b7 - ecology

• abiotic factors - non-living factors
• abiotic factors include : Light intensity, temperature, humidity, soil pH, wind, salinity, carbon dioxide and oxygen levels etc.
• Different plants and animals are adapted to different habitats. If habitat conditions change rapidly, organisms may be unable to adapt to the changes and die
• competition promotes evolution and natural selection
• Competition- there is competition for food, resources, mates and space.
• Interdependence - different species depend on each other e.g. for food, shelter, or to spread seeds
• communities are stable when population size remains constant - this happens when organisms and environmental factors are balanced
• extremophiles are adapted to live in extreme environments
• organisms adapt to new conditions through evolution and natural selection
• adaptations can be structural, behavioural or functional
• biotic factors - living factors
• disease reduces population size by killing organisms
• In densely populated areas, disease can spread quickly so a large proportion of the population is killed.
• Predation - organisms which have lots of predators are more likely to be killed
• Biotic and abiotic factors interact in an ecosystem
• sampling methods (e.g. quadrats) show distribution and abundance of species
• biomass is produced by photosynthetic organisms (producers)
• food chains show direction of transfer of biomass
• materials cycle through biotic and abiotic components of the ecosystem
• material cycling : carbon cycle, water cycle
• microorganisms help return materials to the soil (minerals) and air (CO2) during decay
• land used up by growing infrastructure results in less space for other animal/plant habitats
• burning/decay of peat bog releases a large volume of CO2
• Habitats destroyed for resource harvesting: quarries, deforestation, peat bogs for compost
• large biodiversity leads to a more stable ecosystem
• biodiversity : Number of organisms and variety of species in an area, as well as the diversity of their genes
• large biodiversity leads to a more stable ecosystem
• maintaining biodiversity : habitat protection, breeding programmes, reintroduction of species, recycling waste, reduction of deforestation and replanting
• Growing population leads to more waste and a higher demand for raw materials
• Rising temperatures lead to extinction of species that cannot adapt e.g. coral reef
• global warming is caused by increased release of greenhouse gases, such as CO2 and methane
• global warming leads to more natural disasters
• deforestation leads to soil erosion, extinction, flash flooding and release of greenhouse gases
• deforestation : major cause of habitat destruction
• The final trophic level is made from apex predators which are carnivores with no predators e.g. humans
• The trophic level of an organism refers to its position in the food chain, food web or pyramid of biomass
• (trophic level) Level one - producers, photosynthetic organisms which use energy from light to produce biomass
• Level two - primary consumers, herbivores eat plants/algae
• Level three - secondary consumers, carnivores eat herbivores
• Level four - tertiary consumers, carnivores eat secondary consumers