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
What is the equation of % efficiency of energy transfer?
(Net production of trophic level/net production of previous trophic level) x 100
What does GPP stand for?
What is GPP?
Gross primary productivity
What is GPP?
Total amount of chemical energy converted from light energy by plants in given area
What is the energy lost to the environment as heat when plants respire called?
Respiratory loss
What is the remaining chemical energy called?
Net primary productivity
What is the equation of NPP?
NPP= (GPP-R)
What is primary productivity?
When primary production is expressed as a rate
What are the typical units for primary productivity?
KJ ha-1 yr-1/KJ m-2 yr-1
What is NPP?
The energy available to the plant for growth and reproduction
What % of GPP is lost to the environment as heat?
50%
What does an ecosystem include?
All the organism living in a particular area and all the non-living (abiotic) conditions
What makes up biomass an how is it formed?
During photosynthesis plants use energy and co to make glucose and other sugars. Some of the sugars produce during photosynthesis are used in respiration to release energy for growth, rest of the glucose used to make other biological molecules make up the plants biomass
What is biomass?
Mass of living material
What else can biomass be thought of as?
Chemical energy stored in the plants
Whats a consumers net production?
Energy available for the next trophic level
What is an example of a food chain (general)?
Producers, primary consumers, secondary consumer and tertiary consumers
Is it a you move up/down food chains that it becomes more efficient?
Moving up
What do farmers use to reduce pests?
Pesticides, biological agents and intergrated chemical and biological method systems
How do you reduce respiratory loss?
Controlling the conditions they live in o more of their livestocks energy is used for growth and less through respiration
Animals kept in pens where their movement is restricted, indoors and warm no wasting energy through body heat
What are microorganisms an example of?
Saprobionts
What 2 things do saprobionts do?
Feed on remains of dead pants and animals and on own waste
They secrete enzymes and digest their food externally
What is it called when food is digested externally?
Extracellular digestion: Organic molecules are broken down unto inorganic nutrition
What is mycorrhizae?
The symbiotic relationships with the roots of plants
What is a hyphae?
Fungi made up of long, thin strands connecting plants roots
What does hyphae do?
Greatly increase SA of plants roots system, helping the plants absorb ions from soil that are scarce
Why do plants and animals need nitrogen?
Make proteins and nucleic acid
How much of our atmosphere is made up of nitrogen?
78%
How are plants and animals able to use the nitrogen?
Can’t use it as N2 gas bacteria must convert it into nitrogen-containing compounds first
What does the nitrogen cycle show?
How nitrogen is converted into a usable form passed between living organisms and that non-living environment
Why do plants and animals need phosphours?
Make biological molecules e.g phospholipids
Where is phosphate found?
Rocks and dissolved in water in the soil, dissolved in oceans to form phosphate ions
Why do crops take in minerals?
Grow and use them to build their own tissues
When crops are harvested what happens to minerals?
Crops are removed from the field where they’re grown rather than being allowed to die and decompose there
So the minerals ions they contain aren’t returned to the soil by decomposers in nitrogen
What do fertilisers do?
Fertilisers replace the lost minerals, so more energy from the ecosystem can be used for growth to increase efficiency of energy transfers
What are the 2 types of fertilisers?
Natural and artificial
What do natural fertilisers contain?
Contain pure chemicals as powders or pellets
What do natural fertilisers do?
Include manure, composted veg, crop residues and sewage sludge
What happens when more fertiliser is applied that the plants are able to use?
Leaching into waterways
What is leaching?
When water-soluble compounds in the soil are washed away by rain.
Leading to eutrophication
What makes leaching occur more?
Inorganic ions in chem fertilisers are very soluble
Meaning that more likely to leach into waterways
Also, more likely to occur if fertiliser is applied just before heavy rainfall
What type of fertiliser is less likely to cause leaching?
Nautral
Why do natural fertilisers make leaching less likely to occur?
As nitrogen and phosphorus are still contained in organic molecules that need to be decomposed by microorganisms before they can be absorbed by plants
What is more likely to cause leaching phosphates or nitrates?
Phosphates as they are less soluble in water
