Ecosystems Flashcards
What can transfers between trophic levels be measured as?
Energy or biomass (as biomass consists of stored chemical energy)
What is the difference between fresh (wet) and dry biomass?
Wet - living organisms measured - do not need to be killed but presence of water reduces accuracy
Dry - organisms killed and heated to 80°C to remove all water - more accurate estimates of mass, but organisms must be removed from their ecosystem and killed
What is an ecosystem?
All the abiotic and biotic factors in an area and their interactions
Why is some energy not transferred at producer level
Most light energy (90%) cannot be absorbed by plants
Some absorbed energy is used in the reactions of respiration and is not converted to chemical energy in biomass
Net production = gross production - respiratory losses
Why is some energy not transferred at consumer level?
Some parts of organisms (e.g. bones, roots, feathers) are inedible or indigestible. Some energy is lost from the food chain as heat, through movement, or in excrement)
What is the equation for ecological efficiency?
(Energy available after the transfer / energy available before the transfer) x 100
Greenhouses bitch!!!
Pls don’t hurt me :(
How is the efficiency of energy transfer to primary consumers improved?
Restricting movement of farm animals, so that more energy is channeled into growth
Antibiotic use reduces energy expenditure in immune systems
What is decomposition?
Process of large organic molecules (in dead animals and plants) being broken down into smaller inorganic molecules.
Carried out by decomposers (either bacteria or fungi - saprotrophs - feed on dead or waste organic matter)
What is decomposition in the nitrogen cycle called?
Ammonification - breakdown of proteins, nucleic acids and vitamins in dead organisms, faeces and urine to form ammonia (NH3) and ammonium ions (NH4+)
Describe the process of nitrification in the nitrogen cycle
NH3/NH4+ ions to NO2- (nitrite) ions - Nitrosomonas
NO2- to NO3- (nitrate) ions - Nitrobacter
Describe the process of nitrogen fixation in the nitrogen cycle
N2 in the atmosphere converted into NH4+ ions and NH3
Rhizobium - mutualistic (lives in roots of some plants)
Azotobacter - free living in the soil
Describe the process of denitrification in the nitrogen cycle
NO3- to N2 gas Denitrifying bacteria (which require anaerobic conditions)
What is the difference between primary and secondary succession?
Primary succession begins with bare ground that has been newly formed and is lacking soil (e.g. bare volcanic rock)
Secondary succession begins with bare soil that has resulted from deforestation or fire.
What is deflected succession?
Wen human activities prevent a climax community from forming - forms a community known as a plagioclimax
