the living world

• what is an ecosystem

  a system that contains biotic and abiotic organisms and the environment in which they live
• what are producers

  found at the bottom of the food chain or ecosystem and normally photosynthesise to create energy
• what are consumers


  an organism that get its energy from producers/ other consumers
• what are decomposers


  break down dead and decaying matter
• what is nutrient cycling?

  • Through decomposition, nutrients are put back into the soil.
  • Plants take up these nutrients as food. These plants may go on to be eaten by consumers.
  • When plants or consumers die, the nutrients are returned to the soil.
• what are trophic levels

  levels at which energy form the sun is held in plants/animals

  
• what is a biome

  a large-scale ecosystem that covers countries/continents

  e.g biome of Africa

  
• features of a tundra

  high latitudes(close to poles)

  dry and windy

  cold winter and brief summers

  shrubs slow growing and low lying due to low temp; low biodiversity

  
• features of a tropical rainforest

  lies on/near the equator

  hot and humid all year

  lots of clouds; heavy rainfall all year round

  lots of dense vegetation; biodiverse

  
• features of grassland

  between tropics

  dry &rainy seasons

  no trees just grasses
• features of a hot desert

  just north/south of equator

  hot with little rainfall (<250mm)

  high pressure so clouds hardly form; cold at night

  cacti and basic shrubs grow there

  
• features of a deciduous forest

  mid latitudes

  four seasons

  temperate climate

  low pressure and high rainfall; biodiverse

  trees lose leaves in winter to retain moisture and energy

  
• features of polar areas

  north/south poles

  very cold; icy and dry

  high pressure so no clouds

  inhospitable- not much grows at all; little plant/animal variation

  
• what two nutrients inputs involved in nutrient cycling

  -weathered rocks: release chemicals into soil

  -rainwater: washes chemicals out of atmosphere into ground

  
• what is biomass


  total mass of an organism
• what is litter in nutrient cycling

  when plants die or drop organic matter e.g loose decaying leaves

  
• what is a food chain

  -a diagram that shows link between producers and consumers

  -uses arrows to indicate transfer of nutrients/energy
• what is a food web

  -connects multiple food chains

  -shows connection between multiple consumers/producers in an ecosystem
• how much is passed up from one trophic level to the next?

  10%

  
• what are a few reasons why biomass is lost at each level in the food chain

  1)excretion

  2)respiration

  3)when parts of an organism aren't eaten e.g bones/ a plant's roots
• what are two different ways that an ecosystem can change

  globally e.g climate change

  locally e.g hunting animals
• what are examples of natural changes to ecosystems

  1)extreme weather events e.g drought, flooding

  2)fire from natural cuases e.g lightning

  3)natural spread of invasive species

  4)long term climatic changes
• what are examples of human changes to ecosystems

  1)land use change e.g deforestation

  2)water extraction

  3)hunting animals

  4)introduction of invasive species
• which factors put freshwater pond ecosystems at risk?

  1)water extraction- pond may dry out and not enough to support producers which will impact food web

  2)fish stocking- when fishes are introduced to ponds for fishing but are often tertiary consumers so if numbers are too high it can impact food web

  3)pollution- pesticides/ fertilisers carried into ponds by runoff. Fertilisers cause algae to grow rapidly (algal bloom) and they take a lot of o2, reducing o2 for other organisms

  4)drought- rivers and ponds dry up, vegetation may die due to lack of water
• what are biomes


  large scale ecosystems
• what two main factors impact biomes

  global circulation- warm air rises, clouds form =low pressure; air is sinking, difficult to form clouds= high pressure

  insolation- concentration of the sun's energy, depends on latitudes
• what are the 4 main layers of tropical rainforests

  1)emergents- tallest trees; 40-50m;rise above canopy

  2)canopy- thickest foliage; half of wildlife live here e.g monkey which eat bananas

  3)under canopy- bare tree trunks; less foliage and fewer branches; home to larger animals

  4)shrub layer- little sunlight; dense with small plants that need less sun; many insects; forest floor is dark & damp & contains litter & decomposers(worms/fungi) that break down litter;rainfall washes nurtients on top of soil away(leaching) so soil below lacks nutrients
• what happens in the tropical rainforest water cycle?

  1)heavy daily convectional rain

  2)trees intercept rain

  3)some rain reach ground

  4)trees take up water

  5)water evaporates

  
• what happens in the tropical rainforest nurtient cycle?

  1)trees shed leaves all year round

  2)decaying vegetation decomposes quickly

  3)nutrients enter soil

  4)shallow roots take up nurtients

  5)trees grow rapidly

  
• whats evapotranspiration


  evaporation of water from plants (transpiration)
• how does the epiphytes (air plants) adapt to TRFs


  -grow attatched to other plants

  -enables them to access sunlight in higher levels of TRFs

  -also get moisture and nutrients from air so dont compete in dense forest floor
• how are drip tips an adaptation of plants in TRFs


  -TRFs have high rainfall

  -if water collects on plants can cause fungus/bacteria

  -drip tips are pointed leaves that enable rain to run off leaf to keep it disease free
• how are buttress roots a helpful adaptation of plants in TRFs


  -large tree roots above soil surface

  -they support the weight of massive TRF trees so they become stable

  -also hold soil together to prevent soil erosion
• how are lianas a useful plant adaptation in TRFs


  -they are climbing woody vines that drape TRF trees

  -they have roots in ground

  -therefore they access sunglight an nutrients
• how is the rafflesia flower adapted to TRFs


  -grows like a parasite on vines and takes host's nutrients

  -lets out strong smell like rotting flesh to attract flies to transport pollen
• how is the poison dart frog adapted to survive in TRFs


  -bright colours to warn off predators

  -eat poisonous ants and store poison in skin

  -can paralyse or kill predators if eaten
• how is the three toed sloth adapted to TRFS


  -extra neck bones allows them to turn head around 270 degrees and detect predators

  -grow algae in fur to create camouflage

  -strong teeth and claws to defend against predators
• where are deforestation rates happening fastest and why

  -South Amercia (Brazil), South east Asia(Indonesia) and Central Africa(D.R Congo)

  -they are LICs and NEEs; trying to increase their income by extracting and selling forest resources

  -also because they have higher forest cover
• what is salinisation and what does it do to plants

  • the build up of salts in soil when water evaporates
  • lower soil fertility as salty soils are too toxic for plants to grow in
• describe the soil in hot deserts


  • sandy/rocky with low organic matter
  • lack nutrients due to fewer plants decomposing
  • no roots of plants to hold soil together so poor soil stability; can easily be blown/washed away