ecosystem

what is an ecosystem?

• all living organisms that interact with one another in a defined area and also the physical factors present in that region

explain temperature as an abiotic factor

• each species have their own optimum temperature

• further from optium, fewer can survive

• ectothermic animals grow faster when in a warmer temperature (they don’t control their own temperature)

• changes in temperature over seasons can trigger migration or lead fall

what is the affect of greater light intensity?

• greater rate of photosynthesis

• mores seeds

• increased population

• more animals can be supported

why is it beneficial for aquatic ecosystems to have fast flowing water?

• as it has high concentrations of oxygen

what is the problem with water logged soil?

• less oxygen for plants

why is soil important?

• provides minerals needed for growth

• water (for photosynthesis)

• anchorage for roots

what are 3 main soil types?

• clay

• loam

• sandy

what are features of clay?

• fine particles

• easily waterlogged

what are features of loam?

• soil that contains mixture of sand and clay

• can retain water without being waterlogged

what are features of sandy?

• large particles

• well separated to allow draining

• does not retain water

what are some adaptations to abiotic factors?

• webbed feet so can walk on land and swim in water

• thick blubber to keep warm in cold seas where food is plentiful

• hibernate in winter to increase chance of survival as conserve energy in coldest months

what are adaptations to biotic factors?

• twigs used to fish for termites, another source of food

• dancing before mating, ensuring they are of the same species

• some bacteria produce antibiotics which kills other species of bacteria

what are tropic levels?

• positions or stage that something occupies in a food chain

why do food chains rarely go beyond a quaternary consumer?

• not sufficient biomass and energy left to support other organisms

• as energy is used and lost along the food chain

what are ways biomass is lost?

• used to provide energy for growth etc

• lost in urine and faeces

• energy from cellular respiration is transferred by heating the surroundings

what is biomass?

• mass of living material present in a particular place or in particular organisms

• so like energy content

how do you work out biomass?

• biomass in each organism x number of organisms in that tropic level

what are 2 ways of measuring biomass?

• mass of fresh material present (easiest method but unreliable as amss of water varies greatly)

• dry mass (most accurate but organisms have to be killed and put in an oven at 80 degrees to evaporate all the water

what are the units for areas of land?

• gm^-2

what are the units for areas of water?

• gm^-3

what is ecological efficiency?

• efficiency with which biomass or energy is transferred from one tropic level to the next

• there is less biomass in the next tropic level along

what is the energy available at each tropic level units?

• KJm^-2 yr^-1

how do you work out ecological efficiency?

• energy of biomass after transfer/ energy of biomass before transfer x 100

what is efficiency of producers?

• producers convert 1-3% of light energy,therefore biomass

• 90% of solar energy is reflected, some transmitted, some unusable wavelength

• limiting factors of photosynthesis is water availability and some unusable wavelength

• some energy lost photosynthetic reactions

what is net production in producers equation