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gcse science b4 - E

specific for ocr gateway additonal science B.

QuestionAnswer
what do links in food chains and food webs show? different trophic levels
what is passed along the links? energy
what is a pyramid of numbers? when numbers of organisms at different trophic levels are counted
what is a pyramid of biomass? when the mass of organisms at different trophic levels is used
what is a herbivore? an animal that eats plants
what is a carnivore? an animal that eats other animals
what is some of the energy which passes along each link used up in? -growth -waste -heat from respiration
why are the length of food chains limited to a small number of links? because each trophic level loses up to 90% of the available energy
what does the shape of a pyramid of biomass show? energy decreases with increasing trophic levels
what are some uses of biomass? -eaten -fed to other livestock (inefficient transfer of energy) -used as a source of seeds for next year (saves costs) -biofuel
how do you calculate the efficiency of energy transfer? efficiency = energy used for growth (output) / energy supplied (input)
what is the efficiency of energy transfer if there's 3056kj of energy in grass and only 125kj is used for a cow's growth? efficiency = 125 / 3056 = 0.04 or 4%
what can be used as an alternative to fossil fuels? biomass
what can willow trees be used in? burnt in power stations fast growing so there's a always a good supply
what can sugar canes be used for? fermented using yeast to make alcohol
what is alcohol mixed with to make gasohol? petrol
what can gasohol be used for? fuel for cars
what respiration does the process of making alcohol use? anaerobic
first advantage of biofuels renewable - by growing more plants or collecting methane
second advantage of biofuels contribute less to air pollution
third advantage of biofuels countries can be self-reliant for energy
Created by: jirwin
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