left to digest, and the by-products are cleared away at the end of each session (produces biogas in small batches)
      continuous generators – make biogas all the time as waste is continuously fed in and the biogas is produced at a steady rate (more suited to large scale biogas production)
    • • environmental changes affect distribution of species in ecosystem
      o Temperature – increasing temperatures leads to migration of species
      o Availability of water – during wet and dry seasons the amount of rainfall will change, populations migrate to find water
      o Composition of atmospheric gasesair pollution can affect which species can be present
    • • a high biodiversity ensures the stability of an ecosystem by reducing the dependence of one species on another for food, shelter and the maintenance of the physical environment
    • Peat bogs
      • peat forms when plant material has not fully decayed due to lack of oxygen, this accumulates in bogs which are acidic and waterlogged
      • the destruction of peat bogs (and other areas of peat to produce garden compost)
      o reduces the size of this habitat reducing the biodiversity
      o the decay and burning of peat releases carbon dioxide into the atmosphere
      • they are being destroyed faster than it is being formed (as formation is slow)
    • • effects of deforestation
      o release of CO2 – trees contain carbon which is oxidised during combustion to release CO2 (contributes to global warming) also microorganisms decompose dead vegetation producing CO2 as they respire
      o reduction in absorption of CO2 – less trees means less photosynthesis
      o decreased biodiversity – trees act as habitats for a huge range of species
    • o breading programmes for endangered species – avoids extinction
      o protection and regeneration of rare habitats – e.g. mangroves and coral reefs (protects the species that live there preserving the ecosystem)
      o reintroduction of hedgerows and field margins – especially if only 1 crop grown on the field it increases biodiversity by providing a habitat for many species
    • Trophic levels:
      o Level 1 – producers (plants and algae that produce their own food by photosynthesis - autotrophs)
      o Level 2 – primary consumers (herbivores that eat plants/algae)
      o Level 3 – secondary consumers (carnivores that eat herbivores)
      o Level 4 – tertiary consumers (carnivores that eat other carnivores)
    • • biomass is lost due because...
      o not all ingested material is absorbed (some is egested as faeces)
      ▪ animals do not have all the enzymes to digest all the material they eat
      o some absorbed material is lost as waste e.g. carbon dioxide and water in respiration and urea in urine
      o large amounts of glucose are used during respiration
      o not all biomass can be eaten e.g. carnivores don’t generally eat bone or teeth
    • efficiency of biomass transfer = biomass transferred to the next level ÷ biomass available at previous level
    • Biological factors threatening food security
      o increasing birth rate
      o changing diets in developed countries means scarce food resources are transported around the world
      o new pests and pathogens that affect farming
      o environmental changes affecting food production e.g. lack of rain causing draughts
      o cost of farming e.g. seeds and machinery
      o conflict affects the availability of food and water
    • • the efficiency of food production can be improved by restricting energy transfers from food animals to the environment by...
      o limiting their movement (small pens or cages)
      o controlling the temperature of the surroundings (less energy to control own body temperature)
      o feeding animals high protein foods to increase growth
    • mycoprotein – protein-rich food source suitable for vegetarians made from the fungus Fusarium
      o the fungus is grown in glucose syrup
      o air and ammonia are added so the conditions are aerobic, and the protein can be made using the nitrates
      o the fungal biomass is harvested and purified
      o ADVANTAGES OVER ANIMAL PROTEIN - reduces land use as animals take up a lot of land and reduces methane production (as livestock’s digestive systems produce lots of the greenhouse gas)
    • • genetically modified bacteria
      o a plasmid is removed from a bacteria using lysozyme
      o the insulin producing gene is removed from a human chromosome using restriction enzyme
      o the plasmid is cut open using the same restriction enzyme – leaving the same sticky end
      o the plasmid and human gene are joined using ligase enzyme which joins the sticky ends producing recombinant DNA
      o the recombinant DNA is inserted into a bacterium
      o the transgenic bacterium is grown in a vat, millions of identical bacterium are collected which all produce human insulin – the insulin is
      harvested and purified
    • o Advantages
      ▪ GM crops can be resistant to pests and extreme weather (e.g. draughts) improving yields
      ▪ some crops are modified to have more nutritional value e.g. Golden Rice contains beta-carotene which is high in vitamin A (helps to prevent blindless)
    • o Disadvantages
      ▪ there are fears that some countries may become dependent on countries producing GM seeds
      ▪ sometimes poor soil is the reason crops fail so even GM crops wouldn’t survive
      ▪ GM crops are aften more expensive so won’t help combat food insecurity
      ▪ there are concerns over their impacts on health e.g. they may cause allergies
      ▪ concerns that if the genes reach weeds “super weeds” could be produced which are herbicide resistant
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