chapter 23 - ecosystems Flashcards
what are the abiotic factors affecting ecosystem
light - for photosynthesis
h20 availability - photosynthesis
o2 availability - respiration
temperature - enzymes / migration
edophic ( soil) factors - type of soil/ soil pH
what are the biotic factors affecting competition
competition
predation
diseases
what are trophic levels
stages in food chain
what are the tropic levels
producers –> primary consumers –> secondary consumers –> tertiary consumer –>
what is biomass
mass of living material in an area or organism without h20
why is h20 not considered as biomass
water levels fluctuate depending on the environment and times of the day so is not a true representation on amount of energy in organism
what happens to biomass up the tropic levels
biomass decreases
how is biomass measured
calorimeter - measures calories within organism
how does calorimeter work
1)collect sample
2)kill sample
3)put in oven at 80degrees celcius to evaporate water
4) point where mass stays same is biomass
why shouldnt you insert sample in oven at 100 degrees celcius
organic matter may decay so results not valid
what are unit of biomass
land animals - gm^-2
ocean animals - gm^-3
what is ecological efficiency
efficiency in which biomass is transferred from one tropic level to the next
why is ecological efficiency never 100%
sunlight reflected
other factors affecting the photosynthesis rate
some energy used up for photosynthesis to occur
some energy lost as thermal energy through respiration
some energy lost by excretion
some parts of food not eaten
what are agricultural ways to increase efficiency
keep animals indoors
keep fences to decrease movement
feed animals high energy content
vaccination
genetic engineering/selective breeding
what are decomposers
feed on dead organic matter
saprophytic
secrete enzymes for external digestion
what are detritivores
internal digestion
feed on dead organic matter
increase surface area on food to increase decomposition rate
describe carbon cycle
1) consumers release co2 to atmosphere by respiration and producers take in co2 from atmosphere by photosynthesis
2) co2 transmitted to consumer as it eats producer
3) consumer dies and decomposers feed on organic matter releasing co2 to atmosphere
4) undigested material becomes fossil/fossil fuels
5) fossil fuels burnt for energy and combustion releases co2
what is nitrogen used for
amine group for proteins
what is nitrification
ammonium ion ( NH4+) turned to nitrite ( NO2-) then to nitrate ( NO3-) by oxidation
what bacteria converts ammonium ion to nitrite ion
nitrosomonas
what bacteria converts nitrite ion to nitrate ion
nitrobacter
what is ammonification
nitrate ion and nitrate ion converted to NH4+ which is converted to ammonia ( NH3) by decomposers
what is denitrification
NO3- ( nitrate) converted to N2 in by denitrifying bacteria , pseudomonas, in anaerobic conditions
what is nitrogen fixation
N2 + 3H2 —– 2NH3 catalysed by nitrogenase found in bacteria such as azotobacter and rhizobium
