organisms and their environment Flashcards
explain energy flow/non-cyclical flow
-in an ecosystem, energy enters in the form of light energy from the sun
-light energy is absorbed by chlorophyl in producers and converted in CPE during photosynthesis
-energy is passed on from one trophic level to the next by feeding. however, approximately 90% of energy is lost and only 10% is passed on
-caused by: respiration as energy is lost in the form of heat, through egested materials, uneaten plants, dead organism, bulk of energy trapped in these organisms lost as heat
-heat does not return to the same system, thus non-cyclical
describe nutrients flow/cyclical flow
-in an ecosystem, energy enters in the form of light energy from the sun
-light energy is absorbed by chlorophyl in producers and converted in CPE during photosynthesis
-energy is passed on from one trophic level to the next by feeding.
-during respiration, CO2 produced which can be used back by plants for photosynthesis
-egested and excreted materials, and dead organisms contain trapped chemical energy
-this energy is released through decomposers. they would use these trapped energy for their needs while carrying out respiration as well (CO2!)
why do food chains usually have less than 5 trophic level
-90% of energy is lost when passing from one level to the other [to env during respiration, to uneaten body parts, faeces, excretory products]
-energy would be insufficient to support a long food chain
decomposers
organisms that get their energy by breaking down dead organisms, faeces and excretory products
-their activities return nutrients to the environment. eg mineral salts
-eg of decomposers: bacteria, fungi
reasons for using pyramid of numbers
-compare the number of organisms present in each trophic level at a particular time
-does not need to kill animals [unlike biomass]
limitations of pyramid of number
-does not consider size and mass of organism
-does not consider whether the organism is an adult or a juvenile
reasons for using pyramid of biomass
-considers size and mass of organism, thus more accurate representation [unlike pyramid of no]
limitations of pyramid of biomass
-organisms have to be killed to obtain biomass
-has to be constructed at a particular point in time
carbon cycle
-regulates amount of CO2 in atmosphere to ensure the continuous supply of CO2 for plants to carry out photosynthesis
-glucose, a store of chemical energy, is produced. this enables energy to flow through the ecosystem in the form of carbon compounds during feeding, supporting survival and growth of organisms
-5 processes: photosynthesis, feeding, respiration, decomposition, formation of fossil fuels and combustion
carbon sink
-area that stores carbon from the atmosphere for a long period of time
-stores more carbon than it releases
-egs. ocean, forest
how does sewage/fertiliser/eutrophication affect the environment
-untreated sewage/fertilisers that are not absorbed by crops may be washed by rainwater into nearby lakes or oceans
-nitrates and phosphates in untreated sewage/fertilisers enhance the growth of algae and water plants
-increase growth and multiplication of algae and floating water plants [eutrophication]
-overcrowding of algae and water plants prevents sunlight from reaching submerged plants
-submerged algae and plants die due to lack of sunlight
-decomposed by aerobic bacteria and fungi
-as bacteria feed on decaying organic matter, they grow and multiply rapidly, using up the oxygen in the water
-fish die due to lack of oxygen
how does insecticides affect the environment
-insecticides [eg DDT] are insoluble in water and cannot be excreted which is thus stored in the fatty tissues of organisms
-other organisms will feed on the organisms in the lower trophic level, causing and increase in concentration of DDT, also known as bioaccumulation
-when these DDT are passed from one trophic level to another, it results in bioamplification/biomagnification
-leads to death/population decrease
reasons for conservation
-maintaining biodiversity, prevent extinction
-scientific research
-economic purposes
-maintain stable and balanced ecosystem
-preserve natural scenery and wildlife for people to appreciate
