Energy and Ecosystems Flashcards
What is NPP?
The chemical energy store in plant biomass after respiratory losses have been taken into account
What is GPP?
Chemical energy store in plant biomass in a given area
What is dry mass?
The mass of a dry object (once water has evaporated)
How is energy lost between trophic levels?
- Excretion/Egestion
- Respiratory losses
- Heat losses
How is energy lost from the sun to plants?
- Reflection of light
- Not all light hits plants
- Not all wavelengths are absorbed
What is an equation for NPP?
NPP = GPP - R
What does ‘R’ represent in the NPP equation?
Respiratory losses
How do calculate the net production of consumers (N)?
N = I - (F + R)
What do I and F represent in the equation for N?
I represents the chemical energy in ingested food. F represents the chemical energy lost in faeces and urine.
What is chemical control?
Includes pesticides and herbicides, e.g. DDT which is no longer used due to accumulation as it goes up the food web and increases in toxicity
What is biological control?
Involves the sue of natural predators to remove pests
What are the pros and cons of chemical control?
Pros: Efficient and controlled
Cons: Expensive, not specific and loss in biodiversity
What are the pros and cons of biological control?
Pros: Cheaper, better for the environment, don’t need to repeat
Cons: Hard to control, don’t know the effect.
How does intensive livestock increase the efficiency of energy conversion?
- Limits the movement of animals, so loss of energy through respiration is minimal
- Food is readily available, so minimal movement is needed for food
- Warm as there are many animals in one space, so reduction in energy for heat
What are two features of intensive rearing?
Large number of animals in small space and use of antibiotics so that energy isn’t used for immunity.
