A2 Biology - Energy and Ecosystems
- Created by: dom
- Created on: 05-01-15 13:51
PRODUCERS , DECOMPOSERS AND CONSUMERS
PRODUCERS - PHOTOSYNTHETIC ORGANISMS THAT GET THEIR ENERGY FROM THE SUN
CONSUMERS - OBTAIN ENERGY BY EATING OTHER ORGANISMS
THOSE THAT EAT PRODUCERS - PRIMARY CONSUMERS
THOSE ANIMALS EATING PRIMARY CONSUMERS - SECOINDARY CONSUMERS
THOSE EATING SECONDARY - TERTIARY CONSUMERS
DECOMPOSERS - WHEN PRODUCERS DIE THE ENERGY THEY CONTAIN IS BROKEN DOWN BY DECOMPOSERS
FOOD CHAINS AND WEBS
FOOD CHAINS - FEEDING RELATIONSHIPS IN WHICH THE PRODUCERS ARE EATEN BY PRIMARY ETC ETC.
EACH STAGE IN A CHAIN IS CALLED A TROPHIC LEVEL
ARROWS REPRESENT THE DIRECTION OF ENERGY FLOW
FOOD WEBS - IN REALITY MOST ANIMALS DO NOT RELY ON ONE FOOD SOURCE AND WITHIN A HABITAT MANY FOOD CHAINS LINKED TOGETHER FORM A FOOD WEB
ENERGY TRANSFER BETWEEN TROPHIC LEVELS
SUN IS SOURCE OF ENERGY FOR ECOSYSTEMS - ONLY 1% OF LIGHT ENERGY IS CAPTURED BY PLANTS
PLANTS NORMALLY CONVERT AROUND 1-3% OF SUNS ENERGY AVALIABLE INTO ORGANIC MATTER, MOST OF IT IS NOT CONVERTED BECASEU
- 90% IS REFLECTED BACK INTO SPACE BY CLOUDS AND ATMOSPHERE
- NOT ALL WAVE LENGTHS OF LIGHT CAN BE ABSORBED FOR PHOTOSYNTHSIS
- LIGHT MAY NOT FALL ON CHROROPHYLL
- LIMITING FACTORS CAN LIMIT PHOTOSYNTHESIS
TOTAL QUANTITY OF ENERGY THAT THE PLANTS IN A COMMUNITY CONVERT TO ORGANIC MATTER IS CALLLED - GROSS PRODUCTION
THE AMOUNT OF ENERGY AVALIABLE IN NEXT TROPHIC LEVEL- NET PRODUCTION
NET PRODUCTION = GROSS PRODUCTION - RESPIRATORY LOSSES
WHY IS SOME ENERGY NOT TRANSFERRED
- SOME OF ORGANISM IS NOT EATEN
- SOME PARTS ARE EATEN BUT CANNOT BE DIGESTED AND ARE THEREFORE LOST IN FACES
- SOME ENERGY IS LOST IN EXCRETORY PRODUCTS E.G URINE
- RESPIRATORY LOSSES - IN THE FORM OF HEAT
EFFICENCY OF ENERGY TRANSFER
ENERGY TRANSFER = ENERGY AVALIABLE AFTER THE TRANSFER/ ENERGY AVALIABLE BEFORE TRANSFER X 100
ECOLOGICAL PYRAMIDS
FOOD WEBS AND CHAINS DONT SHOW QUANTATIVE INFORMATION
SOMETIMES USEFUL TO BE KNOW THE NUMBER, MASS OR AMOUNT OF ENERGY STORED BY ORGANISMS AT EACH TROPHIC LEVEL - WE CAN USE ECOLOGICAL PYRAMIDS
PYRAMIDS OF NUMBER
USUALLY NUMBER OF ORGANISMS AT LOWER TROPHIC LEVELS ARE HIGHER THAN THE NUMBER AT HIGHER LEVELS E.G MORE GRASS THAN RABBITS
The population of each organism in a food chain can be shown in a sort of bar chart called apyramid of numbers DRAWBACKS ;
- NO ACCOUNT IS TAKEN OF SIZE - ONE GIANT TREE IS TREATED THE SAME AS A GRASS PEICE - THIS MEANS SOMETIMES THE PYRAMID ISNT A PYRAMID AT ALL - ITS INVERTED
- THE SCALE OF OF INDIVIDUALS CAN BE SO GREAT ITS IMPOSSIBLE TO REPRESENT THEM ACCURATLEY
PYRAMID OF BIOMASS
BIOMASS IS THE TOTAL MASS OF THE PLANTS/ANIMALS IN A PARTICULAR AREA
IT IS A MORE RELIABLE, QUANTATIVE DESCRIPTION OF A FOOD CHAIN.
DRY MASS - A reliable measure of the biomass (as opposed to fresh mass).
The dry matter of a sample or of an object when completely dried (lacks or excluding water).
BECAUSE ORGANISMS MUST BE KILLED TO MEASURE DRY MASS - ONLY SMALL SAMPLE TAKEN - MAY NOT BE REPRESENTATIVE
NEARLY ALWAYS PYRAMID SHAPED
MEASURED IN GRAMS PER CUBIC METRE
PYRAMIDS OF ENERGY
THIS IS THE MOST ACCURATE REPRESENTATION OF ENERGY FLOW
COLLECTING THIS DATA CAN BE DIFFICULT AND COMPLEX
THEY SHOW THE AMOUNT OF ENERGY AVALIABLE IN EACH TROPHIC LEVEL IN KILOJOULES PER SQUARE METRE PER YEAR
ALWAYS PYRAMID SHAPED
AGRICULTURAL ECOSYSTEMS
MADE UP OF DOMESTICATED ANIMALS AND PLANTS USED TO PRODUCE FOOD FOR MANKIND
HUMANS ARE OFTEN AT THE LAST FEW TROPHIC LEVELS OF A FOOD CHAIN MEANING WE ONLY RECIEVE A SMALL PROPORTION OF THE ENERGY AVALAIBLE FROM THE SUN
AGRICULUTURE AIMS TO MAKE AS MUCH ENERGY FROM THE SUN AVALAIBLE AND TRANSFERRED TO HUMANS
DIFFERENCE BEWTEEN NATURAL AND AGRICULTURAL ECOSYS
NATRUAL ECOSYSTEM - SOLAR ENERGY ONLY, LOWER PRODUCTIVITY, MORE SPECIES DIVERSITY, MORE GENETIC DIVERSITY WITHN A SPECIES, NUTRIENTS RECYCLED NATURALLY, POPULATIONS ARE CONTROLLED BY NATRUAL MEANS, SUCH AS COMPETITION AND CLIMATE
AGRICULTURAL ECOSYSTEM - SOLAR ENERGY PLUS ENERGY THROUGH LABOUR AND MACHINES, HIGHER PRODUCTIVITY, LESS SPECIES DIVERSITY, LESS GENETIC DIVERISTY WITHIN A SPECIES NATURAL RECYCLING MORE LIMITED AND SUPPLEMEMTED BY FERTILISERS, CONTROLLED BY NATURAL MEANS AND BY PESTICIDES ETC.
PESTS AND PESTICIDES
PEST - AN ORGANISM THAT COMPETES WITH HUMANS FOR FOOD OR SPACE
PESTICIDE - POSINOUS CHEMICALS THAT KILL PESTS
- HERBICIDE
- FUNGICIDIDES
- INSECTICIDES
AN EFFECTIVE PESTICIDE SHOULD;
- BE SPECIFIC - ONLY TOXIC TO ORGANISM IT IS DIRECTED AT - HARMLESS TO HUMANS
- BIODEGRADE - SO IT BREASK DOWN TO HARMLESS SUBSTANCES IN THE SOIL
- BE COST EFFECTIVE
- NOT ACCUMULATE - SO THAT IT DOES NOT BUILD UP
BIOLOGICAL CONTROLS
INTRODUCING A PREDATOR OF A PEST CAN HELP CONTROL THE INFLUENCE OF PESTS.
ADVANTAGES OF BIOLOGICAL CONTROL OVER USING CHEMICAL PESTICIDES
- VERY SPECIFIC - WHERE AS PESTICIDES ALWAYS HAVE AN EFFECT ON NON TARGET SPECIES
- ONCE INTRODUCED IT CAN REPRODUCE ITSELF - MUST BE REAPPLIED - EXPENSIVE
- PESTS DO NOT BECOME RESISTANT - PESTS DEVELOP GENETIC RESISTANCE TO PESTICIDES
DISADVANTAGES
- DO NOT ACT AS QUICKLY
- CONTROL ORGANISM MAY ITSLEF BECOME A PEST
INTERGRATED PEST CONTROL
INTERGRATED PEST CONTROL AIM TO INTERGRATE ALL FORMS OF PEST CONTROL RATHER THAN BEING RELIANT ON ONE
INTERGRATED CONTROL INVOLVES
- CHOOSING ANIMAL AND PLANT LIFE SUITED TO LOCAL AREA AND RESISTANT TO PESTS
- MANAGEMENT OF HABITAT
- REGULAR MONITORING - FOR SIGNS OF PESTS
- REMOVING PESTS MECHANICALLY IF PESTS EXCEED AN ACCEPABLE POP LEVEL
- USING BIOLOGICAL IF NECESSARY
- USING PESTICIDES AS LAST RESORT
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