3.2.2: The structure and functioning of ecosystems Flashcards
Input
Material or energy moving into the system from outside
Output
Material or energy moving from the system to the outside
Energy
Power or driving force behind the system
Stores/components
The individual elements or parts of a system
Flows/transfers
The links or relationships between the components
Positive feedback
A sequence of events that amplifies or increases a change, promotes environmental instability, spirals out of control
Negative feedback
A sequence of events that dampen or reduce the effects in a system promoting dynamic equilibrium
Dynamic equilibrium
This represents a state if balance within a constantly changing ecosystem
Biotic components
4
Animals/birds
trees/plants
bacteria
insects
Abiotic components
6
rocks soil air water climate light
Food chains
Trace single routes of pathways from one organism to another
Example of a food chain in deciduous woodland
plant > insect > toad > snake > fox
Food web
Interconnecting web of food chains which are linked
Needed for growth, movement and reproduction?
biological molecules and vitamins
Examples of biological molecules
3
fats, carbohydrates and proteins
Consumers
Organisms that eat plants or other animals
Example of a food web
marine or aquatic ecosystems illustrate food webs well
Why are marine or aquatic ecosystems good examples of food webs
4 reasons
- the sea provides the basic requirements for life,
- there are more favourable conditions for organic production in the sea than on land,
- water and oxygen are abundant and carbon dioxide is readily available,
- temperature variations are less extreme than on land.
Basic requirements for life
4
water
nutrients
heat
light
Trophic level
Position an organism occupies in a food web
Producers
self-feeding autotrophs that produce energy through photosynthesis
Examples of producers
3
grass, oak leaf, phyloplankton
Primary consumers
vegetarian herbivores eat plants
Examples of primary consumers
3
earthworms, caterpillars, zooplankton
Secondary consumers
meat eating carnivores eat animals
Examples of secondary consumers
3
house sparrow, blue tit, fish
Tertiary consumers
Top predators (omnivores) eat small animals
Examples of tertiary consumers
3
tawny owl
hawk
great white shark
Gross primary productivity
total energy fixed by green plants
GPP
gross primary productivity
NPP
net primary productivity
Net primary productivity
Energy from GPP after respiratory losses, produced new biomass
NPP equation
NPP = GPP - R
Most productive ecosystem
tropical rainforest
Secondary productivity
animal productivity
Primary productivity
plant productivity
What is vital for sustaining life in an ecosystem
constant recycling of nutrients
Stores in an ecosystem
3
biomass, soil and litter
Inputs into an ecosystem
2
rainfall and weathering of parent rock
Ouputs out of an ecosystem
2
surface runoff and leaching
Transfers in an ecosystem
3
littering, decomposition and plant uptake
Factors that influence the rate of weathering and therefore nutrient availability
2
temp and moisture
Factors that influence the rate of photosynthesis
3
water, availability of sunlight and temp
Optimum temperature for metabolic activity
15-25 degrees C
Units for primary productivity
grams of carbon per metre3 per year
gCm-3yr-1
Tropical rainforest primary productivity
2000 gCm-3yr-1
Tundra primary productivity
140 gCm-3yr-1
