Topic 5: Energy and ecosystems Flashcards
What is biomass?
The total mass of living material or chemical energy stored in the organism
What provides the energy for all ecosystems?
Solar radiation
What is most of the energy produced by the sun in plants used for?
To make sugars used for respiration
What do animals use the energy from respiration for?
(4 marks)
-Movement
-Maintaining body temperature
-Growth
-Reproduction
What are the 2 ways biomass can be measured?
-Dry biomass
-Mass of carbon
What is a benefit of using pyramids of energy over biomass?
More accurate: As 2 organisms of the same biomass could store different amounts of energy
What are the limitations of using pyramids of biomass/energy?
(3 Marks)
-Can only use a small sample as it needs to be destroyed: may not be representative
-Animals have to be killed
-Waste inside animals will be included
What is the Gross Primary Production (GPP)?
The total solar energy that producers convert to organic molecules
How do you measure biomass?
-A sample of the organism is dried at a ow temperature.
-The sample is weighed
-Drying and weighing is repeated until the mass becomes constant
-Mass of carbon in the sample is about 40% of the dry biomass.
Why is the drying and weighing repeated until mass becomes constant?
To ensure all of the water has been removed.
Why must the temperature be low when the sample is being dried?
To prevent combustion of the organic molecules which causes biomass to be lost in the form of carbon dioxide.
How could you estimate the energy store of a sample of dry biomass?
-Burn a sample of biomass completely in a bomb calorimeter
-The heat energy released from this combustion is used to heat a known volume of water
-The temperature change in the water can be measured to calculate the chemical energy
Why do producers convert as little as 1% of the available solar energy into chemical energy? (4 Marks)
- Solar energy is reflected back into space or absorbed by the atmosphere
-Not all wavelengths of light can be absorbed by photosynthetic pigments
-Light may pass through a leaf without hitting a chloroplast.
-There may be others factors limiting the rate of photosynthesis
What is the Net Primary Production (NPP)?
The chemical energy store in plant biomass (after respiratory losses to the environment have been taken into account).
How do you calculate NPP?
-Subtracting the respiratory losses to environment from the Gross Primary Production.
NPP = GPP - R
