C4.2 transfers of energy and matter

how energy enters systems

light

how energy leaves systems

heat

open system

allows matter to go in and out

closed system

matter doesnt leave or enter system

earth system type

closed

systems theory

explains how systems interact with each other and their environment and predict what would happen if sth in or around a system is changed

laws that ecosystems obey

• law of conservation of mass

• law of thermodynamics

producers

photosynthetic organisms, transform water and air into food

flow of energy through a food chain

process of passing energy from one organism to another through feeding

what x→z indicates

x is eaten by z

food chain

linear set of connections from producers to consumers with only one species at each trophic level

food web

more complete picture since multiple producers may be eaten by one consumer

decomposers

saprotrophs and detritivores, break down non living food sources

adaptations of decomposers

digestive enzymes that convert organic matter into a more usable form, eg proteins turned into ammonia nh3, nitrogen in turn converted into NO3 nitrates by bacteria (minotaur beetle)

humus

rich black layer of soil

autotrophs

capable of producing their own organic molecules as a source of food

photoautotrophs

use light energy from the sun combined with inorganic molecules to obtain chemical energy in form of carbon compound such as glucose

carbon fixation

ability to convert inorganic co2 into organic molecules useful for energy and growth

chemoautotrophs

capable of using inorganic molecules such as co2 or H2S as an energy source for building more complex useable molecules

egs photoautotrophs

• cyanobacteria

• clover

• algae

• pine trees

chemoautotrophs

• sulfur oxidising bacteria

• nitrogen oxidising bacteria

• iron oxidising bacteria

heterotroph examples

• zooplankton

• sheep

• insects

• fish

what heterotrophs do with food

digest proteins into amino acids, lipids into fatty acids, and dna and rna into nucleic acids

process of integrating nutrients into usable substances in the tissue of the body

assimilation

what heterotrophs do with sugar etc

oxidise it

trophic level use

indicate how many organisms the energy in the system has flowed through

first trophic level

producers

second trophic level

primary consumers

problems with food web representation

cant show trophic levels very well

pyramid of energy use

show how much and how fast energy flows from one trophic level to the next in a community

units pyramid of energy

energy per unit area per unit time, ie kJ per m² per year (kj m^-2 yr^-1)

whats impossible in energy pyramid

have a higher trophic level wider than lower trophic level because organisms cant produce energy only transfer it inefficiently

how much percent energy is used from the previous step

10-20%

reasons why not all the energy present can be used

• not all of organism is ingested, some is discarded as waste

• not everything swallowed can be digested and use, eg seeds in animal feces

• some organisms die without being eaten by organism from next trophic lvl

• considerable heat loss from celllular respiration at all trophic levels, especially endotherms

why heat energy = lost isnt a problem

sunlight

number of trophic levels

up to six, but most have four

what limits amount of trophic levels

hm energy enter the ecosystem

biomass of trophic level

estimate of the mass of all organisms on that level

biomass

dry weight of an organism, because actual mass contains a lot of water

unit for biomass

gram per metre squared per year (g/m^-2/yr^-1)

what influences biomass

amount of sunlight reaching photosynthetic producers = sunnier parts of the world can produce more biomass eg phytoplankton near equator vs no

why biomass decreases up trophic levels

subsequent levels have continuing appetite for energy

cooler biomes

lower biomass ergo can support less organisms

biome

large community of plants and animals; tend to cover wide expanses, often on continental scale

primary production

biomass generated by activity of producers such as photosynthetic organisms when they fix carbon and make carbon compounds that can be used as a food source. measured in gm^-2y^-1

eg of molecule lost from accumulated biomass

co2 during celllular respiration, waste product excretion such as urea

what isnt necessarily passed on to next trophic level

both biomass and energy

secondary production

conversion of one carbon molecule into another within a consumer eg glucose to lipids

biosphere

all places where life is found

lithosphere

all places where rocks are found

what produces methane

microbes such as archaea, especially important in digestive tracts of mammals as they significantly contribute to climate change

net producer vs consumer of carbon

carbon source vs carbon sink

importance of fire

burns away fallen branches, gives way for renewed growth, plus some seeds can only germinate when exposed to fire eg pinus contorta

peat

heterogenuous mixture, minimum 30% biomass

keeling curve

shows avg trend and seasonal changes of co2 concentration which are due to photosyhtetic organisms activity

elements important for life that are cycled and passed through the food chain

hydrogen oxygen calcium potassium sodium iron phosphorus etc. when organisms die, these are either passed on to the next trophic level or to detritivores and decomposers