Organisms and their environment Flashcards
food chain definition
chart showing the flow of energy from one organism to the next (beginning with a producer)
food web definition
network of interconnected food chains showing energy flow in part of an ecosystem
decomposer definition
an organism that gets its energy from dead or waste organic matter
ecosystem definition
unit containing all their organisms and their environment, interacting together, in a given area
community definition
all populations of different species in an ecosystem
trophic level meaning
position of an organism in a food chain
interdependance meaning
the way in which living organisms depend on each other to stay alive, reproduce and grow
photosynthesis equation
6CO2+ 6H20-> C6H120+6O2
predators meaning
organisms that hunt and kill their food
prey meaning
organisms that are eaten by predators
apex predators meaning
carnivores with no predators
what do the arrows in a food chain represent
they represent the direction in which energy (from food) flows from one organism to the next
prey and predator_ type of relation
cyclical correlation
what do pyramids of numbers show and how
- how many organisms there are at each level
- through size of box
general rule for pyramid of numbers
the larger an organism is, the less of them there are (number-wise)
what shapes can a pyramid of number acquire?
any! doesn’t have to be pyramid shaped
what can you not change in a pyramid of numbers?
trophic level
what does a pyramid of biomass show
how much DRY mass the creatures at each level would have
shape of pyramid of biomass
nearly always pyramid
why nearly always pyramid shaped?
mass of organisms must decrease as go up– 10kg of grass cannot feed 50kg of cows
criticisms of pyramids of biomass
- measurements= taken at a moment in time (so does not consider how fast it grows). i.e. grass, grows quickly but is grazed to low biomass
- phytoplankton= live for few days then are eaten, so biomass only represents a few days growth. this would lead to inverted pyramid
- biomass can vary with seasons (i.e. deciduous trees= lose leaves in winter)
solutions to problems with pyramids of biomass
calculate biomass over a reasonable period of time (i.e. 1 year)
when calculating dry mass, why important to leave out water?
- not nutritionally valuable
- unreliable as some absorb more water, depends on weather, etc)
how much energy is passed on to next organism?
10%
why not all energy transfered
as used in heat, movement, respiration, life processes, egested, remains in dead organisms, not fully eaten (i.e. bones)
which food chains are the most efficient
shorter ones
efficient food chain
wheat-> humans
how do farmers try to maximise meat production?
- reducing movement
- keeping them warm in winter
