Topic 5: Energy Transfer and Nutrient Cycles Flashcards
What is biomass?
Matter from recently living organisms used for bioenergy production
Name one way energy is transfered through the living organisms?
When organisms eat each other organisms
How is biomass measured?
Measured in terms of the mass of carbon that an organism contains or the dry mass of its tissue per unit area
What is dry mass?
Mass of the organism with the water removed
Why is dry mass more reliable than wet mass?
Water content of living tissue varies, so mass would constantly be changing
How do you workout dry mass?
Sample is dried, often in an oven set to a low temp sample is weighed at regular intervals.
Once the mass becomes constant you know that all the water has been removed
How much percenTage does mass of carbon taken is to be of the dry mass?
50%
What is the unit for dry mass?
Kgm-2
What are pests?
Organisms that reduce the amount of energy available for crop growth and decrease NPP of crops
What is bad about pests?
Reduce the amount of energy available for humns
How can you kill pests?
Using chemical pesticides and biological agents
So crops lose less energy and biomass, increased efficiency of energy transfer to humans
How can you reduce respiratory loss?
By controlling condition that they live in, more of their energy is for growth
Less is lost through respiration
What is good about reducing respiratory loss?
More food can be produced in a shorter space of time, often at a lower cost
What is bad about reducing respiratory loss?
Raises ethical issues, people think conditions cause the animals pain or distress
What is an example of how to reduce respiratory loss?
Animals to be kept in pens and often kept warm
What happens as you move up a food chain (energy transfer)?
Becomes more efficient
What do food chain/webs do?
Show how energy is transferred through an ecosystem
What are the stages in a food chain called?
Trophic level
What do decomposers do?
Break down dead or undigested material, allowing nutrients to be recycled
What do most farming practices aim to increase?
Aim to increase the amount of energy that is available for human consumption
How do we increase the amount of energy that is available for human consumption?
Increasing NPP of crops and NP of livestock
How can you increase NPP of crops?
Energy lost to other organisms (pests reduced through simplification of food webs)
How can you increase NP of respiration?
Energy lost through the respiration of livestock can be reduced
How do consumers get energy?
Ingesting plant material, or animals that have eaten plant material
What % of energy is lost through each tropic level?
90%
Why is so much energy lost through each trophic level?
Some parts are indigestible, so are egested as faeces
Chemical energy stored in there parts is lost to the environment some lost through respiration
What is the equation for net production?
Chemical energy in ingested food - (chemical energy lost in faeces and urine + energy lost through respiration)
What is another name for net production?
Secondary production