Energy transfers in ecosystems

  • Created by: DonaJ2002
  • Created on: 13-01-20 14:48
In any ecosystem, what do plants do?
Plants synthesis organic compounds to make their food using light energy and CO2 on either land (atmospheric)/ aquatic(dissolved H2O) based
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What are the sugars from photosynthesis used for?
1.Used in respiration to release energy to grow 2. Make other biological molecules (e.g. cellulose)that make up plant's biomass
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Define plant biomass and state what happens to the energy stored in an organism
Organism's chemical energy store- this energy can be passed along the food chain to different trophic levels
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Describe how energy is transferred through an ecosystem
When primary consumers(herbivores) eat producers, SOME energy from producers transferred to primary consumer. Some of primary consumer's energy transferred to secondary consumer when primary is consumed by secondary consumer, secondary eats tertiary
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State how biomass can be measured
1. Carbon mass 2. Dry mass of tissue per given area
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Define biomass
Organism's mass after water has been removed
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How can you measure dry mass?
1. Remove water by drying organism in an oven for several days 2. Weigh at regular intervals 3. Once mass becomes constant=all H2O removed.
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What can the dry mass be used for?
Estimate total dry mass(biomass) of total population/area investigated
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Define carbon mass
Mass of carbon the organism has- water content not taken into account
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How can you relate dry mass and carbon mass?
Carbon mass is half the dry mass
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Why is dry mass used instead of wet mass?
Water content of living tissue varies
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Explain how chemical energy is estimated and what part of the process is the chemical energy
Burn biomass in calorimeter and the amount of heat energy released= amount of energy in organism but this calculation is made by using temperature change of known volume of H2O as a result
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Define Gross Primary Production (GPP)
Chemical energy store in plant biomass in given area/volume: GPP= NPP-RL
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Define+ Explain Net Primary Production (NPP)
Chemical energy store in plant biomass after respiratory losses taken into account(NPP=GPP-RL) and is the energy available for plant growth+respiration and the energy for organisms in next trophic level of food chain
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How much of GPP is lost and how is it lost?
50% GPP lost as heat energy to environment when plants respire= respiratory loss (RL)
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Define Primary Production
Total biomass (chemical energy in given area+time (REMEMBER: Like rate so, units can be
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Explain how consumers get energy AND explain how this energy is lost
Consumers get chemical energy by eating organisms below their trophic level; some energy transferred to next trophic level by 1.indigestible faeces to environment 2.RL 3.excreting urine 4.their bones+roots not eaten
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What is the term given to the remaining energy in consumer's biomass after RL, Urine Excretion, Their bones/roots not being eaten and Indigestibles Egested as faeces?
Energy remaining after this is hence called Consumer's Net Production (CNP) (what consumer produces in total after losses occur) THIS energy is available for next trophic level
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How do you calculate consumers net production(CNP)?
CNP= I - (F+RL) where: I= chemical energy in Ingested food and F= chemical energy in Faeces and Urine and RL= Respiratory loss
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What is consumer net production also known as and why for each?
EITHER: 1. Secondary production (as primary is producer) 2. Secondary productivity IF expressed as RATE
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How do you calculate efficiency of energy transfer between trophic levels?
NPP/Total energy received originally x 100
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What do food chains show and what do food webs show and what is their difference?
Food chains and food webs show energy transfer between organisms in an ecosystem BUT food chains simple energy transfer lines; food webs are many food chains overlapping in an ecosystem
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Define and explain decomposers and give an example of a type
Such as saprobionts are a part of the food web that breaks down dead/ undigested material therefore the nutrients are recycled
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What do farming practices aim to do?
Increase energy available for human consumption and increasing NPP by reducing pests to reduce energy loss to environment AND reduce respiratory loss
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List the ways to reduce pests to reduce energy lost to the environment+ reduce the biomass loss and increase energy transferred to humans?
1. Simplify food webs 2. Pesticides HOWEVER, a combination of both of these will increase NPP
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Explain how you would use pest control to reduce pests to reduce energy lost to environment?
1. Insecticides+ Herbicides 2. Biological agents such as parasites live/lay eggs on pest and either: kill pests/reduce pest function OR, Pathogens' toxins kill pests.
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Explain why you would simplify a food webs?
Food chains in a food web that take energy which humans could have consumed are rid off, to ensure humans get enough energy from their previous trophic levels so, NPP is increased
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Describe and explain how farmers increase NPP of livestock?
Reduce respiratory loss by 1. keeping animals in pens to reduce movement that uses energy 2. Keep animals indoor= warm= less energy lost by generating body heat
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What is the result of reducing respiratory loss and reducing the energy lost to the environment via pests?
More biomass made= more chemical energy stored= increased NPP= more efficient the energy transfer to HUMANS by making more food in short time at lower cost
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What are the ethical issues of keeping livestock in pens?
Conditions the animals are reared in causes pain, distress and restrict their natural behaviour
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Define natural ecosystems
Ecosystem that has not been changed by humans so, nutrients are recycled via food webs; humans can disrupt the nutrients cycle
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Define sabrobionts
Decomposers (Microorganisms) that recycle chemical elements in dead organisms/ waste products by feed+ break down them
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What is the term to describe how saprobionts digest and describe this digestion
Extracellular digestion= enzymes secreted= digest externally= organic molecules broken down into inorganic ions+ absorb nutrients
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What is the term used to describe saprobionts absorbing the nutrients from dead matter/waste products?
Saprobiont nutrition
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What is the relationship formed by saprobionts and plant roots?
Symbiotic Mycorrhizae Relationship (SMR)
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Discuss and describe the role of micorrhizae fungi in facilitating the water and inorganic ion uptake by plants
Fungi made of long,thin Hyphae strands connect to plant roots+ increase root S.A.= absorb ions from soil + increase H2O uptake THEN, the fungi gets organic compounds like glucose from the plant= SYMBIOTIC(close) MICORRHIZAE RELATIONSHIP
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Crops take minerals from soil as they grow + use it for their tissues; explain what happens when they're harvested?
Crops are removed from the nutrition rich soil and not allowed to die+ decompose there= mineral ions not returned to soil by decomposers in nitrogen + phosphorous cycles
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Discuss and describe what happens to nitrates and phosphates when animals and animal products are removes from the land?
Mineral ions removed too as animals eat grass etc.= take plant nutrients BUT when they're slaughtered somewhere else/ transferred to other fields, nutrients aren't replaced via their remains+ waste
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Discuss and describe what happens to the soil when fertilisers are added?
Replace lost minerals= more energy used for growth= increase energy transfer efficiency
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What are natural and artificial fertilisers?
1. Artificial fertilisers= contain pure inorganic ions and chemicals as powder/pellets 2. Natural fertilisers= contain organic matter like manure/composted veggies/ crop residue/sewage
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Explain why using fertilisers raise environmental issues
More fertilisers than plant needs/ able to use= leaching= eutrophication= algae grow on pond surface= block light to pond plants= no photosynthesis= plants dies+ no O2 released+ bacteria feed on dead matter= further lower O2 conc.= fish die
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Describe and explain which type of fertiliser leads to leaching and which don't
Excess artificial fertiliser has soluble inorganic mineral ions=excess ions not immediately used=leach away from soil after heavy rain. Natural fertilisers contain organic matter with N2 and P2 that are decomposed= their release= controlled= no leach
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Why do crops take in soil minerals?
Build their own tissues as they grow
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Explain what happens to the minerals when plants are harvested
Crops removed from soil they grow on rather than letting them die and decompose there= mineral ions in plants not released back into soil by saprobionts in nitrogen and phosphorous cycles.
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Explain the effects on mineral ions such as phosphate and nitrate ions, when animals are removed from the land
Animals eat the producers= get ions from producers and passed along food chain and they poo+wee= release these ions back to soil but if animals removed to slaughter houses/ transferred to another area= this can't occur
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Explain the effects of fertilisers on nutrients and energy
Added to soil to replace lost nutrients= more energy from ecosystem for growth= more efficient energy transfer
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Other cards in this set

Card 2


What are the sugars from photosynthesis used for?


1.Used in respiration to release energy to grow 2. Make other biological molecules (e.g. cellulose)that make up plant's biomass

Card 3


Define plant biomass and state what happens to the energy stored in an organism


Preview of the front of card 3

Card 4


Describe how energy is transferred through an ecosystem


Preview of the front of card 4

Card 5


State how biomass can be measured


Preview of the front of card 5
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