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Flashcards in 4. Energy Flow Deck (13):

What do all the organisms in a community need?

a supply of energy


Where do plants, algae and some bacteria get their energy from? What are these organisms called? Why?

- light energy and convert it by photosynthesis into chemical energy in carbon compounds
- producers
- because they produce their own food


Where do consumers, detritivores and saprotrophs obtain energy from?

- chemical energy in the carbon compounds in their food

- carbon compounds and the energy contained in them move from organism to organism along food chains, but all food chains start with a producer that originally made the carbon compounds by photosynthesis.
- light is therefore the initial source of energy for the whole community


Draw the diagram explaining energy sources. p56



What does food contain? How is it passed along?

- energy
- by food chains


How does a food chain occur?

when the primary consumer feeds on the producer, and the secondary consumer feeds on the primary consumer, etc.


What happens the further up the food chain you go? Why?

- less food is available and therefore less chemical energy
- due to loss of food and energy between the stages in a food chain


What are the three ways by which food and energy can be passed to detritivores or saprotrophs rather than to the next stage in the food chain?

- some organisms die before they are eaten by the next organism in the chain e.g. foxes do not eat every rabbit; some rabbits die from disease
- some parts of organisms are not eaten e.g. bones, hair, gall bladders
- some parts of organism are indigestible e.g. cellulose in food eaten by humans so is egested in feces


Name another cause of energy loss, that isn't: death; parts not eaten; parts indigestible.

cell respiration - use energy for essential process such as muscle contraction and active transport


What is the energy conversion in cellular respiration?

chemical to heat
- heat is then lost from the organism


Can any organisms convert heat energy back into chemical energy? What happens to it?

- no
- heat is eventually lost from the ecosystem


Organisms cannot convert heat energy back into chemical energy and heat is lost from the ecosystem. What is the significance of this?

ecosystems need an energy source, usually light, to replace energy lost


Summarise energy transfer in an ecosystem with a chart. p56


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