topic 5 (energy transfer in ecosystems) Flashcards
what is a producer?
organism that makes its own food
what is a consumer?
organism that consumes on another organism to obtain its energy, rather than directly using energy from sunlight
what is a primary consumer?
organism that directly eats a producer
what is a secondary consumer?
organism that eats a primary consumer
what is a tertiary consumer?
organism that eats a secondary consumer
what is a saprobiont?
decomposer that breaks down complex material in dead organisms into simple matter
what is biomass?
the mass of living material
what does a food chain do?
describes a feeding relationship where producers are eaten by consumers
what is a stage in a food chain called?
trophic level
what does an arrow on a food chain represent?
the direction of energy flow
what does a food web represent?
how food chains in a habitat link together
how can you estimate the chemical energy stored in biomass?
by burning biomass in a calorimeter
what can biomass be measured in terms of?
the mass of carbon an organism contains, or the dry mass of its tissue per unit area
what is dry mass?
mass of an organism with all the water removed
how can you find the dry mass of an organism?
sample of an organism dried in a low temperature oven
weighed at regular intervals
when mass ecomes constant all water has been removed
scale up to total population/area being investigated
how much carbon is present in dry mass?
50%
how does a calorimeter find the chemical energy given off?
sample of dry biomass burnt
energy used to heat a known volume of water
change in temperature of water used to calculate the chemical energy of the dry biomass
what is gross primary production?
total amount of chemical energy converted from light energy by plants, in a given area
how much of the GPP is lost as heat to the environment when plants respire?
50%
what is respiratory loss?
GPP lost to the environment when plants respire
what is the net primary production equation?
gross primary production - respiratory loss
what is net primary production?
energy available to the plant for growth and reproduction
energy stored in a plant’s biomass
energy available to organisms at the next stage of the food chain
what is primary productivity?
total amount of biomass in a given area at a given time
where do consumers store chemical energy?
in their biomass
how do consumers get energy?
ingesting plant material, or animals that have eaten plant material
how much energy is lost between trophic levels?
90%
why is energy lost between trophic levels?
not all of the organism is consumed
some parts of an organism are lost in faeces if they cannot be digested
some energy lost in excretory materials
what is the formula for net production of consumers?
net production=
chemical energy ingested in food - (chemical energy lost in faeces/urine/respiration)
what is the net production of consumers also called?
secondary production/productivity
why do most food chains only have 4/5 levels?
insufficient energy to support a large enough breeding population at a higher trophic level than this
is the mass of organisms higher/lower at a higher trophic level?
lower
how does the energy available change as you go higher up the food chain?
decreases
what is the equation for percentage efficency?
(energy available after the transfer/ energy available before the transfer) x 100
what are two methods farmers use to increase the efficency of energy transfer?
reduce the energy lost to other organisms
reduce the energy lost through respiration
how can a food web be simplified?
by getting rid of pests
what are methods of pest control?
use chemical pesticides and biological agents
how can respiration loss be reduced?
keep animals in pens to restrict their movement
keep pens indoors and warm- less energy lost by generating body heat
how do pens increase energy conversion rate?
movement restricted so less energy used in muscle contraction
environment kept warm to reduce heat loss
feeding controlled so max growth with no waste
predators excluded- no loss in food web
