Energy and Ecosystems Flashcards
How do plants use the sugars from photosynthesis?
- Primarly as respiratory substrates
- To synthesis other biological molecules
What is biomass?
Total dry mass of tissue or mass of carbon measured over a given time in a specific area
Suggests the units for biomass?
- When an area is being sampled: gm⁻²
- When a volume (e.g a pond) is being sampled: gm⁻²
How can the chemical energy store in dry mass be estimated?
Use calorimetry.
Energy released = specific heat capcity of water x volume of water (cm³) x temperature increase of water.
Why is bomb calorimtery perferable to simple calorimetry?
Reduces heat loss to surroundings.
How could a student ensure that all water had been removed from a sample before weighing?
Heat the sample and reweigh it until the mass reading is contant.
Define gross primary producting (GPP)
Total chemical energy in plant biomass within a given volume or area.
Define the net primary productivity (NPP).
Total c͟h͟e͟m͟i͟c͟a͟l͟ ͟e͟n͟e͟r͟g͟y͟ ͟a͟v͟a͟l͟i͟a͟b͟l͟e͟ for plant g͟r͟o͟w͟t͟h͟, plant reproduction and energy transfer to other trophic levels after respiratory losses.
Give the mathematical relationship between GPP and NPP.
NPP = GPP - R
Where R represents respiratory losses
Why is most Sun’s energy not converted to organic matter?
- Most solar energy is absorbed by atmosphere or reflected by clouds.
- Photosynthetic pigmets cannot absorb some wavelengths of light.
- Not all light falls directly on a cholorophyll molcule.
- Energy is lost as health during respiration/photosynthesis
How can the net production of consumers be calcluated?
N = I-(F+R)
I: chemical energy from ingested food
F: energy lost as faces and urine
R: respiratory losses
Why does biomass decrease along a food chain?
- Energy lost in nitrogenous waste (urine) & faeces
- Some of the organims is not consumed.
- Energy lost to surroundings as heat.
Define primary and secondaring productivity.
- Rate of primary of secondary production.
- biomass in a specfic area over a given time period e.g. kJ ha⁻¹ year⁻¹
Outline some common farming practices used to increase the effciency of energy transfer.
- Exclusion of predators: no energy lost to other organisms in food web.
- Artificial heating: reduce energy lost to maintain constant body temperature,
- Restriction of movement.
- Feeding is controlled at the optimum.
Give a general equation for % efficiency.
Energy converted to a useful form (j) x 100 / total energy supplied (J)
