Energy flow through the ecosystem Flashcards
Topic-7
what is the energy source for all ecosystems and why?
-the sun
-light for photosynthesis
what % of light energy is not available to plants?
-99.9%
what are the 5 reasons why majority of light energy is not utilised by plants?
-it is reflected due to the waxy cuticle
-some energy is used for evaporation of water
-it misses the chloroplasts
-most of light is in the wrong wavelength
-photosynthetic reactions are insufficient as much of the energy is lost as heat
what % of light energy which reaches the leaf will be converted into chemical energy?
-0.5-1%
what is the GPP? what does it stand for and mean?
-the gross primary production
-the energy compound produced in the plant due to photosynthesis
in what process do plants use up to 50% of their GPP?
-respiration
what is the NGPP?
-the net gross primary production which is the amount of energy compounds which are used for growth
what is the least efficient stage of energy transfer and why? what is the percentage of the total energy which is transferred ?
-the initial transfer between producers and primary consumers
-this is because much of the plant material cannot be accessed e.g. plant roots are not eaten
-most plant material is also very hard to digest due to the presence of cellulose and lignin
-between 5 and 10%
why do excretory losses contribute to energy losses?
-this energy is not available to be transferred to the nest trophic level
what process is the majority of the energy used in that is eaten by primary consumers? how is energy lost through this process?
-respiration
-heat is produced as a by product of respiration which causes energy losses
what type of organisms are respiratory losses high in and why?
-birds and mammals
-this is due to the requirement of a constant body temperature which causes high metabolic activity and therefore high respiration
why is energy transfer between animals more effective/ what percent of the total energy is transferred between primary, secondary and tertiary consumers?
-this is because more of the animal can be eaten and digested
-between 10-20%
why is only a small amount of the total energy transferred to animals, used to make organic compounds, how is the energy lost?
-energy is lost through excretion, uneaten structures e.g. bones, or being used up in respiration where heat is produced as a waste product, or through entry to the decomposer chain
what is the decomposer food chain?
-a food chain which starts with dead organic matter e.g. fallen leaves
-which are eaten and digested by bacteria and fungi
what are the 2 key aims of agricultural ecosystems?
-to increase efficiency of energy transfer into crops
-and to reduce energy losses through unwanted consumption by consumers
how can the productivity of energy production in plants be increased? how is this done naturally and artificially?
-through reducing or eliminating the limiting factor
-this can be naturally or artificially
-naturally through reducing pests through the use of fertilizers
-artificially through greenhouses which increase light, heat and carbon dioxide concentrations
how is productivity of plants increased through appropriate spacing of crops?
-sowing seeds at optimum density levels ensures that competition is reduced whilst allowing maximum coverage of the land used
what is the advantage to humans in increasing plant productivity?
-more energy is available to be transferred through consumers and to humans
what is intensive farming? why is it used to increase animal productivity? what are 2 other advantages?
-intensive farming involves the confinement of animals in small areas
-means less energy is used in movement
-this means less land is utilised by the animals so more room for crops, and manure can be spread more easily?
in intensive farming why are the animals kept in warm temperatures?
-reduces the amount of energy required to maintain body temperature
what are the ethical issues associated with intensive farming? (6 issues)
-animals are under high stress
-and often suffer bone and joint damage
-disease is more likely to spread rapidly due to the confined space
-the over use of antibiotics to prevent disease has also lead to resistance
-reduced genetic diversity due to selective breeding of the most profitable animals
-increased pollution due to increase fossil fuels to maintain temperature of the facilities
is animal or plant transfer of energy to humans more effective and why?
-plants
-humans have the enzymes to digest the cellulose
-also the inefficiency of the transfer of energy through the chain results in the reduction of energy through animal products
what does secondary production mean? how can this be worked out?
-the energy used in the production of new tissue in animals
-using energy budgets
what is the equation for working out the net secondary productivity? what do each of the letters represent?
- P= C-(R+U+F)
-p= net secondary productivity
-c= energy consumed
-r= energy lost in respiration
-u= urine
-f= faeces
