Ecosystems

• What factors affect ecosystems

  .abiotic

  .biotic
• Wht is abiotic

  Non living entities e.g temperature or soil
• Wht is biotic

  Living organisms
• Give 3 examples of ecosystems

  .rock pools

  .playing field

  .large tree
• Describe biotic factors which affect rock pool

  .seaweed(producer)

  .herbivores eat this

  .so increases competition for seaweed(food)

  .so population can decline
• Describe abiotic factors affecting rock pool

  .high and low tides

  .affect PH,salinity,temperature

  .so organisms experience same factors as marine organisms

  .organisms which have wide range tolerance will survive
• describe abiotic factors affect in field

  .precipitation

  .water can log the soil

  .plants won’t grow

  .no food for consumers
• Biotic factors affecting large trees

  .leaves eaten by caterpillars

  .eventual death if tree
• Abiotic factors affecting tree

  .exposure to harsh environments e.g droughts

  .kill tree
• How is energy stored

  In biomass
• How is biomass transferred

  Through tropic levels
• How does transfer of biomass occur in ecosystems

  .food chains

  .food web
• Wht is food web

  Network of multiple food chains
• In which order does biomass transfer

  Producer to consumer
• Why is energy lost when transferred to next tropic levels

  .used in respiration

  .metabolic activities
• Wht is gross productivity

  Energy absorbed at a certain tropic level
• Wht is net productivity

  Energy will be lost from GP and so the actual energy available for next tropic levels is NP
• How do u work out NP

  GP-respiratory loss
• How to workout efficient energy transfer

  (NP/energy received )x100
• How to workout energy transfer

  .calculate biomass for each tropic level

  .biomass x size of population

  .this is total amount of energy in each tropic levels

  .difference in energy is energy transferred
• Why is energy transfer method not accurate

  .because one tropic level might not get energy from previous one

  .can get from various tropic levels due to food web
• List the 6 human activities

  .use of herbicides

  .use of insecticides

  .fungicides

  .natural predators

  .fertilisers

  .food for livestock
• Wht do the use if insecticides do

  .kill insects

  .prevents damage to crops

  .prevents biomass loss from crops
• How do herbicides ,fungicides ,insecticides benefit crops

  .larger size

  .increase productivity

  .faster growth

  .crops able to maximise full energy
• Give examples of wht goes to decomposers

  Roots,nails,bones
• Wht do decomposers do

  .take faeces of other organisms

  .clean environment

  .consume bacteria and fungi via saprotrophic mode
• Which cycles recycle nutrients

  .carbon cycle

  .nitrogen cycle

  .phosphorus cycle
• Why is nitrogen useful

  Its abundant in atmosphere ( a lot of it )
• 4 steps of nitrogen cycle

  .nitrogen fixation

  .ammonification

  .nitrification

  .denitrification
• Wht is nitrogen fixation

  .nitrogen gas turns into ammonia

  .by the bacteria Rhizobium

  .this bacteria is found in root nodules in legumes (peas)

  .ammonia turned into nitrogen compounds
• Describe ammonification

  .nitrogenous compounds from dead organisms converted into ammonia

  .by decomposers

  .then turned into ammonium ions
• Describe nitrification

  .converting ammonium ions in the soil to absorbable nitrate

  .ammonium ions to nitrite

  .then nitrite to nitrate
• Wht are saprobionts

  Decomposers
• Wht kingdom are saprobionts

  Fungi
• How to saprobionts digest

  .saprobiotic nutrition

  .secrete enzymes onto food or waste

  .extracellular digestion occurs

  .products externally absorbed by saprobionts
• Wht nutrients do saprobionts secrete

  .phosphate ions
• Why are saprobionts important

  .make nutrients in dead organisms available again

  .producers such as plants wouldn’t have enough nutrients

  .excrete important nutrient mineral ions
• Wht is symbiotic

  .mutually beneficial
• Wht is mycorrhizae

  .relationship between fungi and plant roots
• How does mycorrhizae occur

  .hyphae interact with roots

  .this increases surface area of roots

  .more mineral ions r absorbed

  .fungi receive glucose