energy and ecosystems
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Energy and Ecosystems. Ecology. Habitat : Place where an organism lives Population: Group of the same species of organisms which live in the same place at the same time Community : All of the different species living in a habitat at the same time - PowerPoint PPT PresentationTRANSCRIPT
Energy and Ecosystems
EcologyHabitat : Place where an organism livesPopulation: Group of the same species of organisms
which live in the same place at the same timeCommunity: All of the different species living in a
habitat at the same timeEcosystem: A self contained system of organisms
interacting, which recieved energy as sunlight, and loses energy as heat. Nutrients are recycled within the ecosystem.
Niche: The place occupied by an organism in the food chain
Energy flow through ecosystems
Energy losses in food chains
Energy loss in ecosystemsNot all sunlight hits a photosynthesising
plantSome sunlight is reflected from leaf surfacesSome sunlight passes through the leaves and
is not converted to chemical energy.Some wavelengths of light cannot be used by
plants
Respiration – The building of ATP produces heat, which is lost to the surrounding environment
Food chains and food webs
Trophic levelsProducer : Photosynthesising organisms (plants)
produce all of the food for the ecosystem.1st order consumer: First animal consumer in the food
chain (herbivore)2nd order consumer Second animal in the food chain
(carnivore)3rd order consumer animals high in the trophic levels
often consume food from lower levels also (can be omnivores)
Detritis : Dead organismsDecomposer : Bacteria and fungi decay dead organismsDetrivores: Larger organisms which eat dead
organisms
ProductivityProductivity is the rate at which plants
convert sunlight to energy in an ecosystem.It is measured in kilojoules per m2 per yearGross productivity : Total energy convertedNet primary productivity: Remaining
chemical energy after plants have supplied their own needs for repiration.
Matter recycling : Nitrogen cycleNitrogen is essential for all living organisms
as a building block of proteins and nucleic acid
Most nitrogen is present in the atmosphere 78pc.
Nitrogen gas is unusable by most organisms, as the triple covalent bond in N2 molecules makes them too unreactive.
The most common useable form of nitrogen is in ammonia NH3 and nitrate NO3.
The conversion of nitrogen gas to useable nitrogen is called nitrogen fixation.
Nitrogen FixationNaturalLightning in atmosphere creates nitrogen oxide gasses
by reacting oxygen with Nitrogen. These gasses fall to the soil in rain. Tropical ecosystems obtain a very large amount of useable nitrogen this way.
Nirogen fixing bacteria ie Rhizobium use an enzyme called nitrogenase. This catalayses nitrogen to ammonia.
Rhizobium can live in soil and in the roots of legumous plants. Legumous plants have root nodules which the bacteria can live in, and get supplied with atp
Nitrogen Cycle
SyntheticHaber proccess : This is the synthetic
proccess used to make ammonia for fertilisers. It uses very large ammounts of electrical energy, and has made it possible for farmers to produce march larger crop yields.
use of nitrogenNitrate ions are obtained from the soil by
plants in their xylemAnimals obtain nitrogen by digesting plants,
or other animals. Digestion breaks proteins into amino acids ready to use by the animal
Denitrification bacteria can reverse nitrogen fixation in their metabolic proccesses. They are common in sewage treatment plants and compost heaps.