IGCSE Biology – 4b: Feeding Relationships
Feeding Types
Producers
o Producers make their own food by photosynthesis, using light energy from the sun.
o They are also known as autotrophs – they produce their own food.
o Producers are plants or algae.
o They are at the start of every food chain.
Consumers
o Consumers eat producers or other consumers, depending on how high in the food
chain they are.
o There are three different types of consumers:
Herbivores – eats only producers
Carnivores – eats only other consumers
Omnivores – eats both consumers and producers
Decomposers
o Decomposers decay dead material and help to recycle nutrients.
o They also feed on the undigested parts of plants and animal matter in faeces.
o An example is bacteria.
Food Chains and Webs
Food Chains
o A food chain is a sequence which shows how each individual feeds on the organism
below it.
o Each arrow shows the flow of energy.
o A typical food chain contains 3-5 organisms.
o Organisms in a food chain are dependent on each other.
o Changes in one part of the food chain can have dramatic effects on the rest of the
chain.
Food Webs
o Food chains can be put together in a food web.
o Food webs show how the food chains are connected.
Energy and Biomass
Trophic Levels
o Trophic levels are the stages of a food chain or web.
o Only 10% of the energy from one trophic level is available to the next trophic level.
Feeding Types
Producers
o Producers make their own food by photosynthesis, using light energy from the sun.
o They are also known as autotrophs – they produce their own food.
o Producers are plants or algae.
o They are at the start of every food chain.
Consumers
o Consumers eat producers or other consumers, depending on how high in the food
chain they are.
o There are three different types of consumers:
Herbivores – eats only producers
Carnivores – eats only other consumers
Omnivores – eats both consumers and producers
Decomposers
o Decomposers decay dead material and help to recycle nutrients.
o They also feed on the undigested parts of plants and animal matter in faeces.
o An example is bacteria.
Food Chains and Webs
Food Chains
o A food chain is a sequence which shows how each individual feeds on the organism
below it.
o Each arrow shows the flow of energy.
o A typical food chain contains 3-5 organisms.
o Organisms in a food chain are dependent on each other.
o Changes in one part of the food chain can have dramatic effects on the rest of the
chain.
Food Webs
o Food chains can be put together in a food web.
o Food webs show how the food chains are connected.
Energy and Biomass
Trophic Levels
o Trophic levels are the stages of a food chain or web.
o Only 10% of the energy from one trophic level is available to the next trophic level.
