Energy and Ecosystems Flashcards
What are producers?
Plants are producers as they produce their own organic matter using atmospheric or aquatic CO2.
What is a trophic level?
Position of an organism in a food chain
What is the definition of a food chain?
Describes the feeding relationships between organisms + the resultant stages of biomass transfer
Producer - Primary Consumer - Secondary Consumer - Tertiary Consumer
What is the definition of a food web?
The interconnection of many different food chains in a habitat
What is biomass and how is it measured?
-The total mass of organic material.
-Measured in terms of mass of carbon or dry mass of tissue per given area.
How does energy enter an ecosystem?
Energy enters an ecosystem when producers carry out photosynthesis, capturing energy from the sun and storing it as chemical energy.
How is energy transferred between organisms in the ecosystem?
Producers use energy from the sun to produce their own food and they are eaten by primary consumers who are eaten by secondary consumers and so on, so energy flows from one trophic level to the next.
-Only 10% of chemical food energy is passed on between organisms in food chain
How is energy lost along a food chain?
- Excretion
- Movement
- Respiration
Remaining energy is used to form biomass
How do you calculate the efficiency of energy that is transferred from one trophic level to the next?
% Efficiency = (Energy available after transfer/ Energy available before transfer) x 100
What is the definition of a decomposer?
Organisms that break down dead organic material and waste + recycle nutrients
What is meant by gross primary productivity (GPP)?
The chemical energy store in plant biomass in a given area or volume. It is the TOTAL energy resulting from photosynthesis
What is net primary productivity (NPP)?
The chemical energy store in plant biomass taking into account energy that is lost due to respiration and this is used in plant growth or reproduction.
It’s the energy left over that’s available to the plant to create new biomass available to the next trophic level.
NPP= GPP - R
How do you calculate the net production of consumers (N)?
N= I - ( F+R )
I= the chemical energy stored in ingested food
F= the chemical energy lost to the environment in faeces and urine
R= respiratory losses
N= energy to form new biomass
Define primary + secondary productivity
-The rate of primary or secondary production
-measured as biomass in a given area over a given time period eg.kJ ha–1 year-1
-kJ is the unit for energy
-recorded as per unit area to standardise results so environments can be compared
-per year to take into account the impact of seasons + provides an annual average to allow fair comparisons
Explain why the length of food chains is limited?
Energy is lost at each trophic level so there is insufficient energy to support a higher trophic level
