M6, C23 Ecosystems Flashcards
define ecosystem
all the organisms living in a certain area and all the non-living conditions found there
what are biotic factors
The living features of an ecosystem
eg. predators or food
what are abiotic factors
The non-living features of an ecosystem.
eg. temperature, rainfall, pH, soil nutrient availability
define habitat
the place where an organism lives within an ecosystem
How does light intensity affect an ecosystem
It affects the growth of producers.
Determines the rate of photosynthesis in plants.
how does temperature affect an ecosystem
affect the growth of producers (rate of photosynthesis)
could provide better/worse living conditions for organisms
why do we say that ecosystems are dynamic systems
the biotic and abiotic factors are always changing
how does water availability affect an ecosystem
affects photosynthesis in plants (producers)
water organisms need a plentiful supply of water to survive
how does oxygen availability affect an ecosystem
needed for respiration in organisms
how does soil type affect an ecosystem
certain plants will grow in certain pH of soil (producers)
needs to be soft enough to allow plants to grow
define trophic level
a stage in a food chain that’s occupied by a particular group of organisms
define producer
an organism that produces organic molecules using sunlight energy (plants)
define consumer
an organism that eats other organisms
draw a simple food chain
oak tree -> caterpillar -> starling -> cat
define biomass
dry mass of living material
producers store energy as biomass
Explain why biomass decreases at each level in a food chain
Energy is lost from an organism because…
- not all of an organism may be eaten,
- parts of an organism may be indigestible,
- some energy is transferred to the environment through metabolic heat,
- some energy is lost through excretion
give some examples of how human activities have improved ecosystems and the transfer of biomass
Herbicides - kill weeds that compete with agricultural crops for energy, grow faster, increasing productivity
Fungicides - kill fungal infections that damage agricultural crops
Insecticides - kill insect pests that eat and damage crops, less biomass is lost
Fertilisers - provide crops with minerals, increases efficiency of energy conversion
Rearing livestock involves controlling the conditions so more energy is used for growth, more biomass produced.
define decomposer
organisms that consume organic material (roots, bones)
define detritivores
an animal which feeds on dead organic material
define saprotroth
an organism that feeds on decaying organic matter
what do pyramids of biomass show
the total dry mass of all organism at each trophic level at a given time
The area of the bar is proportional to the dry mass of all the organisms at that trophic level
how could measure the amount of biomass in a material
Easiest way is to measure mass of fresh material
Water content in organisms must be removed
Organism heated in an oven at 80ºC until all the water has evaporated
Dry organism weighed to measure mass in grams
The figure is multiplied by the number of organisms present in a given area
what is the role of photosynthesis in the carbon cycle
carbon is absorbed by plants when they carry out photosynthesis
it becomes carbon compounds in plant tissues
this is passed onto primary consumers when they eat plants and then onto secondary and tertiary consumers
what is the role of decomposition in the carbon cycle
decomposers secrete enzymes which break down the carbon compounds in dead organic material
they then absorb the products of digestion for use in respiration
what is the role of respiration in the carbon cycle
carbon is returned to the air as all living organisms carry out respiration which produces carbon dioxide
what is the role of combustion in the carbon cycle
if dead organic matter ends up in places where there aren’t any decomposers (oceans/bogs), its carbon compounds can be turned into fossil fuels over millions of years
the carbon is released when they’re burnt