Energy Transfer And Productivity
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How much of the sun’s radiation is captured by a plant or algae?
1-3%
Why is there energy loss by producers?
• over 90% of the sun’s energy is reflected back into space or absorbed by the atmosphere • not all wavelengths of light can be absorbed and used for photosynthesis • light may not fall on chlorophyll molecule • factors such as low CO2 levels may limit the rate of photosynthesis
Define gross production
• the total quantity of energy that the plants in a given area in a given time • convert to organic matter • is called gross production
Define net production
• some energy is left to be stored in plants, as some energy is used for respiration • the chemical energy store that is left is known as net production
State the equation to work out net production in producers
Net production = gross production - respiratory losses
State the reasons why energy is lost in food chains
• some parts of the organism is not eaten • some parts are not eaten but cannot be digested and are therefore lost in faeces • some of the energy is lost in excretory materials, such as urine • some energy losses occur as heat from respiration and directly from the body to the environment
How does the relative inefficiency of energy between trophic levels affect food chains?
• limits 4/5 organisms because insufficient energy is available to support a large enough breeding population at trophic levels higher than these • total mass of organisms in a particular place (biomass) is less higher at trophic levels • total amount of energy stored is less at each level as one moves up a food chain
How is energy lost from a food chain?
• energy lost to environment through respiration as heat • energy lost to environment during egestion (production of faeces)
How do you calculate net production of consumers?
N = I - (F + R)
What are the ways in which energy loss is reduced from food chains?
• keeping animals indoors keeping them warm - reducing energy transferred to surroundings • predators removed so there is less energy wasted escaping • feeding can be controlled, reduced wastage • restricted movement reduces energy usage in muscle contraction
Give the equation to calculate the efficiency of energy transfer
Energy transfer = (energy available after the transfer / energy available before the transfer) x 100