Organism and its Environment PDF

**Organism and its environment** an organism: absorbs substances and energy from its environment builds its body and maintains its life processes it dies and is decomposed simple components are returned back to the nature this is the circulation of matter and flow of energy, organisms become speci...

**Organism and its environment** an organism: absorbs substances and energy from its environment builds its body and maintains its life processes it dies and is decomposed simple components are returned back to the nature this is the circulation of matter and flow of energy, organisms become specialised, they may die or even become extinct depending on their living conditions **Ecology** -scientific study of the relationships that living organisms have with each other/ their environment -the word was coined in 1866 by the German scientist Ernst Haeckel **Ecology, its levels and subdisciplines** 5 levels studied by ecology: an organism - it is an individual that can react to stimuli, reproduce, grow and maintain homeostasis a population -- it is a group of organisms of one species that live in the same place at the same time a community -- two or more populations of different species in the same area an ecosystem -- living organisms + non-living (abiotic) components the biosphere -- all of the ecosystems of the earth, all living things in the lithosphere, pedosphere, atmosphere and hydrosphere **Biotope ** -biotic and abiotic factors which surround a specific organism, population or community  **Sub-disciplines of ecology** autecology = the ecology of an organism demecology = the ecology of a population (its sturcture, relationships), synecology = the ecology of a community  **Abiotic Components of the** **Environment** **Light ** solar constant = 1.38 x 10³ J/s per m² energy of sun is transformed through photosynthesis into the energy of chemical bonds, solar radiation includes a whole spectrum of wavelengths visible spectrum is within wavelengths of 400 -700 nm, it is photosynthetically active radiation  properties of light: the quality of light in aquatic ecosystems blue and red light is absorbed by water, therefore some algae have additional pigments in order to use other colours light intensity it varies according to the latitude and the season of the year  the length of the day, it causes the phenomenon known as photoperiodism short-day plants flower if nights are long enough long-day plants flower if nights are short enough day-neutral plants they flower independently on the length of nights **Temperature** plants: many plants cannot survive the freezing and thawing processes influences of temperature: opening of flowers some plants require a cold period in order to blossom deciduous trees lose their leaves in winter  animals: ectothermic/endothermic species some animals hibernate in winter , some aestivate in summer there is seasonal migration in some animals  **Water** Plants: hydrophytes grow in water, require moist and muddy soils mesophytes have average water requirements xerophytes grow in dry environments -- not compulsory Animals: terrestrial animals are often exposed to dessication, adaptations: the chitinous body covering of insects the scales of reptiles.. few or no sweat glands tissues tolerant to water loss e.g. in camels the ability to absorb water in the form of water vapour  **Atmospheric gases ** oxygen -- needed for respiration carbon dioxide -- used during photosynthesis nitrogen -- present in proteins and nucleic acids, it is made available to plants by some bacteria and due to lightnings (wind, soil)