biomass transfer through ecosystems Flashcards
what is a trophic level?
each stage in a food chain
what are food chains/webs used to demonstrate?
transfer of biomass (energy) through organisms in an ecosystem
describe the first trophic level
producer - an organism that converts light energy into chemical energy via photosynthesis
why is there a limited number of trophic levels?
there is not sufficient biomass and stored energy left to support further organisms
what is the role of decomposers?
break down dead organisms and release nutrients back into the ecosystem
what is ‘biomass’?
the mass of living material present in a particular place or organisms
how would you calculate the biomass at each trophic level?
biomass present x total number of organisms in trophic level
what is meant by ‘ecological efficiency’?
the efficiency by which biomass/energy is transferred
what makes up the biomass?
cells and tissues composed of carbon compounds
what are units for biomass on land and water?
land = gm-2
water = gm-3
how is biomass measured?
discount water and measure the mass
why is it important to not consider the water and use dry mass?
organisms have varied amounts of water
what are the limitations of pyramids of biomass?
fails to consider how climate plays a role in trophic level activities
how are biomass and energy linked?
light energy is captured by plants and transferred to organic compounds, forming biomass.
- therefore biomass can be equated to energy content
what is meant by gross primary production?
the rate at which chemical energy is stored by producers
what is meant by net primary production?
the energy left over after respiration in plants
why is a rabbit more energy efficient than a lizard?
lizard
- mammals have consumed less energy available for next consumer
- mammals have a high body temp so requires a high rate of respiration and loses a higher proportion of energy
- higher proportion of food the lizard eats can be converted into new cells/tissues so a higher proportion of energy available to predator
how is net primary production calculated?
gross primary production - energy used in respiration
how can energy be lost from plants? (5 points)
- reflection from leaf surface
- transmission through leaf
- light not correct wavelength
- limited photosynthesis due to water availability
- energy lost via photosynthesis
how can energy be lost from consumers? (4 points)
- not all biomass of organism is eaten, e.g. roots or bones
- heat loss via movement/respiration
- some parts of organism eaten are not digested
- excretory material, e.g urine
what is the calculation for ecological efficiency?
(biomass or energy available AFTER transfer / biomass or energy available BEFORE transfer) x 100
what is the calculation for energy consumed?
biomass + respiration + waste
describe and explain how energy efficiency differs through an ecosystem
- first stage = producer
- 1-3% light energy is converted into chemical energy in photosynthesis due to factors such as reflection, transmission, incorrect wavelength
- second stage = consumer
- 10% energy is used
- energy lost due to heat/respiration but the organisms consumed contain more energy which is transferred to form biomass
how does intensive rearing of animals create more energy efficient transfer?
- converting smallest amount of food energy into greatest quantity of animal mass
- ensure that energy goes into growth rather than other activities
what methods do intensive farms use to maximise output? (5 points)
- specially bred animals for high growth rate
- highly digestible diet including growth hormones and antibiotics
- restricted movement to reduce energy output
- exclusion of predators
- slaughtered young as more energy is transferred to biomass
