4) Ecology and the environment Flashcards
Population definition
A group of organisms of the same species living in the same place at the same time
Community definition
All of the populations living in the same area at the same time
Habitat definition
Where an organism lives
Ecosystem definition
All the biotic factors and all the abiotic factors that interact within an area at one time
Quadrat use
-square frames made of wood/ wire
-used to measure:
-number of an individual species
-species richness
-percentage cover
Investigate population size in 2 different areas
- Measure a survey area in your chosen habitat
- Use a random number generator to create a set of coordinates to place a quadrat
- Count the number of your chosen plant species that are found within this quadrat
- Estimate the population
Estimated population size = total area/ area sampled x total number of plants counted - Repeat with another area
Biodiversity definition
The range and variety of different species of organisms on Earth, or within an ecosystem
-considers species richness, variation, distribution, population size
Importance of biodiversity
-ensures stability of ecosystems by reducing the dependence of one species on another for food, shelter, maintenance of the physical environment
-populations are more likely to be resilient to sudden environmental impacts/ disease
Abiotic factors
-non living factor within an environment
-light, temperature, moisture levels, soil pH, wind intensity, carbon dioxide, oxygen level
Biotic factors
-living factors in an environment
-availability of food, predators, pathogens, competition
Trophic levels
-feeding relationships between organisms
-all energy is from the sun, transferred to environment as energy lost/ used at each stage
-non-cyclical, at top of food chain, lost to environment not recycled
Producers
Produce their own organic nutrients usually using energy from sunlight
Primary consumers
Feed on producers - herbivores
Secondary consumers
Predators that feed on primary consumers
Tertiary consumers
Predators that feed on secondary consumers
Quaternary consumers
Predators that feed on tertiary consumers
Food chain
Shows the transfer of energy from one organism/ trophic level of the food chain to the next
Food web
-A food web is a network of interconnected food chains
-more realistic - animals rarely exist on just one type of food source
-show interdependence
Pyramid of numbers
Shows how many organisms are at each level of a food chain.
-width of box = number
-generally, the larger an individual organism, the fewer of them there are
Pyramid of biomass
-shows dry mass of organisms at each level
-always pyramid-shaped
-mass of organisms decrease as you go up a food chain
Pyramid of energy
-show amount of energy contained in biomass of individuals within different trophic levels
-area = quantity of energy present
Losses of energy
Not all energy is transferred from one trophic level to the next
-only 10% of the energy of each trophic level is passed on to the next
-total amount of energy available eventually becomes too small to support another trophic level
Losses of energy due to
-don’t eat every part of animal
-not all ingested material is digested, absorbed
-energy is used for movement, generate heat, metabolic processes
-lost as waste - carbon dioxide, water, urea
The carbon cycle
-carbon taken out of the atmosphere in the form of carbon dioxide by plants used for photosynthesis
-passed on to animals and microorganisms by feeding
-returned to the atmosphere due to respiration
-when animals/ plants die, don’t decompose fully, carbon in their bodies can be converted over millions of years and pressure into fossil fuels
-fossil fuels are burned (combustion) - carbon combines with oxygen - CO2 released into the atmosphere
How nitrogen is taken out of the air/ converted into something easier to absorb
-nitrogen fixing bacteria in soil/ roots take nitrogen gas and change it into nitrates in the soil
-lightning can ‘fix’ nitrogen gas, split bonds between two atoms, turn them into nitrous oxides that dissolve in rainwater and leach into the soil
Nitrogen cycle
-Plants absorb nitrates in soil, use to make proteins
-Animals eat plants
-Waste from animals sends nitrogen back to soil as ammonium compounds
-Nitrifying bacteria convert ammonium compounds –> nitrites –> nitrates (nitrification) –> absorbed by plants
-denitrifying bacteria (found in poorly aerated soil) take nitrates out of soil, convert to nitrogen gas
Sulphur dioxide - pollution
-combustion of fossil fuels that contain sulphur impurities - creates sulphur dioxide and nitrogen oxides
-gases react with oxygen and dissolve in rainwater
-produce dilute sulphuric acid/ nitric acid
-acid rain
Acid rain
-can damage plants
-make rivers, lakes, too acidic
-results in the death of certain aquatic organisms
-cause the leaching of minerals that are toxic to fish, such as aluminium into lakes
Greenhouse gases
-gas that absorbs infrared radiation from the sun so it remains trapped in the Earth’s atmosphere
-water vapour
-carbon dioxide
-methane
-nitrous oxides
-CFCs
Carbon dioxide - pollution
-produced during the combustion of fossil fuels
-deforestation - trees cannot absorb CO2 from atmosphere
Methane - source
-from the decomposition of waste by microorganisms
-fermentation by microorganisms in the stomach of cattle
-fermentation by bacteria in rice fields
Greenhouse effect
-The Sun emits rays that enter the Earth’s atmosphere
-The heat bounces back from the Earth’s surface
-Some heat is reflected back out into space
-Some heat is absorbed by greenhouse gases and is trapped within the Earth’s atmosphere – this is normal
Consequences of enhanced greenhouse effect
-ocean temperatures increase - melting of ice caps
-increasing temperatures - cause extreme weather like superstorms, flooding, droughts
-change ecosystems
Effect of toxic chemicals (pesticides/ herbicides) - water pollution
-runoff into rivers
-chemicals cannot be broken down by organisms
-can be absorbed by aquatic plants/ invertebrates and build up in tissues of organisms over time - bioaccumulation
-at each stage of the food chain, level of chemicals increase
-eventually build up to toxic levels in predators - lead to death/ failure to breed - biomagnification
Untreated sewage - water pollution
-sewage provides a good source of food for bacteria which increase rapidly
-depletes oxygen dissolved in the water as they respire aerobically
-lack of oxygen results in the death of aqautic organisms such as fish
-eutrophication
Fertilisers - water pollution
-cause increased growth of algae, water plants
-results in algal bloom
-blocks sunlight so water plants on the bottom start to die
-algae also dies when competition for nutrients become too intense
-dead plants/ algae are a good source of food
-lead to eutrophication
-death of aquatic organisms
Effects of deforestation
-loss of biodiversity
-soil erosion
-flooding
-increased CO2 in the atmosphere
-disturbance of evapotranspiration
Deforestation - loss of biodiversity
-as rainforest habitat is destroyed
-causes the loss of large numbers of plants/ animals
Deforestation - soil erosion
-tree roots help stabilise the soil, prevents it from being eroded by the rain
-trees take up nutrients/ minerals from the soil through their roots
-without trees, nutrients and minerals will remain unused in the soil
-washed away into rivers and lakes by rain (leaching)
-loss of nutrients is permanent, makes it difficult for forest trees to regrow, even if land is not cultivated with crop plants/ grass for cattle
Deforestation - increased CO2 in the atmosphere
-trees carry out photosynthesis where they take in carbon dioxide, release oxygen
-removal of trees, less carbon dioxide is removed from the atmosphere, less oxygen released
-trees are often burned to clear for land, releases carbon dioxide
Deforestation - disturbance of the water cycle
-water released by trees by transpiration leads to the formation of clouds
-results in rainfall nearby
-if trees are cut down, local area may become drier due to less rainfall
