IB Biology HL : energy transfers ecosystems

food

fundamentral concepts

• energy is lost as they go up the food chain

• ecosystems are affected by changes in the availability of energy and matter

• biological processes depend on energy flow through earth’s system

• the sun is the main source of fuel for ecosystems

• food is a biofuel required by organisms to acquire energy for internal living processes

• energy available to do useful work decreases as it’s transferred from organism to organism

• energy flows though food webs in one direction from producers to consumers to decomposers

• ecosystems are affected by changes in the availability of energy and matter.

• humans are part of the earth ecosystem and influence energy flows through these systems

why does the total biomass of organisms higher up in the foodchain higher

• some parts are not consummable; bones, hooves, horns

• not all biomass is used; some isn’t consummed

• some is lost to respiration

chemoautotrophs

oxidation of non-organic molecules, in unhospital conditions, eg sewers, geothermal vents

biomass

dry mass of organisms

pyramid of biomass advantages or disadvantages

gram m^-2

good

• takes into account mass

bad

• doesn’t take account of variation around year

• some of the mass doesn’t get used up

pyramid of energy

kcal m^-2 yr^-1;

takes into account year on year variation

always are pyramid shaped

adaptations of maram grass

• high resistance

• fine, narrow leaves resisting strong winds and sandblasting

• thick outer layer of waxy cuticle resists water loss

• rolled leaves reduce SA for evaporation, conserving water

• hairs inn the inner leaf epidermis reduce evaporation and air flow over the stomata to tolerate dessication

• sunken stomata and rolled leaves decrease the humidity gradient and reduce water loss

• extensive root systel allows for coping with moving sand and low nitrate in top soil

maram grass in embryo dunes

few odd plants

maram grass primary dune

larger tufts

little water

more biomatter

maram grass in mature dunes

less; more competition

range of tolerance and zones of stress

• zones of stress; end of zone of tolerance

mangroves conditions

• brackish water: not salty nor fresh

• constant flooding

• little light

mangroves/ Rhizophora apiculata adaptations

• stilt roots; gives structural integrity

• halophyte; can survive in salty water

• specialised roots; pneumatocytes; they respire even in waterlogged soil

• seeds start to germinate while still attached to parent plant

coral reef conditions

• warm water

• sunlight for zooxanthellae

• salt water; won’t growth at mouth of rivers

• clear water; so no farming/freshwater treatment. no sediment

• moderate wave action; not too strong

• need inundation