ECOSYSTEMS Flashcards
Habitat
Place where organisms live
Population
All organisms of one species in a habitat
Producer
An organism that produces organic molecules using sunlight energy
Consumer
An organism that eats other organisms
Decomposer
An organism that breaks down dead or undigested organic material
Trophic level
Stage in food chain occupied by a particular group of organisms
Ecosystems
All the organisms living in a certain area and all the non-living conditions found there
Factors involved in an ecosystem
Biotic factors- living feature of an ecosystem
Abiotic factors- non living features of an ecosystem (temp, rainfall, shape of land and soil nutrient availability)
Biomass transfer
Main route of energy entrance is by photosynthesis, they store energy as biomass
Transferred when organisms eat eachother
Energy locked up in things that can’t be eaten eat recycled back into the ecosystem by decomposers
Food chains
Simple lines of energy transfer
Food web
Lots of food chains in an ecosystem and how they overlap
How is some energy lost
Light reflected from sunlight when it’s the wrong wavelength
Some parts of organism aren’t eaten
Some indigestible parts are passed through as faeces
Respiration and movement
Some stored as biomass
Net productivity
Amount of energy that’s available to the next trophic level
Gross productivity - respiratory loss
Human activities increasing energy transfer
Herbicides kill weeds which are competing with agricultural crops for energy
Fungicides kill fungal infections which damage agricultural crops
Insecticides kill insects that eat and damage crops
Natural predators eat pest species
Fertilisers are chemicals providing crops with minerals for growth
Rearing livestock intensively involves controlling the conditions they live in so more energy is used for growth and less for other activities (animals kept in warm places where movement is restricted and fed food higher in energy)
The carbon cycle
Carbon from air and water is absorbed by plants when they carry out photosynthesis- it becomes carbon compounds in plant tissues
Carbon passed on to primary consumers when they eat the plants
All living organisms die and the carbon compounds in the dead organisms are digested by microorganisms called decomposers
Carbon returned to the air by respiration
Organic matter can turn into fossil fuels over millions of years, the carbon in these fossil fuels are released when they’re burnt- combustion
Limestone and chalk composed of calcium carbonate
Carbon drawn down deep into earth crust by the movement of tectonic plates where they undergo chemical changes and release carbon dioxide which is returned by volcanoes
Rocks become weathered and combine with carbon containing compounds
Carbon dissolved into the sea and deep into the ocean by currents
The 4 steps of the nitrogen cycle
Nitrogen fixation
Anmonification
Nitrification
Denitrification
Nitrogen fixation
Nitrogen gas is released into the atmosphere and turned into ammonia by bacteria such as Rhizobium and Aztobacter
Ammonia then used by plants
Rhizobium are found inside root nodules in leguminous plants and form a mutualistic relationship with the plants providing them with nitrogen compounds and the plant provides them with carbohydrates
Aztobacter- found living in the soil and do not form mutualistic relationships with plants
Ammonification
Nitrogen compounds from dead organisms and animal waste are turned into ammonia by decomposers which goes on to form ammonium ions
Nitrification
Ammonium ions in the soil are changed into nitrogen compounds that can be used by plants
Nitrifying bacteria called Nitrosomonas change ammonium ions into nitrites
Other nitrifying bacteria called Nitrobacter change nitrites into nitrates
Denitrification
Nitrates in the soil are converted into nitrogen gas by denitrifying bacteria
They use nitrates in the soil to carry out respiration and produce nitrogen gas
Happens under anaerobic conditions
Succession
Process by which an ecosystem changes overtime
The biotic conditions change as the abiotic conditions change
Primary succession
Happens on land that has been newly formed or exposed, there is no soil or organic material to begin with
Species colonise a new land surface
Spores and seeds are blown in by the wind and plants begin to grow
The first species to colonise are called pioneer species
Abiotic conditions are hostile, only pioneer plants grown because they are specialised to cope and grow in harsh conditions (e.g marram grass)
Pioneer species change the abiotic conditions (when they die microorganisms decompose the dead organic material forming soil)
The conditions become less hostile so new organisms can grow
These new organisms die and decompose which adds more organic material making the soil deeper and richer in minerals
Larger plants like shrubs can start to grow which retains more water
As more plants move in, more habitats are made
Secondary succession
Happens at the same time but because there is already a soil layer, succession starts at a later stage
Pioneer species larger than in primary succession
Example of primary succession
Lichens grow on and break down rocks releasing minerals Lichens die and are decomposed helping to form a thin soil, this thickens as more organic material is formed which means species like mosses can grow Larger plants (flowering plants and grasses) that need more water move in as the soil deepens Shrubs, ferns and small trees begin to grow and outcompete the grasses and smaller plants to become the dominant species, diversity increases Soil is deep and rich enough in nutrients to support large trees, these become dominant species and the climax community is formed
Climax community
Ecosystem is supporting the most complex community of plants and animals it can, it’s won’t change much more and is at a steady state
Climax community in temperate climates
Contains large trees because they can grow in the conditions when soil has developed
Climax community in polar climate
Large trees will not be able to grow so the climax contains only herbs or shrubs
Plagioclimax
Deflected climax
When the succession is stopped artificially such as by humans activities
When succession is prevented by human activity but the plagioclimax that develops is different to any of the natural stages of an ecosystem
Investigating populations
Abundance- number of individuals of one species in a particular area
Distribution- where a particular species is in the area you are investigating
