5.3 - Energy and ecosystems Flashcards
define species
group of organisms that can breed to produce fertile offspring
define population
a group of organisms of the same species occupying a particular space at a particular time
define community
multiple species populations living in one area
define ecosystem
relatively self-contained unit consisting of community/ies of species interacting with each other and abiotic factors of their environment
define biotic and give examples
living
e.g predation, disease
define abiotic and give examples
non-living
e.g light intensity, temperature, pH, moisture, humidity
define autotrophs
organisms that use energy from Sun to produce their own food
define heterotroph
organism that cannot synthesise their own food
how much energy is passed on between organisms in the food chain
10% (chemical food energy)
How is 90% of energy lost?
- uneaten parts e.g bones
- decay of dead material (by bacteria)
- excretion
- exothermic reactions e.g heat lost via respiration
percentage energy efficiency formula
energy available after transfer/energy available before transfer x 100
how can biomass be measured?
dry mass of carbon or dry mass of tissue per given area per given time
how does bomb calorimetry work?
sample of known mass burnt in pure oxygen and submerged in water
temperature of water used to calculate energy in sample
define net primary productivity
rate at which energy is transferred into organic molecules that make up new plant biomass after respiratory losses
define gross primary productivity
rate at which energy is incorporated into organic molecule in plants in photosynthesis, chemical energy store in plant biomass in a given area/volume in a given time
